Actual source code: snes.c

petsc-3.14.2 2020-12-03
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  1: #include <petsc/private/snesimpl.h>
  2: #include <petscdmshell.h>
  3: #include <petscdraw.h>
  4: #include <petscds.h>
  5: #include <petscdmadaptor.h>
  6: #include <petscconvest.h>

  8: PetscBool         SNESRegisterAllCalled = PETSC_FALSE;
  9: PetscFunctionList SNESList              = NULL;

 11: /* Logging support */
 12: PetscClassId  SNES_CLASSID, DMSNES_CLASSID;
 13: PetscLogEvent SNES_Solve, SNES_Setup, SNES_FunctionEval, SNES_JacobianEval, SNES_NGSEval, SNES_NGSFuncEval, SNES_NPCSolve, SNES_ObjectiveEval;

 15: /*@
 16:    SNESSetErrorIfNotConverged - Causes SNESSolve() to generate an error if the solver has not converged.

 18:    Logically Collective on SNES

 20:    Input Parameters:
 21: +  snes - iterative context obtained from SNESCreate()
 22: -  flg - PETSC_TRUE indicates you want the error generated

 24:    Options database keys:
 25: .  -snes_error_if_not_converged : this takes an optional truth value (0/1/no/yes/true/false)

 27:    Level: intermediate

 29:    Notes:
 30:     Normally PETSc continues if a linear solver fails to converge, you can call SNESGetConvergedReason() after a SNESSolve()
 31:     to determine if it has converged.

 33: .seealso: SNESGetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
 34: @*/
 35: PetscErrorCode  SNESSetErrorIfNotConverged(SNES snes,PetscBool flg)
 36: {
 40:   snes->errorifnotconverged = flg;
 41:   return(0);
 42: }

 44: /*@
 45:    SNESGetErrorIfNotConverged - Will SNESSolve() generate an error if the solver does not converge?

 47:    Not Collective

 49:    Input Parameter:
 50: .  snes - iterative context obtained from SNESCreate()

 52:    Output Parameter:
 53: .  flag - PETSC_TRUE if it will generate an error, else PETSC_FALSE

 55:    Level: intermediate

 57: .seealso:  SNESSetErrorIfNotConverged(), KSPGetErrorIfNotConverged(), KSPSetErrorIFNotConverged()
 58: @*/
 59: PetscErrorCode  SNESGetErrorIfNotConverged(SNES snes,PetscBool  *flag)
 60: {
 64:   *flag = snes->errorifnotconverged;
 65:   return(0);
 66: }

 68: /*@
 69:     SNESSetAlwaysComputesFinalResidual - does the SNES always compute the residual at the final solution?

 71:    Logically Collective on SNES

 73:     Input Parameters:
 74: +   snes - the shell SNES
 75: -   flg - is the residual computed?

 77:    Level: advanced

 79: .seealso: SNESGetAlwaysComputesFinalResidual()
 80: @*/
 81: PetscErrorCode  SNESSetAlwaysComputesFinalResidual(SNES snes, PetscBool flg)
 82: {
 85:   snes->alwayscomputesfinalresidual = flg;
 86:   return(0);
 87: }

 89: /*@
 90:     SNESGetAlwaysComputesFinalResidual - does the SNES always compute the residual at the final solution?

 92:    Logically Collective on SNES

 94:     Input Parameter:
 95: .   snes - the shell SNES

 97:     Output Parameter:
 98: .   flg - is the residual computed?

100:    Level: advanced

102: .seealso: SNESSetAlwaysComputesFinalResidual()
103: @*/
104: PetscErrorCode  SNESGetAlwaysComputesFinalResidual(SNES snes, PetscBool *flg)
105: {
108:   *flg = snes->alwayscomputesfinalresidual;
109:   return(0);
110: }

112: /*@
113:    SNESSetFunctionDomainError - tells SNES that the input vector to your SNESFunction is not
114:      in the functions domain. For example, negative pressure.

116:    Logically Collective on SNES

118:    Input Parameters:
119: .  snes - the SNES context

121:    Level: advanced

123: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction
124: @*/
125: PetscErrorCode  SNESSetFunctionDomainError(SNES snes)
126: {
129:   if (snes->errorifnotconverged) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"User code indicates input vector is not in the function domain");
130:   snes->domainerror = PETSC_TRUE;
131:   return(0);
132: }

134: /*@
135:    SNESSetJacobianDomainError - tells SNES that computeJacobian does not make sense any more. For example there is a negative element transformation.

137:    Logically Collective on SNES

139:    Input Parameters:
140: .  snes - the SNES context

142:    Level: advanced

144: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction(), SNESSetFunctionDomainError()
145: @*/
146: PetscErrorCode SNESSetJacobianDomainError(SNES snes)
147: {
150:   if (snes->errorifnotconverged) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"User code indicates computeJacobian does not make sense");
151:   snes->jacobiandomainerror = PETSC_TRUE;
152:   return(0);
153: }

155: /*@
156:    SNESSetCheckJacobianDomainError - if or not to check jacobian domain error after each Jacobian evaluation. By default, we check Jacobian domain error
157:    in the debug mode, and do not check it in the optimized mode.

159:    Logically Collective on SNES

161:    Input Parameters:
162: +  snes - the SNES context
163: -  flg  - indicates if or not to check jacobian domain error after each Jacobian evaluation

165:    Level: advanced

167: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction(), SNESSetFunctionDomainError(), SNESGetCheckJacobianDomainError()
168: @*/
169: PetscErrorCode SNESSetCheckJacobianDomainError(SNES snes, PetscBool flg)
170: {
173:   snes->checkjacdomainerror = flg;
174:   return(0);
175: }

177: /*@
178:    SNESGetCheckJacobianDomainError - Get an indicator whether or not we are checking Jacobian domain errors after each Jacobian evaluation.

180:    Logically Collective on SNES

182:    Input Parameters:
183: .  snes - the SNES context

185:    Output Parameters:
186: .  flg  - PETSC_FALSE indicates that we don't check jacobian domain errors after each Jacobian evaluation

188:    Level: advanced

190: .seealso: SNESCreate(), SNESSetFunction(), SNESFunction(), SNESSetFunctionDomainError(), SNESSetCheckJacobianDomainError()
191: @*/
192: PetscErrorCode SNESGetCheckJacobianDomainError(SNES snes, PetscBool *flg)
193: {
197:   *flg = snes->checkjacdomainerror;
198:   return(0);
199: }

201: /*@
202:    SNESGetFunctionDomainError - Gets the status of the domain error after a call to SNESComputeFunction;

204:    Logically Collective on SNES

206:    Input Parameters:
207: .  snes - the SNES context

209:    Output Parameters:
210: .  domainerror - Set to PETSC_TRUE if there's a domain error; PETSC_FALSE otherwise.

212:    Level: advanced

214: .seealso: SNESSetFunctionDomainError(), SNESComputeFunction()
215: @*/
216: PetscErrorCode  SNESGetFunctionDomainError(SNES snes, PetscBool *domainerror)
217: {
221:   *domainerror = snes->domainerror;
222:   return(0);
223: }

225: /*@
226:    SNESGetJacobianDomainError - Gets the status of the Jacobian domain error after a call to SNESComputeJacobian;

228:    Logically Collective on SNES

230:    Input Parameters:
231: .  snes - the SNES context

233:    Output Parameters:
234: .  domainerror - Set to PETSC_TRUE if there's a jacobian domain error; PETSC_FALSE otherwise.

236:    Level: advanced

238: .seealso: SNESSetFunctionDomainError(), SNESComputeFunction(),SNESGetFunctionDomainError()
239: @*/
240: PetscErrorCode SNESGetJacobianDomainError(SNES snes, PetscBool *domainerror)
241: {
245:   *domainerror = snes->jacobiandomainerror;
246:   return(0);
247: }

249: /*@C
250:   SNESLoad - Loads a SNES that has been stored in binary  with SNESView().

252:   Collective on PetscViewer

254:   Input Parameters:
255: + newdm - the newly loaded SNES, this needs to have been created with SNESCreate() or
256:            some related function before a call to SNESLoad().
257: - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()

259:    Level: intermediate

261:   Notes:
262:    The type is determined by the data in the file, any type set into the SNES before this call is ignored.

264:   Notes for advanced users:
265:   Most users should not need to know the details of the binary storage
266:   format, since SNESLoad() and TSView() completely hide these details.
267:   But for anyone who's interested, the standard binary matrix storage
268:   format is
269: .vb
270:      has not yet been determined
271: .ve

273: .seealso: PetscViewerBinaryOpen(), SNESView(), MatLoad(), VecLoad()
274: @*/
275: PetscErrorCode  SNESLoad(SNES snes, PetscViewer viewer)
276: {
278:   PetscBool      isbinary;
279:   PetscInt       classid;
280:   char           type[256];
281:   KSP            ksp;
282:   DM             dm;
283:   DMSNES         dmsnes;

288:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
289:   if (!isbinary) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Invalid viewer; open viewer with PetscViewerBinaryOpen()");

291:   PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);
292:   if (classid != SNES_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_WRONG,"Not SNES next in file");
293:   PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);
294:   SNESSetType(snes, type);
295:   if (snes->ops->load) {
296:     (*snes->ops->load)(snes,viewer);
297:   }
298:   SNESGetDM(snes,&dm);
299:   DMGetDMSNES(dm,&dmsnes);
300:   DMSNESLoad(dmsnes,viewer);
301:   SNESGetKSP(snes,&ksp);
302:   KSPLoad(ksp,viewer);
303:   return(0);
304: }

306: #include <petscdraw.h>
307: #if defined(PETSC_HAVE_SAWS)
308: #include <petscviewersaws.h>
309: #endif

311: /*@C
312:    SNESViewFromOptions - View from Options

314:    Collective on SNES

316:    Input Parameters:
317: +  A - the application ordering context
318: .  obj - Optional object
319: -  name - command line option

321:    Level: intermediate
322: .seealso:  SNES, SNESView, PetscObjectViewFromOptions(), SNESCreate()
323: @*/
324: PetscErrorCode  SNESViewFromOptions(SNES A,PetscObject obj,const char name[])
325: {

330:   PetscObjectViewFromOptions((PetscObject)A,obj,name);
331:   return(0);
332: }

334: PETSC_EXTERN PetscErrorCode SNESComputeJacobian_DMDA(SNES,Vec,Mat,Mat,void*);

336: /*@C
337:    SNESView - Prints the SNES data structure.

339:    Collective on SNES

341:    Input Parameters:
342: +  SNES - the SNES context
343: -  viewer - visualization context

345:    Options Database Key:
346: .  -snes_view - Calls SNESView() at end of SNESSolve()

348:    Notes:
349:    The available visualization contexts include
350: +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
351: -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
352:          output where only the first processor opens
353:          the file.  All other processors send their
354:          data to the first processor to print.

356:    The user can open an alternative visualization context with
357:    PetscViewerASCIIOpen() - output to a specified file.

359:    Level: beginner

361: .seealso: PetscViewerASCIIOpen()
362: @*/
363: PetscErrorCode  SNESView(SNES snes,PetscViewer viewer)
364: {
365:   SNESKSPEW      *kctx;
367:   KSP            ksp;
368:   SNESLineSearch linesearch;
369:   PetscBool      iascii,isstring,isbinary,isdraw;
370:   DMSNES         dmsnes;
371: #if defined(PETSC_HAVE_SAWS)
372:   PetscBool      issaws;
373: #endif

377:   if (!viewer) {
378:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&viewer);
379:   }

383:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
384:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);
385:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
386:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
387: #if defined(PETSC_HAVE_SAWS)
388:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&issaws);
389: #endif
390:   if (iascii) {
391:     SNESNormSchedule normschedule;
392:     DM               dm;
393:     PetscErrorCode   (*cJ)(SNES,Vec,Mat,Mat,void*);
394:     void             *ctx;
395:     const char       *pre = "";

397:     PetscObjectPrintClassNamePrefixType((PetscObject)snes,viewer);
398:     if (!snes->setupcalled) {
399:       PetscViewerASCIIPrintf(viewer,"  SNES has not been set up so information may be incomplete\n");
400:     }
401:     if (snes->ops->view) {
402:       PetscViewerASCIIPushTab(viewer);
403:       (*snes->ops->view)(snes,viewer);
404:       PetscViewerASCIIPopTab(viewer);
405:     }
406:     PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, maximum function evaluations=%D\n",snes->max_its,snes->max_funcs);
407:     PetscViewerASCIIPrintf(viewer,"  tolerances: relative=%g, absolute=%g, solution=%g\n",(double)snes->rtol,(double)snes->abstol,(double)snes->stol);
408:     if (snes->usesksp) {
409:       PetscViewerASCIIPrintf(viewer,"  total number of linear solver iterations=%D\n",snes->linear_its);
410:     }
411:     PetscViewerASCIIPrintf(viewer,"  total number of function evaluations=%D\n",snes->nfuncs);
412:     SNESGetNormSchedule(snes, &normschedule);
413:     if (normschedule > 0) {PetscViewerASCIIPrintf(viewer,"  norm schedule %s\n",SNESNormSchedules[normschedule]);}
414:     if (snes->gridsequence) {
415:       PetscViewerASCIIPrintf(viewer,"  total number of grid sequence refinements=%D\n",snes->gridsequence);
416:     }
417:     if (snes->ksp_ewconv) {
418:       kctx = (SNESKSPEW*)snes->kspconvctx;
419:       if (kctx) {
420:         PetscViewerASCIIPrintf(viewer,"  Eisenstat-Walker computation of KSP relative tolerance (version %D)\n",kctx->version);
421:         PetscViewerASCIIPrintf(viewer,"    rtol_0=%g, rtol_max=%g, threshold=%g\n",(double)kctx->rtol_0,(double)kctx->rtol_max,(double)kctx->threshold);
422:         PetscViewerASCIIPrintf(viewer,"    gamma=%g, alpha=%g, alpha2=%g\n",(double)kctx->gamma,(double)kctx->alpha,(double)kctx->alpha2);
423:       }
424:     }
425:     if (snes->lagpreconditioner == -1) {
426:       PetscViewerASCIIPrintf(viewer,"  Preconditioned is never rebuilt\n");
427:     } else if (snes->lagpreconditioner > 1) {
428:       PetscViewerASCIIPrintf(viewer,"  Preconditioned is rebuilt every %D new Jacobians\n",snes->lagpreconditioner);
429:     }
430:     if (snes->lagjacobian == -1) {
431:       PetscViewerASCIIPrintf(viewer,"  Jacobian is never rebuilt\n");
432:     } else if (snes->lagjacobian > 1) {
433:       PetscViewerASCIIPrintf(viewer,"  Jacobian is rebuilt every %D SNES iterations\n",snes->lagjacobian);
434:     }
435:     SNESGetDM(snes,&dm);
436:     DMSNESGetJacobian(dm,&cJ,&ctx);
437:     if (snes->mf_operator) {
438:       PetscViewerASCIIPrintf(viewer,"  Jacobian is applied matrix-free with differencing\n");
439:       pre  = "Preconditioning ";
440:     }
441:     if (cJ == SNESComputeJacobianDefault) {
442:       PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using finite differences one column at a time\n",pre);
443:     } else if (cJ == SNESComputeJacobianDefaultColor) {
444:       PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using finite differences with coloring\n",pre);
445:     /* it slightly breaks data encapsulation for access the DMDA information directly */
446:     } else if (cJ == SNESComputeJacobian_DMDA) {
447:       MatFDColoring fdcoloring;
448:       PetscObjectQuery((PetscObject)dm,"DMDASNES_FDCOLORING",(PetscObject*)&fdcoloring);
449:       if (fdcoloring) {
450:         PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using colored finite differences on a DMDA\n",pre);
451:       } else {
452:         PetscViewerASCIIPrintf(viewer,"  %sJacobian is built using a DMDA local Jacobian\n",pre);
453:       }
454:     } else if (snes->mf) {
455:       PetscViewerASCIIPrintf(viewer,"  Jacobian is applied matrix-free with differencing, no explict Jacobian\n");
456:     }
457:   } else if (isstring) {
458:     const char *type;
459:     SNESGetType(snes,&type);
460:     PetscViewerStringSPrintf(viewer," SNESType: %-7.7s",type);
461:     if (snes->ops->view) {(*snes->ops->view)(snes,viewer);}
462:   } else if (isbinary) {
463:     PetscInt    classid = SNES_FILE_CLASSID;
464:     MPI_Comm    comm;
465:     PetscMPIInt rank;
466:     char        type[256];

468:     PetscObjectGetComm((PetscObject)snes,&comm);
469:     MPI_Comm_rank(comm,&rank);
470:     if (!rank) {
471:       PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT);
472:       PetscStrncpy(type,((PetscObject)snes)->type_name,sizeof(type));
473:       PetscViewerBinaryWrite(viewer,type,sizeof(type),PETSC_CHAR);
474:     }
475:     if (snes->ops->view) {
476:       (*snes->ops->view)(snes,viewer);
477:     }
478:   } else if (isdraw) {
479:     PetscDraw draw;
480:     char      str[36];
481:     PetscReal x,y,bottom,h;

483:     PetscViewerDrawGetDraw(viewer,0,&draw);
484:     PetscDrawGetCurrentPoint(draw,&x,&y);
485:     PetscStrncpy(str,"SNES: ",sizeof(str));
486:     PetscStrlcat(str,((PetscObject)snes)->type_name,sizeof(str));
487:     PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_BLUE,PETSC_DRAW_BLACK,str,NULL,&h);
488:     bottom = y - h;
489:     PetscDrawPushCurrentPoint(draw,x,bottom);
490:     if (snes->ops->view) {
491:       (*snes->ops->view)(snes,viewer);
492:     }
493: #if defined(PETSC_HAVE_SAWS)
494:   } else if (issaws) {
495:     PetscMPIInt rank;
496:     const char *name;

498:     PetscObjectGetName((PetscObject)snes,&name);
499:     MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
500:     if (!((PetscObject)snes)->amsmem && !rank) {
501:       char       dir[1024];

503:       PetscObjectViewSAWs((PetscObject)snes,viewer);
504:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);
505:       PetscStackCallSAWs(SAWs_Register,(dir,&snes->iter,1,SAWs_READ,SAWs_INT));
506:       if (!snes->conv_hist) {
507:         SNESSetConvergenceHistory(snes,NULL,NULL,PETSC_DECIDE,PETSC_TRUE);
508:       }
509:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/conv_hist",name);
510:       PetscStackCallSAWs(SAWs_Register,(dir,snes->conv_hist,10,SAWs_READ,SAWs_DOUBLE));
511:     }
512: #endif
513:   }
514:   if (snes->linesearch) {
515:     SNESGetLineSearch(snes, &linesearch);
516:     PetscViewerASCIIPushTab(viewer);
517:     SNESLineSearchView(linesearch, viewer);
518:     PetscViewerASCIIPopTab(viewer);
519:   }
520:   if (snes->npc && snes->usesnpc) {
521:     PetscViewerASCIIPushTab(viewer);
522:     SNESView(snes->npc, viewer);
523:     PetscViewerASCIIPopTab(viewer);
524:   }
525:   PetscViewerASCIIPushTab(viewer);
526:   DMGetDMSNES(snes->dm,&dmsnes);
527:   DMSNESView(dmsnes, viewer);
528:   PetscViewerASCIIPopTab(viewer);
529:   if (snes->usesksp) {
530:     SNESGetKSP(snes,&ksp);
531:     PetscViewerASCIIPushTab(viewer);
532:     KSPView(ksp,viewer);
533:     PetscViewerASCIIPopTab(viewer);
534:   }
535:   if (isdraw) {
536:     PetscDraw draw;
537:     PetscViewerDrawGetDraw(viewer,0,&draw);
538:     PetscDrawPopCurrentPoint(draw);
539:   }
540:   return(0);
541: }

543: /*
544:   We retain a list of functions that also take SNES command
545:   line options. These are called at the end SNESSetFromOptions()
546: */
547: #define MAXSETFROMOPTIONS 5
548: static PetscInt numberofsetfromoptions;
549: static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);

551: /*@C
552:   SNESAddOptionsChecker - Adds an additional function to check for SNES options.

554:   Not Collective

556:   Input Parameter:
557: . snescheck - function that checks for options

559:   Level: developer

561: .seealso: SNESSetFromOptions()
562: @*/
563: PetscErrorCode  SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
564: {
566:   if (numberofsetfromoptions >= MAXSETFROMOPTIONS) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %D allowed", MAXSETFROMOPTIONS);
567:   othersetfromoptions[numberofsetfromoptions++] = snescheck;
568:   return(0);
569: }

571: PETSC_INTERN PetscErrorCode SNESDefaultMatrixFreeCreate2(SNES,Vec,Mat*);

573: static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
574: {
575:   Mat            J;
577:   MatNullSpace   nullsp;


582:   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
583:     Mat A = snes->jacobian, B = snes->jacobian_pre;
584:     MatCreateVecs(A ? A : B, NULL,&snes->vec_func);
585:   }

587:   if (version == 1) {
588:     MatCreateSNESMF(snes,&J);
589:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
590:     MatSetFromOptions(J);
591:   } else if (version == 2) {
592:     if (!snes->vec_func) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"SNESSetFunction() must be called first");
593: #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128) && !defined(PETSC_USE_REAL___FP16)
594:     SNESDefaultMatrixFreeCreate2(snes,snes->vec_func,&J);
595: #else
596:     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP, "matrix-free operator routines (version 2)");
597: #endif
598:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator routines, only version 1 and 2");

600:   /* attach any user provided null space that was on Amat to the newly created matrix free matrix */
601:   if (snes->jacobian) {
602:     MatGetNullSpace(snes->jacobian,&nullsp);
603:     if (nullsp) {
604:       MatSetNullSpace(J,nullsp);
605:     }
606:   }

608:   PetscInfo1(snes,"Setting default matrix-free operator routines (version %D)\n", version);
609:   if (hasOperator) {

611:     /* This version replaces the user provided Jacobian matrix with a
612:        matrix-free version but still employs the user-provided preconditioner matrix. */
613:     SNESSetJacobian(snes,J,NULL,NULL,NULL);
614:   } else {
615:     /* This version replaces both the user-provided Jacobian and the user-
616:      provided preconditioner Jacobian with the default matrix free version. */
617:     if ((snes->npcside== PC_LEFT) && snes->npc) {
618:       if (!snes->jacobian){SNESSetJacobian(snes,J,NULL,NULL,NULL);}
619:     } else {
620:       KSP       ksp;
621:       PC        pc;
622:       PetscBool match;

624:       SNESSetJacobian(snes,J,J,MatMFFDComputeJacobian,NULL);
625:       /* Force no preconditioner */
626:       SNESGetKSP(snes,&ksp);
627:       KSPGetPC(ksp,&pc);
628:       PetscObjectTypeCompare((PetscObject)pc,PCSHELL,&match);
629:       if (!match) {
630:         PetscInfo(snes,"Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n");
631:         PCSetType(pc,PCNONE);
632:       }
633:     }
634:   }
635:   MatDestroy(&J);
636:   return(0);
637: }

639: static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine,Mat Restrict,Vec Rscale,Mat Inject,DM dmcoarse,void *ctx)
640: {
641:   SNES           snes = (SNES)ctx;
643:   Vec            Xfine,Xfine_named = NULL,Xcoarse;

646:   if (PetscLogPrintInfo) {
647:     PetscInt finelevel,coarselevel,fineclevel,coarseclevel;
648:     DMGetRefineLevel(dmfine,&finelevel);
649:     DMGetCoarsenLevel(dmfine,&fineclevel);
650:     DMGetRefineLevel(dmcoarse,&coarselevel);
651:     DMGetCoarsenLevel(dmcoarse,&coarseclevel);
652:     PetscInfo4(dmfine,"Restricting SNES solution vector from level %D-%D to level %D-%D\n",finelevel,fineclevel,coarselevel,coarseclevel);
653:   }
654:   if (dmfine == snes->dm) Xfine = snes->vec_sol;
655:   else {
656:     DMGetNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);
657:     Xfine = Xfine_named;
658:   }
659:   DMGetNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);
660:   if (Inject) {
661:     MatRestrict(Inject,Xfine,Xcoarse);
662:   } else {
663:     MatRestrict(Restrict,Xfine,Xcoarse);
664:     VecPointwiseMult(Xcoarse,Xcoarse,Rscale);
665:   }
666:   DMRestoreNamedGlobalVector(dmcoarse,"SNESVecSol",&Xcoarse);
667:   if (Xfine_named) {DMRestoreNamedGlobalVector(dmfine,"SNESVecSol",&Xfine_named);}
668:   return(0);
669: }

671: static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm,DM dmc,void *ctx)
672: {

676:   DMCoarsenHookAdd(dmc,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,ctx);
677:   return(0);
678: }

680: /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
681:  * safely call SNESGetDM() in their residual evaluation routine. */
682: static PetscErrorCode KSPComputeOperators_SNES(KSP ksp,Mat A,Mat B,void *ctx)
683: {
684:   SNES           snes = (SNES)ctx;
686:   Vec            X,Xnamed = NULL;
687:   DM             dmsave;
688:   void           *ctxsave;
689:   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*) = NULL;

692:   dmsave = snes->dm;
693:   KSPGetDM(ksp,&snes->dm);
694:   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
695:   else {                                     /* We are on a coarser level, this vec was initialized using a DM restrict hook */
696:     DMGetNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);
697:     X    = Xnamed;
698:     SNESGetJacobian(snes,NULL,NULL,&jac,&ctxsave);
699:     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
700:     if (jac == SNESComputeJacobianDefaultColor) {
701:       SNESSetJacobian(snes,NULL,NULL,SNESComputeJacobianDefaultColor,NULL);
702:     }
703:   }
704:   /* Make sure KSP DM has the Jacobian computation routine */
705:   {
706:     DMSNES sdm;

708:     DMGetDMSNES(snes->dm, &sdm);
709:     if (!sdm->ops->computejacobian) {
710:       DMCopyDMSNES(dmsave, snes->dm);
711:     }
712:   }
713:   /* Compute the operators */
714:   SNESComputeJacobian(snes,X,A,B);
715:   /* Put the previous context back */
716:   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) {
717:     SNESSetJacobian(snes,NULL,NULL,jac,ctxsave);
718:   }

720:   if (Xnamed) {DMRestoreNamedGlobalVector(snes->dm,"SNESVecSol",&Xnamed);}
721:   snes->dm = dmsave;
722:   return(0);
723: }

725: /*@
726:    SNESSetUpMatrices - ensures that matrices are available for SNES, to be called by SNESSetUp_XXX()

728:    Collective

730:    Input Arguments:
731: .  snes - snes to configure

733:    Level: developer

735: .seealso: SNESSetUp()
736: @*/
737: PetscErrorCode SNESSetUpMatrices(SNES snes)
738: {
740:   DM             dm;
741:   DMSNES         sdm;

744:   SNESGetDM(snes,&dm);
745:   DMGetDMSNES(dm,&sdm);
746:   if (!snes->jacobian && snes->mf) {
747:     Mat  J;
748:     void *functx;
749:     MatCreateSNESMF(snes,&J);
750:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
751:     MatSetFromOptions(J);
752:     SNESGetFunction(snes,NULL,NULL,&functx);
753:     SNESSetJacobian(snes,J,J,NULL,NULL);
754:     MatDestroy(&J);
755:   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
756:     Mat J,B;
757:     MatCreateSNESMF(snes,&J);
758:     MatMFFDSetOptionsPrefix(J,((PetscObject)snes)->prefix);
759:     MatSetFromOptions(J);
760:     DMCreateMatrix(snes->dm,&B);
761:     /* sdm->computejacobian was already set to reach here */
762:     SNESSetJacobian(snes,J,B,NULL,NULL);
763:     MatDestroy(&J);
764:     MatDestroy(&B);
765:   } else if (!snes->jacobian_pre) {
766:     PetscErrorCode (*nspconstr)(DM, PetscInt, PetscInt, MatNullSpace *);
767:     PetscDS          prob;
768:     Mat              J, B;
769:     MatNullSpace     nullspace = NULL;
770:     PetscBool        hasPrec   = PETSC_FALSE;
771:     PetscInt         Nf;

773:     J    = snes->jacobian;
774:     DMGetDS(dm, &prob);
775:     if (prob) {PetscDSHasJacobianPreconditioner(prob, &hasPrec);}
776:     if (J)            {PetscObjectReference((PetscObject) J);}
777:     else if (hasPrec) {DMCreateMatrix(snes->dm, &J);}
778:     DMCreateMatrix(snes->dm, &B);
779:     PetscDSGetNumFields(prob, &Nf);
780:     DMGetNullSpaceConstructor(snes->dm, Nf, &nspconstr);
781:     if (nspconstr) (*nspconstr)(snes->dm, Nf, Nf, &nullspace);
782:     MatSetNullSpace(B, nullspace);
783:     MatNullSpaceDestroy(&nullspace);
784:     SNESSetJacobian(snes, J ? J : B, B, NULL, NULL);
785:     MatDestroy(&J);
786:     MatDestroy(&B);
787:   }
788:   {
789:     KSP ksp;
790:     SNESGetKSP(snes,&ksp);
791:     KSPSetComputeOperators(ksp,KSPComputeOperators_SNES,snes);
792:     DMCoarsenHookAdd(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);
793:   }
794:   return(0);
795: }

797: /*@C
798:    SNESMonitorSetFromOptions - Sets a monitor function and viewer appropriate for the type indicated by the user

800:    Collective on SNES

802:    Input Parameters:
803: +  snes - SNES object you wish to monitor
804: .  name - the monitor type one is seeking
805: .  help - message indicating what monitoring is done
806: .  manual - manual page for the monitor
807: .  monitor - the monitor function
808: -  monitorsetup - a function that is called once ONLY if the user selected this monitor that may set additional features of the SNES or PetscViewer objects

810:    Level: developer

812: .seealso: PetscOptionsGetViewer(), PetscOptionsGetReal(), PetscOptionsHasName(), PetscOptionsGetString(),
813:           PetscOptionsGetIntArray(), PetscOptionsGetRealArray(), PetscOptionsBool()
814:           PetscOptionsInt(), PetscOptionsString(), PetscOptionsReal(), PetscOptionsBool(),
815:           PetscOptionsName(), PetscOptionsBegin(), PetscOptionsEnd(), PetscOptionsHead(),
816:           PetscOptionsStringArray(),PetscOptionsRealArray(), PetscOptionsScalar(),
817:           PetscOptionsBoolGroupBegin(), PetscOptionsBoolGroup(), PetscOptionsBoolGroupEnd(),
818:           PetscOptionsFList(), PetscOptionsEList()
819: @*/
820: PetscErrorCode  SNESMonitorSetFromOptions(SNES snes,const char name[],const char help[], const char manual[],PetscErrorCode (*monitor)(SNES,PetscInt,PetscReal,PetscViewerAndFormat*),PetscErrorCode (*monitorsetup)(SNES,PetscViewerAndFormat*))
821: {
822:   PetscErrorCode    ierr;
823:   PetscViewer       viewer;
824:   PetscViewerFormat format;
825:   PetscBool         flg;

828:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,name,&viewer,&format,&flg);
829:   if (flg) {
830:     PetscViewerAndFormat *vf;
831:     PetscViewerAndFormatCreate(viewer,format,&vf);
832:     PetscObjectDereference((PetscObject)viewer);
833:     if (monitorsetup) {
834:       (*monitorsetup)(snes,vf);
835:     }
836:     SNESMonitorSet(snes,(PetscErrorCode (*)(SNES,PetscInt,PetscReal,void*))monitor,vf,(PetscErrorCode (*)(void**))PetscViewerAndFormatDestroy);
837:   }
838:   return(0);
839: }

841: /*@
842:    SNESSetFromOptions - Sets various SNES and KSP parameters from user options.

844:    Collective on SNES

846:    Input Parameter:
847: .  snes - the SNES context

849:    Options Database Keys:
850: +  -snes_type <type> - newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas, SNESType for complete list
851: .  -snes_stol - convergence tolerance in terms of the norm
852:                 of the change in the solution between steps
853: .  -snes_atol <abstol> - absolute tolerance of residual norm
854: .  -snes_rtol <rtol> - relative decrease in tolerance norm from initial
855: .  -snes_divergence_tolerance <divtol> - if the residual goes above divtol*rnorm0, exit with divergence
856: .  -snes_force_iteration <force> - force SNESSolve() to take at least one iteration
857: .  -snes_max_it <max_it> - maximum number of iterations
858: .  -snes_max_funcs <max_funcs> - maximum number of function evaluations
859: .  -snes_max_fail <max_fail> - maximum number of line search failures allowed before stopping, default is none
860: .  -snes_max_linear_solve_fail - number of linear solver failures before SNESSolve() stops
861: .  -snes_lag_preconditioner <lag> - how often preconditioner is rebuilt (use -1 to never rebuild)
862: .  -snes_lag_preconditioner_persists <true,false> - retains the -snes_lag_preconditioner information across multiple SNESSolve()
863: .  -snes_lag_jacobian <lag> - how often Jacobian is rebuilt (use -1 to never rebuild)
864: .  -snes_lag_jacobian_persists <true,false> - retains the -snes_lag_jacobian information across multiple SNESSolve()
865: .  -snes_trtol <trtol> - trust region tolerance
866: .  -snes_no_convergence_test - skip convergence test in nonlinear
867:                                solver; hence iterations will continue until max_it
868:                                or some other criterion is reached. Saves expense
869:                                of convergence test
870: .  -snes_monitor [ascii][:filename][:viewer format] - prints residual norm at each iteration. if no filename given prints to stdout
871: .  -snes_monitor_solution [ascii binary draw][:filename][:viewer format] - plots solution at each iteration
872: .  -snes_monitor_residual [ascii binary draw][:filename][:viewer format] - plots residual (not its norm) at each iteration
873: .  -snes_monitor_solution_update [ascii binary draw][:filename][:viewer format] - plots update to solution at each iteration
874: .  -snes_monitor_lg_residualnorm - plots residual norm at each iteration
875: .  -snes_monitor_lg_range - plots residual norm at each iteration
876: .  -snes_fd - use finite differences to compute Jacobian; very slow, only for testing
877: .  -snes_fd_color - use finite differences with coloring to compute Jacobian
878: .  -snes_mf_ksp_monitor - if using matrix-free multiply then print h at each KSP iteration
879: .  -snes_converged_reason - print the reason for convergence/divergence after each solve
880: .  -npc_snes_type <type> - the SNES type to use as a nonlinear preconditioner
881: .   -snes_test_jacobian <optional threshold> - compare the user provided Jacobian with one computed via finite differences to check for errors.  If a threshold is given, display only those entries whose difference is greater than the threshold.
882: -   -snes_test_jacobian_view - display the user provided Jacobian, the finite difference Jacobian and the difference between them to help users detect the location of errors in the user provided Jacobian.

884:     Options Database for Eisenstat-Walker method:
885: +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
886: .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
887: .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
888: .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
889: .  -snes_ksp_ew_gamma <gamma> - Sets gamma
890: .  -snes_ksp_ew_alpha <alpha> - Sets alpha
891: .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
892: -  -snes_ksp_ew_threshold <threshold> - Sets threshold

894:    Notes:
895:    To see all options, run your program with the -help option or consult the users manual

897:    Notes:
898:       SNES supports three approaches for computing (approximate) Jacobians: user provided via SNESSetJacobian(), matrix free, and computing explictly with
899:       finite differences and coloring using MatFDColoring. It is also possible to use automatic differentiation and the MatFDColoring object.

901:    Level: beginner

903: .seealso: SNESSetOptionsPrefix(), SNESResetFromOptions(), SNES, SNESCreate()
904: @*/
905: PetscErrorCode  SNESSetFromOptions(SNES snes)
906: {
907:   PetscBool      flg,pcset,persist,set;
908:   PetscInt       i,indx,lag,grids;
909:   const char     *deft        = SNESNEWTONLS;
910:   const char     *convtests[] = {"default","skip"};
911:   SNESKSPEW      *kctx        = NULL;
912:   char           type[256], monfilename[PETSC_MAX_PATH_LEN];
914:   PCSide         pcside;
915:   const char     *optionsprefix;

919:   SNESRegisterAll();
920:   PetscObjectOptionsBegin((PetscObject)snes);
921:   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
922:   PetscOptionsFList("-snes_type","Nonlinear solver method","SNESSetType",SNESList,deft,type,256,&flg);
923:   if (flg) {
924:     SNESSetType(snes,type);
925:   } else if (!((PetscObject)snes)->type_name) {
926:     SNESSetType(snes,deft);
927:   }
928:   PetscOptionsReal("-snes_stol","Stop if step length less than","SNESSetTolerances",snes->stol,&snes->stol,NULL);
929:   PetscOptionsReal("-snes_atol","Stop if function norm less than","SNESSetTolerances",snes->abstol,&snes->abstol,NULL);

931:   PetscOptionsReal("-snes_rtol","Stop if decrease in function norm less than","SNESSetTolerances",snes->rtol,&snes->rtol,NULL);
932:   PetscOptionsReal("-snes_divergence_tolerance","Stop if residual norm increases by this factor","SNESSetDivergenceTolerance",snes->divtol,&snes->divtol,NULL);
933:   PetscOptionsInt("-snes_max_it","Maximum iterations","SNESSetTolerances",snes->max_its,&snes->max_its,NULL);
934:   PetscOptionsInt("-snes_max_funcs","Maximum function evaluations","SNESSetTolerances",snes->max_funcs,&snes->max_funcs,NULL);
935:   PetscOptionsInt("-snes_max_fail","Maximum nonlinear step failures","SNESSetMaxNonlinearStepFailures",snes->maxFailures,&snes->maxFailures,NULL);
936:   PetscOptionsInt("-snes_max_linear_solve_fail","Maximum failures in linear solves allowed","SNESSetMaxLinearSolveFailures",snes->maxLinearSolveFailures,&snes->maxLinearSolveFailures,NULL);
937:   PetscOptionsBool("-snes_error_if_not_converged","Generate error if solver does not converge","SNESSetErrorIfNotConverged",snes->errorifnotconverged,&snes->errorifnotconverged,NULL);
938:   PetscOptionsBool("-snes_force_iteration","Force SNESSolve() to take at least one iteration","SNESSetForceIteration",snes->forceiteration,&snes->forceiteration,NULL);
939:   PetscOptionsBool("-snes_check_jacobian_domain_error","Check Jacobian domain error after Jacobian evaluation","SNESCheckJacobianDomainError",snes->checkjacdomainerror,&snes->checkjacdomainerror,NULL);

941:   PetscOptionsInt("-snes_lag_preconditioner","How often to rebuild preconditioner","SNESSetLagPreconditioner",snes->lagpreconditioner,&lag,&flg);
942:   if (flg) {
943:     if (lag == -1) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Cannot set the lag to -1 from the command line since the preconditioner must be built as least once, perhaps you mean -2");
944:     SNESSetLagPreconditioner(snes,lag);
945:   }
946:   PetscOptionsBool("-snes_lag_preconditioner_persists","Preconditioner lagging through multiple SNES solves","SNESSetLagPreconditionerPersists",snes->lagjac_persist,&persist,&flg);
947:   if (flg) {
948:     SNESSetLagPreconditionerPersists(snes,persist);
949:   }
950:   PetscOptionsInt("-snes_lag_jacobian","How often to rebuild Jacobian","SNESSetLagJacobian",snes->lagjacobian,&lag,&flg);
951:   if (flg) {
952:     if (lag == -1) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Cannot set the lag to -1 from the command line since the Jacobian must be built as least once, perhaps you mean -2");
953:     SNESSetLagJacobian(snes,lag);
954:   }
955:   PetscOptionsBool("-snes_lag_jacobian_persists","Jacobian lagging through multiple SNES solves","SNESSetLagJacobianPersists",snes->lagjac_persist,&persist,&flg);
956:   if (flg) {
957:     SNESSetLagJacobianPersists(snes,persist);
958:   }

960:   PetscOptionsInt("-snes_grid_sequence","Use grid sequencing to generate initial guess","SNESSetGridSequence",snes->gridsequence,&grids,&flg);
961:   if (flg) {
962:     SNESSetGridSequence(snes,grids);
963:   }

965:   PetscOptionsEList("-snes_convergence_test","Convergence test","SNESSetConvergenceTest",convtests,2,"default",&indx,&flg);
966:   if (flg) {
967:     switch (indx) {
968:     case 0: SNESSetConvergenceTest(snes,SNESConvergedDefault,NULL,NULL); break;
969:     case 1: SNESSetConvergenceTest(snes,SNESConvergedSkip,NULL,NULL);    break;
970:     }
971:   }

973:   PetscOptionsEList("-snes_norm_schedule","SNES Norm schedule","SNESSetNormSchedule",SNESNormSchedules,5,"function",&indx,&flg);
974:   if (flg) { SNESSetNormSchedule(snes,(SNESNormSchedule)indx); }

976:   PetscOptionsEList("-snes_function_type","SNES Norm schedule","SNESSetFunctionType",SNESFunctionTypes,2,"unpreconditioned",&indx,&flg);
977:   if (flg) { SNESSetFunctionType(snes,(SNESFunctionType)indx); }

979:   kctx = (SNESKSPEW*)snes->kspconvctx;

981:   PetscOptionsBool("-snes_ksp_ew","Use Eisentat-Walker linear system convergence test","SNESKSPSetUseEW",snes->ksp_ewconv,&snes->ksp_ewconv,NULL);

983:   PetscOptionsInt("-snes_ksp_ew_version","Version 1, 2 or 3","SNESKSPSetParametersEW",kctx->version,&kctx->version,NULL);
984:   PetscOptionsReal("-snes_ksp_ew_rtol0","0 <= rtol0 < 1","SNESKSPSetParametersEW",kctx->rtol_0,&kctx->rtol_0,NULL);
985:   PetscOptionsReal("-snes_ksp_ew_rtolmax","0 <= rtolmax < 1","SNESKSPSetParametersEW",kctx->rtol_max,&kctx->rtol_max,NULL);
986:   PetscOptionsReal("-snes_ksp_ew_gamma","0 <= gamma <= 1","SNESKSPSetParametersEW",kctx->gamma,&kctx->gamma,NULL);
987:   PetscOptionsReal("-snes_ksp_ew_alpha","1 < alpha <= 2","SNESKSPSetParametersEW",kctx->alpha,&kctx->alpha,NULL);
988:   PetscOptionsReal("-snes_ksp_ew_alpha2","alpha2","SNESKSPSetParametersEW",kctx->alpha2,&kctx->alpha2,NULL);
989:   PetscOptionsReal("-snes_ksp_ew_threshold","0 < threshold < 1","SNESKSPSetParametersEW",kctx->threshold,&kctx->threshold,NULL);

991:   flg  = PETSC_FALSE;
992:   PetscOptionsBool("-snes_monitor_cancel","Remove all monitors","SNESMonitorCancel",flg,&flg,&set);
993:   if (set && flg) {SNESMonitorCancel(snes);}

995:   SNESMonitorSetFromOptions(snes,"-snes_monitor","Monitor norm of function","SNESMonitorDefault",SNESMonitorDefault,NULL);
996:   SNESMonitorSetFromOptions(snes,"-snes_monitor_short","Monitor norm of function with fewer digits","SNESMonitorDefaultShort",SNESMonitorDefaultShort,NULL);
997:   SNESMonitorSetFromOptions(snes,"-snes_monitor_range","Monitor range of elements of function","SNESMonitorRange",SNESMonitorRange,NULL);

999:   SNESMonitorSetFromOptions(snes,"-snes_monitor_ratio","Monitor ratios of the norm of function for consecutive steps","SNESMonitorRatio",SNESMonitorRatio,SNESMonitorRatioSetUp);
1000:   SNESMonitorSetFromOptions(snes,"-snes_monitor_field","Monitor norm of function (split into fields)","SNESMonitorDefaultField",SNESMonitorDefaultField,NULL);
1001:   SNESMonitorSetFromOptions(snes,"-snes_monitor_solution","View solution at each iteration","SNESMonitorSolution",SNESMonitorSolution,NULL);
1002:   SNESMonitorSetFromOptions(snes,"-snes_monitor_solution_update","View correction at each iteration","SNESMonitorSolutionUpdate",SNESMonitorSolutionUpdate,NULL);
1003:   SNESMonitorSetFromOptions(snes,"-snes_monitor_residual","View residual at each iteration","SNESMonitorResidual",SNESMonitorResidual,NULL);
1004:   SNESMonitorSetFromOptions(snes,"-snes_monitor_jacupdate_spectrum","Print the change in the spectrum of the Jacobian","SNESMonitorJacUpdateSpectrum",SNESMonitorJacUpdateSpectrum,NULL);
1005:   SNESMonitorSetFromOptions(snes,"-snes_monitor_fields","Monitor norm of function per field","SNESMonitorSet",SNESMonitorFields,NULL);

1007:   PetscOptionsString("-snes_monitor_python","Use Python function","SNESMonitorSet",NULL,monfilename,sizeof(monfilename),&flg);
1008:   if (flg) {PetscPythonMonitorSet((PetscObject)snes,monfilename);}

1010:   flg  = PETSC_FALSE;
1011:   PetscOptionsBool("-snes_monitor_lg_residualnorm","Plot function norm at each iteration","SNESMonitorLGResidualNorm",flg,&flg,NULL);
1012:   if (flg) {
1013:     PetscDrawLG ctx;

1015:     SNESMonitorLGCreate(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,400,300,&ctx);
1016:     SNESMonitorSet(snes,SNESMonitorLGResidualNorm,ctx,(PetscErrorCode (*)(void**))PetscDrawLGDestroy);
1017:   }
1018:   flg  = PETSC_FALSE;
1019:   PetscOptionsBool("-snes_monitor_lg_range","Plot function range at each iteration","SNESMonitorLGRange",flg,&flg,NULL);
1020:   if (flg) {
1021:     PetscViewer ctx;

1023:     PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,400,300,&ctx);
1024:     SNESMonitorSet(snes,SNESMonitorLGRange,ctx,(PetscErrorCode (*)(void**))PetscViewerDestroy);
1025:   }

1027:   flg  = PETSC_FALSE;
1028:   PetscOptionsBool("-snes_fd","Use finite differences (slow) to compute Jacobian","SNESComputeJacobianDefault",flg,&flg,NULL);
1029:   if (flg) {
1030:     void    *functx;
1031:     DM      dm;
1032:     DMSNES  sdm;
1033:     SNESGetDM(snes,&dm);
1034:     DMGetDMSNES(dm,&sdm);
1035:     sdm->jacobianctx = NULL;
1036:     SNESGetFunction(snes,NULL,NULL,&functx);
1037:     SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefault,functx);
1038:     PetscInfo(snes,"Setting default finite difference Jacobian matrix\n");
1039:   }

1041:   flg  = PETSC_FALSE;
1042:   PetscOptionsBool("-snes_fd_function","Use finite differences (slow) to compute function from user objective","SNESObjectiveComputeFunctionDefaultFD",flg,&flg,NULL);
1043:   if (flg) {
1044:     SNESSetFunction(snes,NULL,SNESObjectiveComputeFunctionDefaultFD,NULL);
1045:   }

1047:   flg  = PETSC_FALSE;
1048:   PetscOptionsBool("-snes_fd_color","Use finite differences with coloring to compute Jacobian","SNESComputeJacobianDefaultColor",flg,&flg,NULL);
1049:   if (flg) {
1050:     DM             dm;
1051:     DMSNES         sdm;
1052:     SNESGetDM(snes,&dm);
1053:     DMGetDMSNES(dm,&sdm);
1054:     sdm->jacobianctx = NULL;
1055:     SNESSetJacobian(snes,snes->jacobian,snes->jacobian_pre,SNESComputeJacobianDefaultColor,NULL);
1056:     PetscInfo(snes,"Setting default finite difference coloring Jacobian matrix\n");
1057:   }

1059:   flg  = PETSC_FALSE;
1060:   PetscOptionsBool("-snes_mf_operator","Use a Matrix-Free Jacobian with user-provided preconditioner matrix","SNESSetUseMatrixFree",PETSC_FALSE,&snes->mf_operator,&flg);
1061:   if (flg && snes->mf_operator) {
1062:     snes->mf_operator = PETSC_TRUE;
1063:     snes->mf          = PETSC_TRUE;
1064:   }
1065:   flg  = PETSC_FALSE;
1066:   PetscOptionsBool("-snes_mf","Use a Matrix-Free Jacobian with no preconditioner matrix","SNESSetUseMatrixFree",PETSC_FALSE,&snes->mf,&flg);
1067:   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
1068:   PetscOptionsInt("-snes_mf_version","Matrix-Free routines version 1 or 2","None",snes->mf_version,&snes->mf_version,NULL);

1070:   flg  = PETSC_FALSE;
1071:   SNESGetNPCSide(snes,&pcside);
1072:   PetscOptionsEnum("-snes_npc_side","SNES nonlinear preconditioner side","SNESSetNPCSide",PCSides,(PetscEnum)pcside,(PetscEnum*)&pcside,&flg);
1073:   if (flg) {SNESSetNPCSide(snes,pcside);}

1075: #if defined(PETSC_HAVE_SAWS)
1076:   /*
1077:     Publish convergence information using SAWs
1078:   */
1079:   flg  = PETSC_FALSE;
1080:   PetscOptionsBool("-snes_monitor_saws","Publish SNES progress using SAWs","SNESMonitorSet",flg,&flg,NULL);
1081:   if (flg) {
1082:     void *ctx;
1083:     SNESMonitorSAWsCreate(snes,&ctx);
1084:     SNESMonitorSet(snes,SNESMonitorSAWs,ctx,SNESMonitorSAWsDestroy);
1085:   }
1086: #endif
1087: #if defined(PETSC_HAVE_SAWS)
1088:   {
1089:   PetscBool set;
1090:   flg  = PETSC_FALSE;
1091:   PetscOptionsBool("-snes_saws_block","Block for SAWs at end of SNESSolve","PetscObjectSAWsBlock",((PetscObject)snes)->amspublishblock,&flg,&set);
1092:   if (set) {
1093:     PetscObjectSAWsSetBlock((PetscObject)snes,flg);
1094:   }
1095:   }
1096: #endif

1098:   for (i = 0; i < numberofsetfromoptions; i++) {
1099:     (*othersetfromoptions[i])(snes);
1100:   }

1102:   if (snes->ops->setfromoptions) {
1103:     (*snes->ops->setfromoptions)(PetscOptionsObject,snes);
1104:   }

1106:   /* process any options handlers added with PetscObjectAddOptionsHandler() */
1107:   PetscObjectProcessOptionsHandlers(PetscOptionsObject,(PetscObject)snes);
1108:   PetscOptionsEnd();

1110:   if (snes->linesearch) {
1111:     SNESGetLineSearch(snes, &snes->linesearch);
1112:     SNESLineSearchSetFromOptions(snes->linesearch);
1113:   }

1115:   if (snes->usesksp) {
1116:     if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
1117:     KSPSetOperators(snes->ksp,snes->jacobian,snes->jacobian_pre);
1118:     KSPSetFromOptions(snes->ksp);
1119:   }

1121:   /* if user has set the SNES NPC type via options database, create it. */
1122:   SNESGetOptionsPrefix(snes, &optionsprefix);
1123:   PetscOptionsHasName(((PetscObject)snes)->options,optionsprefix, "-npc_snes_type", &pcset);
1124:   if (pcset && (!snes->npc)) {
1125:     SNESGetNPC(snes, &snes->npc);
1126:   }
1127:   if (snes->npc) {
1128:     SNESSetFromOptions(snes->npc);
1129:   }
1130:   snes->setfromoptionscalled++;
1131:   return(0);
1132: }

1134: /*@
1135:    SNESResetFromOptions - Sets various SNES and KSP parameters from user options ONLY if the SNES was previously set from options

1137:    Collective on SNES

1139:    Input Parameter:
1140: .  snes - the SNES context

1142:    Level: beginner

1144: .seealso: SNESSetFromOptions(), SNESSetOptionsPrefix()
1145: @*/
1146: PetscErrorCode SNESResetFromOptions(SNES snes)
1147: {

1151:   if (snes->setfromoptionscalled) {SNESSetFromOptions(snes);}
1152:   return(0);
1153: }

1155: /*@C
1156:    SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
1157:    the nonlinear solvers.

1159:    Logically Collective on SNES

1161:    Input Parameters:
1162: +  snes - the SNES context
1163: .  compute - function to compute the context
1164: -  destroy - function to destroy the context

1166:    Level: intermediate

1168:    Notes:
1169:    This function is currently not available from Fortran.

1171: .seealso: SNESGetApplicationContext(), SNESSetComputeApplicationContext(), SNESGetApplicationContext()
1172: @*/
1173: PetscErrorCode  SNESSetComputeApplicationContext(SNES snes,PetscErrorCode (*compute)(SNES,void**),PetscErrorCode (*destroy)(void**))
1174: {
1177:   snes->ops->usercompute = compute;
1178:   snes->ops->userdestroy = destroy;
1179:   return(0);
1180: }

1182: /*@
1183:    SNESSetApplicationContext - Sets the optional user-defined context for
1184:    the nonlinear solvers.

1186:    Logically Collective on SNES

1188:    Input Parameters:
1189: +  snes - the SNES context
1190: -  usrP - optional user context

1192:    Level: intermediate

1194:    Fortran Notes:
1195:     To use this from Fortran you must write a Fortran interface definition for this
1196:     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

1198: .seealso: SNESGetApplicationContext()
1199: @*/
1200: PetscErrorCode  SNESSetApplicationContext(SNES snes,void *usrP)
1201: {
1203:   KSP            ksp;

1207:   SNESGetKSP(snes,&ksp);
1208:   KSPSetApplicationContext(ksp,usrP);
1209:   snes->user = usrP;
1210:   return(0);
1211: }

1213: /*@
1214:    SNESGetApplicationContext - Gets the user-defined context for the
1215:    nonlinear solvers.

1217:    Not Collective

1219:    Input Parameter:
1220: .  snes - SNES context

1222:    Output Parameter:
1223: .  usrP - user context

1225:    Fortran Notes:
1226:     To use this from Fortran you must write a Fortran interface definition for this
1227:     function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

1229:    Level: intermediate

1231: .seealso: SNESSetApplicationContext()
1232: @*/
1233: PetscErrorCode  SNESGetApplicationContext(SNES snes,void *usrP)
1234: {
1237:   *(void**)usrP = snes->user;
1238:   return(0);
1239: }

1241: /*@
1242:    SNESSetUseMatrixFree - indicates that SNES should use matrix free finite difference matrix vector products internally to apply the Jacobian.

1244:    Collective on SNES

1246:    Input Parameters:
1247: +  snes - SNES context
1248: .  mf_operator - use matrix-free only for the Amat used by SNESSetJacobian(), this means the user provided Pmat will continue to be used
1249: -  mf - use matrix-free for both the Amat and Pmat used by SNESSetJacobian(), both the Amat and Pmat set in SNESSetJacobian() will be ignored

1251:    Options Database:
1252: + -snes_mf - use matrix free for both the mat and pmat operator
1253: . -snes_mf_operator - use matrix free only for the mat operator
1254: . -snes_fd_color - compute the Jacobian via coloring and finite differences.
1255: - -snes_fd - compute the Jacobian via finite differences (slow)

1257:    Level: intermediate

1259:    Notes:
1260:       SNES supports three approaches for computing (approximate) Jacobians: user provided via SNESSetJacobian(), matrix free, and computing explictly with
1261:       finite differences and coloring using MatFDColoring. It is also possible to use automatic differentiation and the MatFDColoring object.

1263: .seealso:   SNESGetUseMatrixFree(), MatCreateSNESMF(), SNESComputeJacobianDefaultColor()
1264: @*/
1265: PetscErrorCode  SNESSetUseMatrixFree(SNES snes,PetscBool mf_operator,PetscBool mf)
1266: {
1271:   snes->mf          = mf_operator ? PETSC_TRUE : mf;
1272:   snes->mf_operator = mf_operator;
1273:   return(0);
1274: }

1276: /*@
1277:    SNESGetUseMatrixFree - indicates if the SNES uses matrix free finite difference matrix vector products to apply the Jacobian.

1279:    Collective on SNES

1281:    Input Parameter:
1282: .  snes - SNES context

1284:    Output Parameters:
1285: +  mf_operator - use matrix-free only for the Amat used by SNESSetJacobian(), this means the user provided Pmat will continue to be used
1286: -  mf - use matrix-free for both the Amat and Pmat used by SNESSetJacobian(), both the Amat and Pmat set in SNESSetJacobian() will be ignored

1288:    Options Database:
1289: + -snes_mf - use matrix free for both the mat and pmat operator
1290: - -snes_mf_operator - use matrix free only for the mat operator

1292:    Level: intermediate

1294: .seealso:   SNESSetUseMatrixFree(), MatCreateSNESMF()
1295: @*/
1296: PetscErrorCode  SNESGetUseMatrixFree(SNES snes,PetscBool *mf_operator,PetscBool *mf)
1297: {
1300:   if (mf)          *mf          = snes->mf;
1301:   if (mf_operator) *mf_operator = snes->mf_operator;
1302:   return(0);
1303: }

1305: /*@
1306:    SNESGetIterationNumber - Gets the number of nonlinear iterations completed
1307:    at this time.

1309:    Not Collective

1311:    Input Parameter:
1312: .  snes - SNES context

1314:    Output Parameter:
1315: .  iter - iteration number

1317:    Notes:
1318:    For example, during the computation of iteration 2 this would return 1.

1320:    This is useful for using lagged Jacobians (where one does not recompute the
1321:    Jacobian at each SNES iteration). For example, the code
1322: .vb
1323:       SNESGetIterationNumber(snes,&it);
1324:       if (!(it % 2)) {
1325:         [compute Jacobian here]
1326:       }
1327: .ve
1328:    can be used in your ComputeJacobian() function to cause the Jacobian to be
1329:    recomputed every second SNES iteration.

1331:    After the SNES solve is complete this will return the number of nonlinear iterations used.

1333:    Level: intermediate

1335: .seealso:   SNESGetLinearSolveIterations()
1336: @*/
1337: PetscErrorCode  SNESGetIterationNumber(SNES snes,PetscInt *iter)
1338: {
1342:   *iter = snes->iter;
1343:   return(0);
1344: }

1346: /*@
1347:    SNESSetIterationNumber - Sets the current iteration number.

1349:    Not Collective

1351:    Input Parameter:
1352: +  snes - SNES context
1353: -  iter - iteration number

1355:    Level: developer

1357: .seealso:   SNESGetLinearSolveIterations()
1358: @*/
1359: PetscErrorCode  SNESSetIterationNumber(SNES snes,PetscInt iter)
1360: {

1365:   PetscObjectSAWsTakeAccess((PetscObject)snes);
1366:   snes->iter = iter;
1367:   PetscObjectSAWsGrantAccess((PetscObject)snes);
1368:   return(0);
1369: }

1371: /*@
1372:    SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1373:    attempted by the nonlinear solver.

1375:    Not Collective

1377:    Input Parameter:
1378: .  snes - SNES context

1380:    Output Parameter:
1381: .  nfails - number of unsuccessful steps attempted

1383:    Notes:
1384:    This counter is reset to zero for each successive call to SNESSolve().

1386:    Level: intermediate

1388: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1389:           SNESSetMaxNonlinearStepFailures(), SNESGetMaxNonlinearStepFailures()
1390: @*/
1391: PetscErrorCode  SNESGetNonlinearStepFailures(SNES snes,PetscInt *nfails)
1392: {
1396:   *nfails = snes->numFailures;
1397:   return(0);
1398: }

1400: /*@
1401:    SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1402:    attempted by the nonlinear solver before it gives up.

1404:    Not Collective

1406:    Input Parameters:
1407: +  snes     - SNES context
1408: -  maxFails - maximum of unsuccessful steps

1410:    Level: intermediate

1412: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1413:           SNESGetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()
1414: @*/
1415: PetscErrorCode  SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1416: {
1419:   snes->maxFailures = maxFails;
1420:   return(0);
1421: }

1423: /*@
1424:    SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1425:    attempted by the nonlinear solver before it gives up.

1427:    Not Collective

1429:    Input Parameter:
1430: .  snes     - SNES context

1432:    Output Parameter:
1433: .  maxFails - maximum of unsuccessful steps

1435:    Level: intermediate

1437: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(),
1438:           SNESSetMaxNonlinearStepFailures(), SNESGetNonlinearStepFailures()

1440: @*/
1441: PetscErrorCode  SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1442: {
1446:   *maxFails = snes->maxFailures;
1447:   return(0);
1448: }

1450: /*@
1451:    SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1452:      done by SNES.

1454:    Not Collective

1456:    Input Parameter:
1457: .  snes     - SNES context

1459:    Output Parameter:
1460: .  nfuncs - number of evaluations

1462:    Level: intermediate

1464:    Notes:
1465:     Reset every time SNESSolve is called unless SNESSetCountersReset() is used.

1467: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(), SNESGetLinearSolveFailures(), SNESSetCountersReset()
1468: @*/
1469: PetscErrorCode  SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1470: {
1474:   *nfuncs = snes->nfuncs;
1475:   return(0);
1476: }

1478: /*@
1479:    SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1480:    linear solvers.

1482:    Not Collective

1484:    Input Parameter:
1485: .  snes - SNES context

1487:    Output Parameter:
1488: .  nfails - number of failed solves

1490:    Level: intermediate

1492:    Options Database Keys:
1493: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

1495:    Notes:
1496:    This counter is reset to zero for each successive call to SNESSolve().

1498: .seealso: SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures()
1499: @*/
1500: PetscErrorCode  SNESGetLinearSolveFailures(SNES snes,PetscInt *nfails)
1501: {
1505:   *nfails = snes->numLinearSolveFailures;
1506:   return(0);
1507: }

1509: /*@
1510:    SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1511:    allowed before SNES returns with a diverged reason of SNES_DIVERGED_LINEAR_SOLVE

1513:    Logically Collective on SNES

1515:    Input Parameters:
1516: +  snes     - SNES context
1517: -  maxFails - maximum allowed linear solve failures

1519:    Level: intermediate

1521:    Options Database Keys:
1522: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

1524:    Notes:
1525:     By default this is 0; that is SNES returns on the first failed linear solve

1527: .seealso: SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESGetLinearSolveIterations()
1528: @*/
1529: PetscErrorCode  SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1530: {
1534:   snes->maxLinearSolveFailures = maxFails;
1535:   return(0);
1536: }

1538: /*@
1539:    SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1540:      are allowed before SNES terminates

1542:    Not Collective

1544:    Input Parameter:
1545: .  snes     - SNES context

1547:    Output Parameter:
1548: .  maxFails - maximum of unsuccessful solves allowed

1550:    Level: intermediate

1552:    Notes:
1553:     By default this is 1; that is SNES returns on the first failed linear solve

1555: .seealso: SNESGetLinearSolveFailures(), SNESGetLinearSolveIterations(), SNESSetMaxLinearSolveFailures(),
1556: @*/
1557: PetscErrorCode  SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1558: {
1562:   *maxFails = snes->maxLinearSolveFailures;
1563:   return(0);
1564: }

1566: /*@
1567:    SNESGetLinearSolveIterations - Gets the total number of linear iterations
1568:    used by the nonlinear solver.

1570:    Not Collective

1572:    Input Parameter:
1573: .  snes - SNES context

1575:    Output Parameter:
1576: .  lits - number of linear iterations

1578:    Notes:
1579:    This counter is reset to zero for each successive call to SNESSolve() unless SNESSetCountersReset() is used.

1581:    If the linear solver fails inside the SNESSolve() the iterations for that call to the linear solver are not included. If you wish to count them
1582:    then call KSPGetIterationNumber() after the failed solve.

1584:    Level: intermediate

1586: .seealso:  SNESGetIterationNumber(), SNESGetLinearSolveFailures(), SNESGetMaxLinearSolveFailures(), SNESSetCountersReset()
1587: @*/
1588: PetscErrorCode  SNESGetLinearSolveIterations(SNES snes,PetscInt *lits)
1589: {
1593:   *lits = snes->linear_its;
1594:   return(0);
1595: }

1597: /*@
1598:    SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1599:    are reset every time SNESSolve() is called.

1601:    Logically Collective on SNES

1603:    Input Parameter:
1604: +  snes - SNES context
1605: -  reset - whether to reset the counters or not

1607:    Notes:
1608:    This defaults to PETSC_TRUE

1610:    Level: developer

1612: .seealso:  SNESGetNumberFunctionEvals(), SNESGetLinearSolveIterations(), SNESGetNPC()
1613: @*/
1614: PetscErrorCode  SNESSetCountersReset(SNES snes,PetscBool reset)
1615: {
1619:   snes->counters_reset = reset;
1620:   return(0);
1621: }


1624: /*@
1625:    SNESSetKSP - Sets a KSP context for the SNES object to use

1627:    Not Collective, but the SNES and KSP objects must live on the same MPI_Comm

1629:    Input Parameters:
1630: +  snes - the SNES context
1631: -  ksp - the KSP context

1633:    Notes:
1634:    The SNES object already has its KSP object, you can obtain with SNESGetKSP()
1635:    so this routine is rarely needed.

1637:    The KSP object that is already in the SNES object has its reference count
1638:    decreased by one.

1640:    Level: developer

1642: .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
1643: @*/
1644: PetscErrorCode  SNESSetKSP(SNES snes,KSP ksp)
1645: {

1652:   PetscObjectReference((PetscObject)ksp);
1653:   if (snes->ksp) {PetscObjectDereference((PetscObject)snes->ksp);}
1654:   snes->ksp = ksp;
1655:   return(0);
1656: }

1658: /* -----------------------------------------------------------*/
1659: /*@
1660:    SNESCreate - Creates a nonlinear solver context.

1662:    Collective

1664:    Input Parameters:
1665: .  comm - MPI communicator

1667:    Output Parameter:
1668: .  outsnes - the new SNES context

1670:    Options Database Keys:
1671: +   -snes_mf - Activates default matrix-free Jacobian-vector products,
1672:                and no preconditioning matrix
1673: .   -snes_mf_operator - Activates default matrix-free Jacobian-vector
1674:                products, and a user-provided preconditioning matrix
1675:                as set by SNESSetJacobian()
1676: -   -snes_fd - Uses (slow!) finite differences to compute Jacobian

1678:    Level: beginner

1680:    Developer Notes:
1681:     SNES always creates a KSP object even though many SNES methods do not use it. This is
1682:                     unfortunate and should be fixed at some point. The flag snes->usesksp indicates if the
1683:                     particular method does use KSP and regulates if the information about the KSP is printed
1684:                     in SNESView(). TSSetFromOptions() does call SNESSetFromOptions() which can lead to users being confused
1685:                     by help messages about meaningless SNES options.

1687:                     SNES always creates the snes->kspconvctx even though it is used by only one type. This should
1688:                     be fixed.

1690: .seealso: SNESSolve(), SNESDestroy(), SNES, SNESSetLagPreconditioner(), SNESSetLagJacobian()

1692: @*/
1693: PetscErrorCode  SNESCreate(MPI_Comm comm,SNES *outsnes)
1694: {
1696:   SNES           snes;
1697:   SNESKSPEW      *kctx;

1701:   *outsnes = NULL;
1702:   SNESInitializePackage();

1704:   PetscHeaderCreate(snes,SNES_CLASSID,"SNES","Nonlinear solver","SNES",comm,SNESDestroy,SNESView);

1706:   snes->ops->converged    = SNESConvergedDefault;
1707:   snes->usesksp           = PETSC_TRUE;
1708:   snes->tolerancesset     = PETSC_FALSE;
1709:   snes->max_its           = 50;
1710:   snes->max_funcs         = 10000;
1711:   snes->norm              = 0.0;
1712:   snes->xnorm             = 0.0;
1713:   snes->ynorm             = 0.0;
1714:   snes->normschedule      = SNES_NORM_ALWAYS;
1715:   snes->functype          = SNES_FUNCTION_DEFAULT;
1716: #if defined(PETSC_USE_REAL_SINGLE)
1717:   snes->rtol              = 1.e-5;
1718: #else
1719:   snes->rtol              = 1.e-8;
1720: #endif
1721:   snes->ttol              = 0.0;
1722: #if defined(PETSC_USE_REAL_SINGLE)
1723:   snes->abstol            = 1.e-25;
1724: #else
1725:   snes->abstol            = 1.e-50;
1726: #endif
1727: #if defined(PETSC_USE_REAL_SINGLE)
1728:   snes->stol              = 1.e-5;
1729: #else
1730:   snes->stol              = 1.e-8;
1731: #endif
1732: #if defined(PETSC_USE_REAL_SINGLE)
1733:   snes->deltatol          = 1.e-6;
1734: #else
1735:   snes->deltatol          = 1.e-12;
1736: #endif
1737:   snes->divtol            = 1.e4;
1738:   snes->rnorm0            = 0;
1739:   snes->nfuncs            = 0;
1740:   snes->numFailures       = 0;
1741:   snes->maxFailures       = 1;
1742:   snes->linear_its        = 0;
1743:   snes->lagjacobian       = 1;
1744:   snes->jac_iter          = 0;
1745:   snes->lagjac_persist    = PETSC_FALSE;
1746:   snes->lagpreconditioner = 1;
1747:   snes->pre_iter          = 0;
1748:   snes->lagpre_persist    = PETSC_FALSE;
1749:   snes->numbermonitors    = 0;
1750:   snes->data              = NULL;
1751:   snes->setupcalled       = PETSC_FALSE;
1752:   snes->ksp_ewconv        = PETSC_FALSE;
1753:   snes->nwork             = 0;
1754:   snes->work              = NULL;
1755:   snes->nvwork            = 0;
1756:   snes->vwork             = NULL;
1757:   snes->conv_hist_len     = 0;
1758:   snes->conv_hist_max     = 0;
1759:   snes->conv_hist         = NULL;
1760:   snes->conv_hist_its     = NULL;
1761:   snes->conv_hist_reset   = PETSC_TRUE;
1762:   snes->counters_reset    = PETSC_TRUE;
1763:   snes->vec_func_init_set = PETSC_FALSE;
1764:   snes->reason            = SNES_CONVERGED_ITERATING;
1765:   snes->npcside           = PC_RIGHT;
1766:   snes->setfromoptionscalled = 0;

1768:   snes->mf          = PETSC_FALSE;
1769:   snes->mf_operator = PETSC_FALSE;
1770:   snes->mf_version  = 1;

1772:   snes->numLinearSolveFailures = 0;
1773:   snes->maxLinearSolveFailures = 1;

1775:   snes->vizerotolerance = 1.e-8;
1776:   snes->checkjacdomainerror = PetscDefined(USE_DEBUG) ? PETSC_TRUE : PETSC_FALSE;

1778:   /* Set this to true if the implementation of SNESSolve_XXX does compute the residual at the final solution. */
1779:   snes->alwayscomputesfinalresidual = PETSC_FALSE;

1781:   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1782:   PetscNewLog(snes,&kctx);

1784:   snes->kspconvctx  = (void*)kctx;
1785:   kctx->version     = 2;
1786:   kctx->rtol_0      = .3; /* Eisenstat and Walker suggest rtol_0=.5, but
1787:                              this was too large for some test cases */
1788:   kctx->rtol_last   = 0.0;
1789:   kctx->rtol_max    = .9;
1790:   kctx->gamma       = 1.0;
1791:   kctx->alpha       = .5*(1.0 + PetscSqrtReal(5.0));
1792:   kctx->alpha2      = kctx->alpha;
1793:   kctx->threshold   = .1;
1794:   kctx->lresid_last = 0.0;
1795:   kctx->norm_last   = 0.0;

1797:   *outsnes = snes;
1798:   return(0);
1799: }

1801: /*MC
1802:     SNESFunction - Functional form used to convey the nonlinear function to be solved by SNES

1804:      Synopsis:
1805:      #include "petscsnes.h"
1806:      PetscErrorCode SNESFunction(SNES snes,Vec x,Vec f,void *ctx);

1808:      Collective on snes

1810:      Input Parameters:
1811: +     snes - the SNES context
1812: .     x    - state at which to evaluate residual
1813: -     ctx     - optional user-defined function context, passed in with SNESSetFunction()

1815:      Output Parameter:
1816: .     f  - vector to put residual (function value)

1818:    Level: intermediate

1820: .seealso:   SNESSetFunction(), SNESGetFunction()
1821: M*/

1823: /*@C
1824:    SNESSetFunction - Sets the function evaluation routine and function
1825:    vector for use by the SNES routines in solving systems of nonlinear
1826:    equations.

1828:    Logically Collective on SNES

1830:    Input Parameters:
1831: +  snes - the SNES context
1832: .  r - vector to store function value
1833: .  f - function evaluation routine; see SNESFunction for calling sequence details
1834: -  ctx - [optional] user-defined context for private data for the
1835:          function evaluation routine (may be NULL)

1837:    Notes:
1838:    The Newton-like methods typically solve linear systems of the form
1839: $      f'(x) x = -f(x),
1840:    where f'(x) denotes the Jacobian matrix and f(x) is the function.

1842:    Level: beginner

1844: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetPicard(), SNESFunction
1845: @*/
1846: PetscErrorCode  SNESSetFunction(SNES snes,Vec r,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
1847: {
1849:   DM             dm;

1853:   if (r) {
1856:     PetscObjectReference((PetscObject)r);
1857:     VecDestroy(&snes->vec_func);

1859:     snes->vec_func = r;
1860:   }
1861:   SNESGetDM(snes,&dm);
1862:   DMSNESSetFunction(dm,f,ctx);
1863:   return(0);
1864: }


1867: /*@C
1868:    SNESSetInitialFunction - Sets the function vector to be used as the
1869:    function norm at the initialization of the method.  In some
1870:    instances, the user has precomputed the function before calling
1871:    SNESSolve.  This function allows one to avoid a redundant call
1872:    to SNESComputeFunction in that case.

1874:    Logically Collective on SNES

1876:    Input Parameters:
1877: +  snes - the SNES context
1878: -  f - vector to store function value

1880:    Notes:
1881:    This should not be modified during the solution procedure.

1883:    This is used extensively in the SNESFAS hierarchy and in nonlinear preconditioning.

1885:    Level: developer

1887: .seealso: SNESSetFunction(), SNESComputeFunction(), SNESSetInitialFunctionNorm()
1888: @*/
1889: PetscErrorCode  SNESSetInitialFunction(SNES snes, Vec f)
1890: {
1892:   Vec            vec_func;

1898:   if (snes->npcside== PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
1899:     snes->vec_func_init_set = PETSC_FALSE;
1900:     return(0);
1901:   }
1902:   SNESGetFunction(snes,&vec_func,NULL,NULL);
1903:   VecCopy(f, vec_func);

1905:   snes->vec_func_init_set = PETSC_TRUE;
1906:   return(0);
1907: }

1909: /*@
1910:    SNESSetNormSchedule - Sets the SNESNormSchedule used in covergence and monitoring
1911:    of the SNES method.

1913:    Logically Collective on SNES

1915:    Input Parameters:
1916: +  snes - the SNES context
1917: -  normschedule - the frequency of norm computation

1919:    Options Database Key:
1920: .  -snes_norm_schedule <none, always, initialonly, finalonly, initalfinalonly>

1922:    Notes:
1923:    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
1924:    of the nonlinear function and the taking of its norm at every iteration to
1925:    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1926:    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
1927:    may either be monitored for convergence or not.  As these are often used as nonlinear
1928:    preconditioners, monitoring the norm of their error is not a useful enterprise within
1929:    their solution.

1931:    Level: developer

1933: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1934: @*/
1935: PetscErrorCode  SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
1936: {
1939:   snes->normschedule = normschedule;
1940:   return(0);
1941: }


1944: /*@
1945:    SNESGetNormSchedule - Gets the SNESNormSchedule used in covergence and monitoring
1946:    of the SNES method.

1948:    Logically Collective on SNES

1950:    Input Parameters:
1951: +  snes - the SNES context
1952: -  normschedule - the type of the norm used

1954:    Level: advanced

1956: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1957: @*/
1958: PetscErrorCode  SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
1959: {
1962:   *normschedule = snes->normschedule;
1963:   return(0);
1964: }


1967: /*@
1968:   SNESSetFunctionNorm - Sets the last computed residual norm.

1970:   Logically Collective on SNES

1972:   Input Parameters:
1973: + snes - the SNES context

1975: - normschedule - the frequency of norm computation

1977:   Level: developer

1979: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
1980: @*/
1981: PetscErrorCode SNESSetFunctionNorm(SNES snes, PetscReal norm)
1982: {
1985:   snes->norm = norm;
1986:   return(0);
1987: }

1989: /*@
1990:   SNESGetFunctionNorm - Gets the last computed norm of the residual

1992:   Not Collective

1994:   Input Parameter:
1995: . snes - the SNES context

1997:   Output Parameter:
1998: . norm - the last computed residual norm

2000:   Level: developer

2002: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
2003: @*/
2004: PetscErrorCode SNESGetFunctionNorm(SNES snes, PetscReal *norm)
2005: {
2009:   *norm = snes->norm;
2010:   return(0);
2011: }

2013: /*@
2014:   SNESGetUpdateNorm - Gets the last computed norm of the Newton update

2016:   Not Collective

2018:   Input Parameter:
2019: . snes - the SNES context

2021:   Output Parameter:
2022: . ynorm - the last computed update norm

2024:   Level: developer

2026: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), SNESGetFunctionNorm()
2027: @*/
2028: PetscErrorCode SNESGetUpdateNorm(SNES snes, PetscReal *ynorm)
2029: {
2033:   *ynorm = snes->ynorm;
2034:   return(0);
2035: }

2037: /*@
2038:   SNESGetSolutionNorm - Gets the last computed norm of the solution

2040:   Not Collective

2042:   Input Parameter:
2043: . snes - the SNES context

2045:   Output Parameter:
2046: . xnorm - the last computed solution norm

2048:   Level: developer

2050: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), SNESGetFunctionNorm(), SNESGetUpdateNorm()
2051: @*/
2052: PetscErrorCode SNESGetSolutionNorm(SNES snes, PetscReal *xnorm)
2053: {
2057:   *xnorm = snes->xnorm;
2058:   return(0);
2059: }

2061: /*@C
2062:    SNESSetFunctionType - Sets the SNESNormSchedule used in covergence and monitoring
2063:    of the SNES method.

2065:    Logically Collective on SNES

2067:    Input Parameters:
2068: +  snes - the SNES context
2069: -  normschedule - the frequency of norm computation

2071:    Notes:
2072:    Only certain SNES methods support certain SNESNormSchedules.  Most require evaluation
2073:    of the nonlinear function and the taking of its norm at every iteration to
2074:    even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
2075:    (SNESNGS) and the like do not require the norm of the function to be computed, and therfore
2076:    may either be monitored for convergence or not.  As these are often used as nonlinear
2077:    preconditioners, monitoring the norm of their error is not a useful enterprise within
2078:    their solution.

2080:    Level: developer

2082: .seealso: SNESGetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
2083: @*/
2084: PetscErrorCode  SNESSetFunctionType(SNES snes, SNESFunctionType type)
2085: {
2088:   snes->functype = type;
2089:   return(0);
2090: }


2093: /*@C
2094:    SNESGetFunctionType - Gets the SNESNormSchedule used in covergence and monitoring
2095:    of the SNES method.

2097:    Logically Collective on SNES

2099:    Input Parameters:
2100: +  snes - the SNES context
2101: -  normschedule - the type of the norm used

2103:    Level: advanced

2105: .seealso: SNESSetNormSchedule(), SNESComputeFunction(), VecNorm(), SNESSetFunction(), SNESSetInitialFunction(), SNESNormSchedule
2106: @*/
2107: PetscErrorCode  SNESGetFunctionType(SNES snes, SNESFunctionType *type)
2108: {
2111:   *type = snes->functype;
2112:   return(0);
2113: }

2115: /*MC
2116:     SNESNGSFunction - function used to convey a Gauss-Seidel sweep on the nonlinear function

2118:      Synopsis:
2119: #include <petscsnes.h>
2120: $    SNESNGSFunction(SNES snes,Vec x,Vec b,void *ctx);

2122:      Collective on snes

2124:      Input Parameters:
2125: +  X   - solution vector
2126: .  B   - RHS vector
2127: -  ctx - optional user-defined Gauss-Seidel context

2129:      Output Parameter:
2130: .  X   - solution vector

2132:    Level: intermediate

2134: .seealso:   SNESSetNGS(), SNESGetNGS()
2135: M*/

2137: /*@C
2138:    SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
2139:    use with composed nonlinear solvers.

2141:    Input Parameters:
2142: +  snes   - the SNES context
2143: .  f - function evaluation routine to apply Gauss-Seidel see SNESNGSFunction
2144: -  ctx    - [optional] user-defined context for private data for the
2145:             smoother evaluation routine (may be NULL)

2147:    Notes:
2148:    The NGS routines are used by the composed nonlinear solver to generate
2149:     a problem appropriate update to the solution, particularly FAS.

2151:    Level: intermediate

2153: .seealso: SNESGetFunction(), SNESComputeNGS()
2154: @*/
2155: PetscErrorCode SNESSetNGS(SNES snes,PetscErrorCode (*f)(SNES,Vec,Vec,void*),void *ctx)
2156: {
2158:   DM             dm;

2162:   SNESGetDM(snes,&dm);
2163:   DMSNESSetNGS(dm,f,ctx);
2164:   return(0);
2165: }

2167: PetscErrorCode SNESPicardComputeFunction(SNES snes,Vec x,Vec f,void *ctx)
2168: {
2170:   DM             dm;
2171:   DMSNES         sdm;

2174:   SNESGetDM(snes,&dm);
2175:   DMGetDMSNES(dm,&sdm);
2176:   if (!sdm->ops->computepfunction) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard function.");
2177:   if (!sdm->ops->computepjacobian) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetPicard() to provide Picard Jacobian.");
2178:   /*  A(x)*x - b(x) */
2179:   PetscStackPush("SNES Picard user function");
2180:   (*sdm->ops->computepfunction)(snes,x,f,sdm->pctx);
2181:   PetscStackPop;
2182:   PetscStackPush("SNES Picard user Jacobian");
2183:   (*sdm->ops->computepjacobian)(snes,x,snes->jacobian,snes->jacobian_pre,sdm->pctx);
2184:   PetscStackPop;
2185:   VecScale(f,-1.0);
2186:   MatMultAdd(snes->jacobian,x,f,f);
2187:   return(0);
2188: }

2190: PetscErrorCode SNESPicardComputeJacobian(SNES snes,Vec x1,Mat J,Mat B,void *ctx)
2191: {
2193:   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
2194:   return(0);
2195: }

2197: /*@C
2198:    SNESSetPicard - Use SNES to solve the semilinear-system A(x) x = b(x) via a Picard type iteration (Picard linearization)

2200:    Logically Collective on SNES

2202:    Input Parameters:
2203: +  snes - the SNES context
2204: .  r - vector to store function value
2205: .  b - function evaluation routine
2206: .  Amat - matrix with which A(x) x - b(x) is to be computed
2207: .  Pmat - matrix from which preconditioner is computed (usually the same as Amat)
2208: .  J  - function to compute matrix value, see SNESJacobianFunction for details on its calling sequence
2209: -  ctx - [optional] user-defined context for private data for the
2210:          function evaluation routine (may be NULL)

2212:    Notes:
2213:     We do not recomemend using this routine. It is far better to provide the nonlinear function F() and some approximation to the Jacobian and use
2214:     an approximate Newton solver. This interface is provided to allow porting/testing a previous Picard based code in PETSc before converting it to approximate Newton.

2216:     One can call SNESSetPicard() or SNESSetFunction() (and possibly SNESSetJacobian()) but cannot call both

2218: $     Solves the equation A(x) x = b(x) via the defect correction algorithm A(x^{n}) (x^{n+1} - x^{n}) = b(x^{n}) - A(x^{n})x^{n}
2219: $     Note that when an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = b(x^{n}) iteration.

2221:      Run with -snes_mf_operator to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.

2223:    We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
2224:    the direct Picard iteration A(x^n) x^{n+1} = b(x^n)

2226:    There is some controversity over the definition of a Picard iteration for nonlinear systems but almost everyone agrees that it involves a linear solve and some
2227:    believe it is the iteration  A(x^{n}) x^{n+1} = b(x^{n}) hence we use the name Picard. If anyone has an authoritative  reference that defines the Picard iteration
2228:    different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).

2230:    Level: intermediate

2232: .seealso: SNESGetFunction(), SNESSetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESGetPicard(), SNESLineSearchPreCheckPicard(), SNESJacobianFunction
2233: @*/
2234: PetscErrorCode  SNESSetPicard(SNES snes,Vec r,PetscErrorCode (*b)(SNES,Vec,Vec,void*),Mat Amat, Mat Pmat, PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2235: {
2237:   DM             dm;

2241:   SNESGetDM(snes, &dm);
2242:   DMSNESSetPicard(dm,b,J,ctx);
2243:   SNESSetFunction(snes,r,SNESPicardComputeFunction,ctx);
2244:   SNESSetJacobian(snes,Amat,Pmat,SNESPicardComputeJacobian,ctx);
2245:   return(0);
2246: }

2248: /*@C
2249:    SNESGetPicard - Returns the context for the Picard iteration

2251:    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.

2253:    Input Parameter:
2254: .  snes - the SNES context

2256:    Output Parameter:
2257: +  r - the function (or NULL)
2258: .  f - the function (or NULL); see SNESFunction for calling sequence details
2259: .  Amat - the matrix used to defined the operation A(x) x - b(x) (or NULL)
2260: .  Pmat  - the matrix from which the preconditioner will be constructed (or NULL)
2261: .  J - the function for matrix evaluation (or NULL); see SNESJacobianFunction for calling sequence details
2262: -  ctx - the function context (or NULL)

2264:    Level: advanced

2266: .seealso: SNESSetPicard(), SNESGetFunction(), SNESGetJacobian(), SNESGetDM(), SNESFunction, SNESJacobianFunction
2267: @*/
2268: PetscErrorCode  SNESGetPicard(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),Mat *Amat, Mat *Pmat, PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
2269: {
2271:   DM             dm;

2275:   SNESGetFunction(snes,r,NULL,NULL);
2276:   SNESGetJacobian(snes,Amat,Pmat,NULL,NULL);
2277:   SNESGetDM(snes,&dm);
2278:   DMSNESGetPicard(dm,f,J,ctx);
2279:   return(0);
2280: }

2282: /*@C
2283:    SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the problem

2285:    Logically Collective on SNES

2287:    Input Parameters:
2288: +  snes - the SNES context
2289: .  func - function evaluation routine
2290: -  ctx - [optional] user-defined context for private data for the
2291:          function evaluation routine (may be NULL)

2293:    Calling sequence of func:
2294: $    func (SNES snes,Vec x,void *ctx);

2296: .  f - function vector
2297: -  ctx - optional user-defined function context

2299:    Level: intermediate

2301: .seealso: SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian()
2302: @*/
2303: PetscErrorCode  SNESSetComputeInitialGuess(SNES snes,PetscErrorCode (*func)(SNES,Vec,void*),void *ctx)
2304: {
2307:   if (func) snes->ops->computeinitialguess = func;
2308:   if (ctx)  snes->initialguessP            = ctx;
2309:   return(0);
2310: }

2312: /* --------------------------------------------------------------- */
2313: /*@C
2314:    SNESGetRhs - Gets the vector for solving F(x) = rhs. If rhs is not set
2315:    it assumes a zero right hand side.

2317:    Logically Collective on SNES

2319:    Input Parameter:
2320: .  snes - the SNES context

2322:    Output Parameter:
2323: .  rhs - the right hand side vector or NULL if the right hand side vector is null

2325:    Level: intermediate

2327: .seealso: SNESGetSolution(), SNESGetFunction(), SNESComputeFunction(), SNESSetJacobian(), SNESSetFunction()
2328: @*/
2329: PetscErrorCode  SNESGetRhs(SNES snes,Vec *rhs)
2330: {
2334:   *rhs = snes->vec_rhs;
2335:   return(0);
2336: }

2338: /*@
2339:    SNESComputeFunction - Calls the function that has been set with SNESSetFunction().

2341:    Collective on SNES

2343:    Input Parameters:
2344: +  snes - the SNES context
2345: -  x - input vector

2347:    Output Parameter:
2348: .  y - function vector, as set by SNESSetFunction()

2350:    Notes:
2351:    SNESComputeFunction() is typically used within nonlinear solvers
2352:    implementations, so most users would not generally call this routine
2353:    themselves.

2355:    Level: developer

2357: .seealso: SNESSetFunction(), SNESGetFunction()
2358: @*/
2359: PetscErrorCode  SNESComputeFunction(SNES snes,Vec x,Vec y)
2360: {
2362:   DM             dm;
2363:   DMSNES         sdm;

2371:   VecValidValues(x,2,PETSC_TRUE);

2373:   SNESGetDM(snes,&dm);
2374:   DMGetDMSNES(dm,&sdm);
2375:   if (sdm->ops->computefunction) {
2376:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2377:       PetscLogEventBegin(SNES_FunctionEval,snes,x,y,0);
2378:     }
2379:     VecLockReadPush(x);
2380:     PetscStackPush("SNES user function");
2381:     /* ensure domainerror is false prior to computefunction evaluation (may not have been reset) */
2382:     snes->domainerror = PETSC_FALSE;
2383:     (*sdm->ops->computefunction)(snes,x,y,sdm->functionctx);
2384:     PetscStackPop;
2385:     VecLockReadPop(x);
2386:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) {
2387:       PetscLogEventEnd(SNES_FunctionEval,snes,x,y,0);
2388:     }
2389:   } else if (snes->vec_rhs) {
2390:     MatMult(snes->jacobian, x, y);
2391:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2392:   if (snes->vec_rhs) {
2393:     VecAXPY(y,-1.0,snes->vec_rhs);
2394:   }
2395:   snes->nfuncs++;
2396:   /*
2397:      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
2398:      propagate the value to all processes
2399:   */
2400:   if (snes->domainerror) {
2401:     VecSetInf(y);
2402:   }
2403:   return(0);
2404: }

2406: /*@
2407:    SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  SNESSetNGS().

2409:    Collective on SNES

2411:    Input Parameters:
2412: +  snes - the SNES context
2413: .  x - input vector
2414: -  b - rhs vector

2416:    Output Parameter:
2417: .  x - new solution vector

2419:    Notes:
2420:    SNESComputeNGS() is typically used within composed nonlinear solver
2421:    implementations, so most users would not generally call this routine
2422:    themselves.

2424:    Level: developer

2426: .seealso: SNESSetNGS(), SNESComputeFunction()
2427: @*/
2428: PetscErrorCode  SNESComputeNGS(SNES snes,Vec b,Vec x)
2429: {
2431:   DM             dm;
2432:   DMSNES         sdm;

2440:   if (b) {VecValidValues(b,2,PETSC_TRUE);}
2441:   PetscLogEventBegin(SNES_NGSEval,snes,x,b,0);
2442:   SNESGetDM(snes,&dm);
2443:   DMGetDMSNES(dm,&sdm);
2444:   if (sdm->ops->computegs) {
2445:     if (b) {VecLockReadPush(b);}
2446:     PetscStackPush("SNES user NGS");
2447:     (*sdm->ops->computegs)(snes,x,b,sdm->gsctx);
2448:     PetscStackPop;
2449:     if (b) {VecLockReadPop(b);}
2450:   } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
2451:   PetscLogEventEnd(SNES_NGSEval,snes,x,b,0);
2452:   return(0);
2453: }

2455: PetscErrorCode SNESTestJacobian(SNES snes)
2456: {
2457:   Mat               A,B,C,D,jacobian;
2458:   Vec               x = snes->vec_sol,f = snes->vec_func;
2459:   PetscErrorCode    ierr;
2460:   PetscReal         nrm,gnorm;
2461:   PetscReal         threshold = 1.e-5;
2462:   MatType           mattype;
2463:   PetscInt          m,n,M,N;
2464:   void              *functx;
2465:   PetscBool         complete_print = PETSC_FALSE,threshold_print = PETSC_FALSE,test = PETSC_FALSE,flg,istranspose;
2466:   PetscViewer       viewer,mviewer;
2467:   MPI_Comm          comm;
2468:   PetscInt          tabs;
2469:   static PetscBool  directionsprinted = PETSC_FALSE;
2470:   PetscViewerFormat format;

2473:   PetscObjectOptionsBegin((PetscObject)snes);
2474:   PetscOptionsName("-snes_test_jacobian","Compare hand-coded and finite difference Jacobians","None",&test);
2475:   PetscOptionsReal("-snes_test_jacobian", "Threshold for element difference between hand-coded and finite difference being meaningful", "None", threshold, &threshold,NULL);
2476:   PetscOptionsViewer("-snes_test_jacobian_view","View difference between hand-coded and finite difference Jacobians element entries","None",&mviewer,&format,&complete_print);
2477:   if (!complete_print) {
2478:     PetscOptionsDeprecated("-snes_test_jacobian_display","-snes_test_jacobian_view","3.13",NULL);
2479:     PetscOptionsViewer("-snes_test_jacobian_display","Display difference between hand-coded and finite difference Jacobians","None",&mviewer,&format,&complete_print);
2480:   }
2481:   /* for compatibility with PETSc 3.9 and older. */
2482:   PetscOptionsDeprecated("-snes_test_jacobian_display_threshold","-snes_test_jacobian","3.13","-snes_test_jacobian accepts an optional threshold (since v3.10)");
2483:   PetscOptionsReal("-snes_test_jacobian_display_threshold", "Display difference between hand-coded and finite difference Jacobians which exceed input threshold", "None", threshold, &threshold, &threshold_print);
2484:   PetscOptionsEnd();
2485:   if (!test) return(0);

2487:   PetscObjectGetComm((PetscObject)snes,&comm);
2488:   PetscViewerASCIIGetStdout(comm,&viewer);
2489:   PetscViewerASCIIGetTab(viewer, &tabs);
2490:   PetscViewerASCIISetTab(viewer, ((PetscObject)snes)->tablevel);
2491:   PetscViewerASCIIPrintf(viewer,"  ---------- Testing Jacobian -------------\n");
2492:   if (!complete_print && !directionsprinted) {
2493:     PetscViewerASCIIPrintf(viewer,"  Run with -snes_test_jacobian_view and optionally -snes_test_jacobian <threshold> to show difference\n");
2494:     PetscViewerASCIIPrintf(viewer,"    of hand-coded and finite difference Jacobian entries greater than <threshold>.\n");
2495:   }
2496:   if (!directionsprinted) {
2497:     PetscViewerASCIIPrintf(viewer,"  Testing hand-coded Jacobian, if (for double precision runs) ||J - Jfd||_F/||J||_F is\n");
2498:     PetscViewerASCIIPrintf(viewer,"    O(1.e-8), the hand-coded Jacobian is probably correct.\n");
2499:     directionsprinted = PETSC_TRUE;
2500:   }
2501:   if (complete_print) {
2502:     PetscViewerPushFormat(mviewer,format);
2503:   }

2505:   PetscObjectTypeCompare((PetscObject)snes->jacobian,MATMFFD,&flg);
2506:   if (!flg) jacobian = snes->jacobian;
2507:   else jacobian = snes->jacobian_pre;

2509:   if (!x) {
2510:     MatCreateVecs(jacobian, &x, NULL);
2511:   } else {
2512:     PetscObjectReference((PetscObject) x);
2513:   }
2514:   if (!f) {
2515:     VecDuplicate(x, &f);
2516:   } else {
2517:     PetscObjectReference((PetscObject) f);
2518:   }
2519:   /* evaluate the function at this point because SNESComputeJacobianDefault() assumes that the function has been evaluated and put into snes->vec_func */
2520:   SNESComputeFunction(snes,x,f);
2521:   VecDestroy(&f);
2522:   PetscObjectTypeCompare((PetscObject)snes,SNESKSPTRANSPOSEONLY,&istranspose);
2523:   while (jacobian) {
2524:     Mat JT = NULL, Jsave = NULL;

2526:     if (istranspose) {
2527:       MatCreateTranspose(jacobian,&JT);
2528:       Jsave = jacobian;
2529:       jacobian = JT;
2530:     }
2531:     PetscObjectBaseTypeCompareAny((PetscObject)jacobian,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPISBAIJ,"");
2532:     if (flg) {
2533:       A    = jacobian;
2534:       PetscObjectReference((PetscObject)A);
2535:     } else {
2536:       MatComputeOperator(jacobian,MATAIJ,&A);
2537:     }

2539:     MatGetType(A,&mattype);
2540:     MatGetSize(A,&M,&N);
2541:     MatGetLocalSize(A,&m,&n);
2542:     MatCreate(PetscObjectComm((PetscObject)A),&B);
2543:     MatSetType(B,mattype);
2544:     MatSetSizes(B,m,n,M,N);
2545:     MatSetBlockSizesFromMats(B,A,A);
2546:     MatSetUp(B);
2547:     MatSetOption(B,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE);

2549:     SNESGetFunction(snes,NULL,NULL,&functx);
2550:     SNESComputeJacobianDefault(snes,x,B,B,functx);

2552:     MatDuplicate(B,MAT_COPY_VALUES,&D);
2553:     MatAYPX(D,-1.0,A,DIFFERENT_NONZERO_PATTERN);
2554:     MatNorm(D,NORM_FROBENIUS,&nrm);
2555:     MatNorm(A,NORM_FROBENIUS,&gnorm);
2556:     MatDestroy(&D);
2557:     if (!gnorm) gnorm = 1; /* just in case */
2558:     PetscViewerASCIIPrintf(viewer,"  ||J - Jfd||_F/||J||_F = %g, ||J - Jfd||_F = %g\n",(double)(nrm/gnorm),(double)nrm);

2560:     if (complete_print) {
2561:       PetscViewerASCIIPrintf(viewer,"  Hand-coded Jacobian ----------\n");
2562:       MatView(A,mviewer);
2563:       PetscViewerASCIIPrintf(viewer,"  Finite difference Jacobian ----------\n");
2564:       MatView(B,mviewer);
2565:     }

2567:     if (threshold_print || complete_print) {
2568:       PetscInt          Istart, Iend, *ccols, bncols, cncols, j, row;
2569:       PetscScalar       *cvals;
2570:       const PetscInt    *bcols;
2571:       const PetscScalar *bvals;

2573:       MatCreate(PetscObjectComm((PetscObject)A),&C);
2574:       MatSetType(C,mattype);
2575:       MatSetSizes(C,m,n,M,N);
2576:       MatSetBlockSizesFromMats(C,A,A);
2577:       MatSetUp(C);
2578:       MatSetOption(C,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE);

2580:       MatAYPX(B,-1.0,A,DIFFERENT_NONZERO_PATTERN);
2581:       MatGetOwnershipRange(B,&Istart,&Iend);

2583:       for (row = Istart; row < Iend; row++) {
2584:         MatGetRow(B,row,&bncols,&bcols,&bvals);
2585:         PetscMalloc2(bncols,&ccols,bncols,&cvals);
2586:         for (j = 0, cncols = 0; j < bncols; j++) {
2587:           if (PetscAbsScalar(bvals[j]) > threshold) {
2588:             ccols[cncols] = bcols[j];
2589:             cvals[cncols] = bvals[j];
2590:             cncols += 1;
2591:           }
2592:         }
2593:         if (cncols) {
2594:           MatSetValues(C,1,&row,cncols,ccols,cvals,INSERT_VALUES);
2595:         }
2596:         MatRestoreRow(B,row,&bncols,&bcols,&bvals);
2597:         PetscFree2(ccols,cvals);
2598:       }
2599:       MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
2600:       MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
2601:       PetscViewerASCIIPrintf(viewer,"  Hand-coded minus finite-difference Jacobian with tolerance %g ----------\n",(double)threshold);
2602:       MatView(C,complete_print ? mviewer : viewer);
2603:       MatDestroy(&C);
2604:     }
2605:     MatDestroy(&A);
2606:     MatDestroy(&B);
2607:     MatDestroy(&JT);
2608:     if (Jsave) jacobian = Jsave;
2609:     if (jacobian != snes->jacobian_pre) {
2610:       jacobian = snes->jacobian_pre;
2611:       PetscViewerASCIIPrintf(viewer,"  ---------- Testing Jacobian for preconditioner -------------\n");
2612:     }
2613:     else jacobian = NULL;
2614:   }
2615:   VecDestroy(&x);
2616:   if (complete_print) {
2617:     PetscViewerPopFormat(mviewer);
2618:   }
2619:   if (mviewer) { PetscViewerDestroy(&mviewer); }
2620:   PetscViewerASCIISetTab(viewer,tabs);
2621:   return(0);
2622: }

2624: /*@
2625:    SNESComputeJacobian - Computes the Jacobian matrix that has been set with SNESSetJacobian().

2627:    Collective on SNES

2629:    Input Parameters:
2630: +  snes - the SNES context
2631: -  x - input vector

2633:    Output Parameters:
2634: +  A - Jacobian matrix
2635: -  B - optional preconditioning matrix

2637:   Options Database Keys:
2638: +    -snes_lag_preconditioner <lag>
2639: .    -snes_lag_jacobian <lag>
2640: .    -snes_test_jacobian <optional threshold> - compare the user provided Jacobian with one compute via finite differences to check for errors.  If a threshold is given, display only those entries whose difference is greater than the threshold.
2641: .    -snes_test_jacobian_view - display the user provided Jacobian, the finite difference Jacobian and the difference between them to help users detect the location of errors in the user provided Jacobian
2642: .    -snes_compare_explicit - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2643: .    -snes_compare_explicit_draw  - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2644: .    -snes_compare_explicit_contour  - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2645: .    -snes_compare_operator  - Make the comparison options above use the operator instead of the preconditioning matrix
2646: .    -snes_compare_coloring - Compute the finite difference Jacobian using coloring and display norms of difference
2647: .    -snes_compare_coloring_display - Compute the finite differece Jacobian using coloring and display verbose differences
2648: .    -snes_compare_coloring_threshold - Display only those matrix entries that differ by more than a given threshold
2649: .    -snes_compare_coloring_threshold_atol - Absolute tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2650: .    -snes_compare_coloring_threshold_rtol - Relative tolerance for difference in matrix entries to be displayed by -snes_compare_coloring_threshold
2651: .    -snes_compare_coloring_draw - Compute the finite differece Jacobian using coloring and draw differences
2652: -    -snes_compare_coloring_draw_contour - Compute the finite differece Jacobian using coloring and show contours of matrices and differences


2655:    Notes:
2656:    Most users should not need to explicitly call this routine, as it
2657:    is used internally within the nonlinear solvers.

2659:    Developer Notes:
2660:     This has duplicative ways of checking the accuracy of the user provided Jacobian (see the options above). This is for historical reasons, the routine SNESTestJacobian() use to used
2661:       for with the SNESType of test that has been removed.

2663:    Level: developer

2665: .seealso:  SNESSetJacobian(), KSPSetOperators(), MatStructure, SNESSetLagPreconditioner(), SNESSetLagJacobian()
2666: @*/
2667: PetscErrorCode  SNESComputeJacobian(SNES snes,Vec X,Mat A,Mat B)
2668: {
2670:   PetscBool      flag;
2671:   DM             dm;
2672:   DMSNES         sdm;
2673:   KSP            ksp;

2679:   VecValidValues(X,2,PETSC_TRUE);
2680:   SNESGetDM(snes,&dm);
2681:   DMGetDMSNES(dm,&sdm);

2683:   if (!sdm->ops->computejacobian) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_USER,"Must call SNESSetJacobian(), DMSNESSetJacobian(), DMDASNESSetJacobianLocal(), etc");

2685:   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix free */

2687:   if (snes->lagjacobian == -2) {
2688:     snes->lagjacobian = -1;

2690:     PetscInfo(snes,"Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n");
2691:   } else if (snes->lagjacobian == -1) {
2692:     PetscInfo(snes,"Reusing Jacobian/preconditioner because lag is -1\n");
2693:     PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);
2694:     if (flag) {
2695:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
2696:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
2697:     }
2698:     return(0);
2699:   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2700:     PetscInfo2(snes,"Reusing Jacobian/preconditioner because lag is %D and SNES iteration is %D\n",snes->lagjacobian,snes->iter);
2701:     PetscObjectTypeCompare((PetscObject)A,MATMFFD,&flag);
2702:     if (flag) {
2703:       MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
2704:       MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
2705:     }
2706:     return(0);
2707:   }
2708:   if (snes->npc && snes->npcside== PC_LEFT) {
2709:     MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
2710:     MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
2711:     return(0);
2712:   }

2714:   PetscLogEventBegin(SNES_JacobianEval,snes,X,A,B);
2715:   VecLockReadPush(X);
2716:   PetscStackPush("SNES user Jacobian function");
2717:   (*sdm->ops->computejacobian)(snes,X,A,B,sdm->jacobianctx);
2718:   PetscStackPop;
2719:   VecLockReadPop(X);
2720:   PetscLogEventEnd(SNES_JacobianEval,snes,X,A,B);

2722:   /* attach latest linearization point to the preconditioning matrix */
2723:   PetscObjectCompose((PetscObject)B,"__SNES_latest_X",(PetscObject)X);

2725:   /* the next line ensures that snes->ksp exists */
2726:   SNESGetKSP(snes,&ksp);
2727:   if (snes->lagpreconditioner == -2) {
2728:     PetscInfo(snes,"Rebuilding preconditioner exactly once since lag is -2\n");
2729:     KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);
2730:     snes->lagpreconditioner = -1;
2731:   } else if (snes->lagpreconditioner == -1) {
2732:     PetscInfo(snes,"Reusing preconditioner because lag is -1\n");
2733:     KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);
2734:   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2735:     PetscInfo2(snes,"Reusing preconditioner because lag is %D and SNES iteration is %D\n",snes->lagpreconditioner,snes->iter);
2736:     KSPSetReusePreconditioner(snes->ksp,PETSC_TRUE);
2737:   } else {
2738:     PetscInfo(snes,"Rebuilding preconditioner\n");
2739:     KSPSetReusePreconditioner(snes->ksp,PETSC_FALSE);
2740:   }

2742:   SNESTestJacobian(snes);
2743:   /* make sure user returned a correct Jacobian and preconditioner */
2746:   {
2747:     PetscBool flag = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_operator = PETSC_FALSE;
2748:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit",NULL,NULL,&flag);
2749:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit_draw",NULL,NULL,&flag_draw);
2750:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_explicit_draw_contour",NULL,NULL,&flag_contour);
2751:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject) snes)->options,((PetscObject)snes)->prefix,"-snes_compare_operator",NULL,NULL,&flag_operator);
2752:     if (flag || flag_draw || flag_contour) {
2753:       Mat          Bexp_mine = NULL,Bexp,FDexp;
2754:       PetscViewer  vdraw,vstdout;
2755:       PetscBool    flg;
2756:       if (flag_operator) {
2757:         MatComputeOperator(A,MATAIJ,&Bexp_mine);
2758:         Bexp = Bexp_mine;
2759:       } else {
2760:         /* See if the preconditioning matrix can be viewed and added directly */
2761:         PetscObjectBaseTypeCompareAny((PetscObject)B,&flg,MATSEQAIJ,MATMPIAIJ,MATSEQDENSE,MATMPIDENSE,MATSEQBAIJ,MATMPIBAIJ,MATSEQSBAIJ,MATMPIBAIJ,"");
2762:         if (flg) Bexp = B;
2763:         else {
2764:           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2765:           MatComputeOperator(B,MATAIJ,&Bexp_mine);
2766:           Bexp = Bexp_mine;
2767:         }
2768:       }
2769:       MatConvert(Bexp,MATSAME,MAT_INITIAL_MATRIX,&FDexp);
2770:       SNESComputeJacobianDefault(snes,X,FDexp,FDexp,NULL);
2771:       PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);
2772:       if (flag_draw || flag_contour) {
2773:         PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),NULL,"Explicit Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);
2774:         if (flag_contour) {PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);}
2775:       } else vdraw = NULL;
2776:       PetscViewerASCIIPrintf(vstdout,"Explicit %s\n",flag_operator ? "Jacobian" : "preconditioning Jacobian");
2777:       if (flag) {MatView(Bexp,vstdout);}
2778:       if (vdraw) {MatView(Bexp,vdraw);}
2779:       PetscViewerASCIIPrintf(vstdout,"Finite difference Jacobian\n");
2780:       if (flag) {MatView(FDexp,vstdout);}
2781:       if (vdraw) {MatView(FDexp,vdraw);}
2782:       MatAYPX(FDexp,-1.0,Bexp,SAME_NONZERO_PATTERN);
2783:       PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian\n");
2784:       if (flag) {MatView(FDexp,vstdout);}
2785:       if (vdraw) {              /* Always use contour for the difference */
2786:         PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
2787:         MatView(FDexp,vdraw);
2788:         PetscViewerPopFormat(vdraw);
2789:       }
2790:       if (flag_contour) {PetscViewerPopFormat(vdraw);}
2791:       PetscViewerDestroy(&vdraw);
2792:       MatDestroy(&Bexp_mine);
2793:       MatDestroy(&FDexp);
2794:     }
2795:   }
2796:   {
2797:     PetscBool flag = PETSC_FALSE,flag_display = PETSC_FALSE,flag_draw = PETSC_FALSE,flag_contour = PETSC_FALSE,flag_threshold = PETSC_FALSE;
2798:     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON,threshold_rtol = 10*PETSC_SQRT_MACHINE_EPSILON;
2799:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring",NULL,NULL,&flag);
2800:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_display",NULL,NULL,&flag_display);
2801:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_draw",NULL,NULL,&flag_draw);
2802:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_draw_contour",NULL,NULL,&flag_contour);
2803:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold",NULL,NULL,&flag_threshold);
2804:     if (flag_threshold) {
2805:       PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_rtol",&threshold_rtol,NULL);
2806:       PetscOptionsGetReal(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_compare_coloring_threshold_atol",&threshold_atol,NULL);
2807:     }
2808:     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2809:       Mat            Bfd;
2810:       PetscViewer    vdraw,vstdout;
2811:       MatColoring    coloring;
2812:       ISColoring     iscoloring;
2813:       MatFDColoring  matfdcoloring;
2814:       PetscErrorCode (*func)(SNES,Vec,Vec,void*);
2815:       void           *funcctx;
2816:       PetscReal      norm1,norm2,normmax;

2818:       MatDuplicate(B,MAT_DO_NOT_COPY_VALUES,&Bfd);
2819:       MatColoringCreate(Bfd,&coloring);
2820:       MatColoringSetType(coloring,MATCOLORINGSL);
2821:       MatColoringSetFromOptions(coloring);
2822:       MatColoringApply(coloring,&iscoloring);
2823:       MatColoringDestroy(&coloring);
2824:       MatFDColoringCreate(Bfd,iscoloring,&matfdcoloring);
2825:       MatFDColoringSetFromOptions(matfdcoloring);
2826:       MatFDColoringSetUp(Bfd,iscoloring,matfdcoloring);
2827:       ISColoringDestroy(&iscoloring);

2829:       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2830:       SNESGetFunction(snes,NULL,&func,&funcctx);
2831:       MatFDColoringSetFunction(matfdcoloring,(PetscErrorCode (*)(void))func,funcctx);
2832:       PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring,((PetscObject)snes)->prefix);
2833:       PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring,"coloring_");
2834:       MatFDColoringSetFromOptions(matfdcoloring);
2835:       MatFDColoringApply(Bfd,matfdcoloring,X,snes);
2836:       MatFDColoringDestroy(&matfdcoloring);

2838:       PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes),&vstdout);
2839:       if (flag_draw || flag_contour) {
2840:         PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes),NULL,"Colored Jacobians",PETSC_DECIDE,PETSC_DECIDE,300,300,&vdraw);
2841:         if (flag_contour) {PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);}
2842:       } else vdraw = NULL;
2843:       PetscViewerASCIIPrintf(vstdout,"Explicit preconditioning Jacobian\n");
2844:       if (flag_display) {MatView(B,vstdout);}
2845:       if (vdraw) {MatView(B,vdraw);}
2846:       PetscViewerASCIIPrintf(vstdout,"Colored Finite difference Jacobian\n");
2847:       if (flag_display) {MatView(Bfd,vstdout);}
2848:       if (vdraw) {MatView(Bfd,vdraw);}
2849:       MatAYPX(Bfd,-1.0,B,SAME_NONZERO_PATTERN);
2850:       MatNorm(Bfd,NORM_1,&norm1);
2851:       MatNorm(Bfd,NORM_FROBENIUS,&norm2);
2852:       MatNorm(Bfd,NORM_MAX,&normmax);
2853:       PetscViewerASCIIPrintf(vstdout,"User-provided matrix minus finite difference Jacobian, norm1=%g normFrob=%g normmax=%g\n",(double)norm1,(double)norm2,(double)normmax);
2854:       if (flag_display) {MatView(Bfd,vstdout);}
2855:       if (vdraw) {              /* Always use contour for the difference */
2856:         PetscViewerPushFormat(vdraw,PETSC_VIEWER_DRAW_CONTOUR);
2857:         MatView(Bfd,vdraw);
2858:         PetscViewerPopFormat(vdraw);
2859:       }
2860:       if (flag_contour) {PetscViewerPopFormat(vdraw);}

2862:       if (flag_threshold) {
2863:         PetscInt bs,rstart,rend,i;
2864:         MatGetBlockSize(B,&bs);
2865:         MatGetOwnershipRange(B,&rstart,&rend);
2866:         for (i=rstart; i<rend; i++) {
2867:           const PetscScalar *ba,*ca;
2868:           const PetscInt    *bj,*cj;
2869:           PetscInt          bn,cn,j,maxentrycol = -1,maxdiffcol = -1,maxrdiffcol = -1;
2870:           PetscReal         maxentry = 0,maxdiff = 0,maxrdiff = 0;
2871:           MatGetRow(B,i,&bn,&bj,&ba);
2872:           MatGetRow(Bfd,i,&cn,&cj,&ca);
2873:           if (bn != cn) SETERRQ(((PetscObject)A)->comm,PETSC_ERR_PLIB,"Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2874:           for (j=0; j<bn; j++) {
2875:             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2876:             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2877:               maxentrycol = bj[j];
2878:               maxentry    = PetscRealPart(ba[j]);
2879:             }
2880:             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2881:               maxdiffcol = bj[j];
2882:               maxdiff    = PetscRealPart(ca[j]);
2883:             }
2884:             if (rdiff > maxrdiff) {
2885:               maxrdiffcol = bj[j];
2886:               maxrdiff    = rdiff;
2887:             }
2888:           }
2889:           if (maxrdiff > 1) {
2890:             PetscViewerASCIIPrintf(vstdout,"row %D (maxentry=%g at %D, maxdiff=%g at %D, maxrdiff=%g at %D):",i,(double)maxentry,maxentrycol,(double)maxdiff,maxdiffcol,(double)maxrdiff,maxrdiffcol);
2891:             for (j=0; j<bn; j++) {
2892:               PetscReal rdiff;
2893:               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol*PetscAbsScalar(ba[j]));
2894:               if (rdiff > 1) {
2895:                 PetscViewerASCIIPrintf(vstdout," (%D,%g:%g)",bj[j],(double)PetscRealPart(ba[j]),(double)PetscRealPart(ca[j]));
2896:               }
2897:             }
2898:             PetscViewerASCIIPrintf(vstdout,"\n",i,maxentry,maxdiff,maxrdiff);
2899:           }
2900:           MatRestoreRow(B,i,&bn,&bj,&ba);
2901:           MatRestoreRow(Bfd,i,&cn,&cj,&ca);
2902:         }
2903:       }
2904:       PetscViewerDestroy(&vdraw);
2905:       MatDestroy(&Bfd);
2906:     }
2907:   }
2908:   return(0);
2909: }

2911: /*MC
2912:     SNESJacobianFunction - Function used to convey the nonlinear Jacobian of the function to be solved by SNES

2914:      Synopsis:
2915:      #include "petscsnes.h"
2916:      PetscErrorCode SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);

2918:      Collective on snes

2920:     Input Parameters:
2921: +  x - input vector, the Jacobian is to be computed at this value
2922: -  ctx - [optional] user-defined Jacobian context

2924:     Output Parameters:
2925: +  Amat - the matrix that defines the (approximate) Jacobian
2926: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

2928:    Level: intermediate

2930: .seealso:   SNESSetFunction(), SNESGetFunction(), SNESSetJacobian(), SNESGetJacobian()
2931: M*/

2933: /*@C
2934:    SNESSetJacobian - Sets the function to compute Jacobian as well as the
2935:    location to store the matrix.

2937:    Logically Collective on SNES

2939:    Input Parameters:
2940: +  snes - the SNES context
2941: .  Amat - the matrix that defines the (approximate) Jacobian
2942: .  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.
2943: .  J - Jacobian evaluation routine (if NULL then SNES retains any previously set value), see SNESJacobianFunction for details
2944: -  ctx - [optional] user-defined context for private data for the
2945:          Jacobian evaluation routine (may be NULL) (if NULL then SNES retains any previously set value)

2947:    Notes:
2948:    If the Amat matrix and Pmat matrix are different you must call MatAssemblyBegin/End() on
2949:    each matrix.

2951:    If you know the operator Amat has a null space you can use MatSetNullSpace() and MatSetTransposeNullSpace() to supply the null
2952:    space to Amat and the KSP solvers will automatically use that null space as needed during the solution process.

2954:    If using SNESComputeJacobianDefaultColor() to assemble a Jacobian, the ctx argument
2955:    must be a MatFDColoring.

2957:    Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2958:    example is to use the "Picard linearization" which only differentiates through the highest order parts of each term.

2960:    Level: beginner

2962: .seealso: KSPSetOperators(), SNESSetFunction(), MatMFFDComputeJacobian(), SNESComputeJacobianDefaultColor(), MatStructure, J,
2963:           SNESSetPicard(), SNESJacobianFunction
2964: @*/
2965: PetscErrorCode  SNESSetJacobian(SNES snes,Mat Amat,Mat Pmat,PetscErrorCode (*J)(SNES,Vec,Mat,Mat,void*),void *ctx)
2966: {
2968:   DM             dm;

2976:   SNESGetDM(snes,&dm);
2977:   DMSNESSetJacobian(dm,J,ctx);
2978:   if (Amat) {
2979:     PetscObjectReference((PetscObject)Amat);
2980:     MatDestroy(&snes->jacobian);

2982:     snes->jacobian = Amat;
2983:   }
2984:   if (Pmat) {
2985:     PetscObjectReference((PetscObject)Pmat);
2986:     MatDestroy(&snes->jacobian_pre);

2988:     snes->jacobian_pre = Pmat;
2989:   }
2990:   return(0);
2991: }

2993: /*@C
2994:    SNESGetJacobian - Returns the Jacobian matrix and optionally the user
2995:    provided context for evaluating the Jacobian.

2997:    Not Collective, but Mat object will be parallel if SNES object is

2999:    Input Parameter:
3000: .  snes - the nonlinear solver context

3002:    Output Parameters:
3003: +  Amat - location to stash (approximate) Jacobian matrix (or NULL)
3004: .  Pmat - location to stash matrix used to compute the preconditioner (or NULL)
3005: .  J - location to put Jacobian function (or NULL), see SNESJacobianFunction for details on its calling sequence
3006: -  ctx - location to stash Jacobian ctx (or NULL)

3008:    Level: advanced

3010: .seealso: SNESSetJacobian(), SNESComputeJacobian(), SNESJacobianFunction, SNESGetFunction()
3011: @*/
3012: PetscErrorCode SNESGetJacobian(SNES snes,Mat *Amat,Mat *Pmat,PetscErrorCode (**J)(SNES,Vec,Mat,Mat,void*),void **ctx)
3013: {
3015:   DM             dm;
3016:   DMSNES         sdm;

3020:   if (Amat) *Amat = snes->jacobian;
3021:   if (Pmat) *Pmat = snes->jacobian_pre;
3022:   SNESGetDM(snes,&dm);
3023:   DMGetDMSNES(dm,&sdm);
3024:   if (J) *J = sdm->ops->computejacobian;
3025:   if (ctx) *ctx = sdm->jacobianctx;
3026:   return(0);
3027: }

3029: static PetscErrorCode SNESSetDefaultComputeJacobian(SNES snes)
3030: {
3032:   DM             dm;
3033:   DMSNES         sdm;

3036:   SNESGetDM(snes,&dm);
3037:   DMGetDMSNES(dm,&sdm);
3038:   if (!sdm->ops->computejacobian && snes->jacobian_pre) {
3039:     DM        dm;
3040:     PetscBool isdense,ismf;

3042:     SNESGetDM(snes,&dm);
3043:     PetscObjectTypeCompareAny((PetscObject)snes->jacobian_pre,&isdense,MATSEQDENSE,MATMPIDENSE,MATDENSE,NULL);
3044:     PetscObjectTypeCompareAny((PetscObject)snes->jacobian_pre,&ismf,MATMFFD,MATSHELL,NULL);
3045:     if (isdense) {
3046:       DMSNESSetJacobian(dm,SNESComputeJacobianDefault,NULL);
3047:     } else if (!ismf) {
3048:       DMSNESSetJacobian(dm,SNESComputeJacobianDefaultColor,NULL);
3049:     }
3050:   }
3051:   return(0);
3052: }

3054: /*@
3055:    SNESSetUp - Sets up the internal data structures for the later use
3056:    of a nonlinear solver.

3058:    Collective on SNES

3060:    Input Parameters:
3061: .  snes - the SNES context

3063:    Notes:
3064:    For basic use of the SNES solvers the user need not explicitly call
3065:    SNESSetUp(), since these actions will automatically occur during
3066:    the call to SNESSolve().  However, if one wishes to control this
3067:    phase separately, SNESSetUp() should be called after SNESCreate()
3068:    and optional routines of the form SNESSetXXX(), but before SNESSolve().

3070:    Level: advanced

3072: .seealso: SNESCreate(), SNESSolve(), SNESDestroy()
3073: @*/
3074: PetscErrorCode  SNESSetUp(SNES snes)
3075: {
3077:   DM             dm;
3078:   DMSNES         sdm;
3079:   SNESLineSearch linesearch, pclinesearch;
3080:   void           *lsprectx,*lspostctx;
3081:   PetscErrorCode (*precheck)(SNESLineSearch,Vec,Vec,PetscBool*,void*);
3082:   PetscErrorCode (*postcheck)(SNESLineSearch,Vec,Vec,Vec,PetscBool*,PetscBool*,void*);
3083:   PetscErrorCode (*func)(SNES,Vec,Vec,void*);
3084:   Vec            f,fpc;
3085:   void           *funcctx;
3086:   PetscErrorCode (*jac)(SNES,Vec,Mat,Mat,void*);
3087:   void           *jacctx,*appctx;
3088:   Mat            j,jpre;

3092:   if (snes->setupcalled) return(0);
3093:   PetscLogEventBegin(SNES_Setup,snes,0,0,0);

3095:   if (!((PetscObject)snes)->type_name) {
3096:     SNESSetType(snes,SNESNEWTONLS);
3097:   }

3099:   SNESGetFunction(snes,&snes->vec_func,NULL,NULL);

3101:   SNESGetDM(snes,&dm);
3102:   DMGetDMSNES(dm,&sdm);
3103:   if (!sdm->ops->computefunction) SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_ARG_WRONGSTATE,"Function never provided to SNES object");
3104:   SNESSetDefaultComputeJacobian(snes);

3106:   if (!snes->vec_func) {
3107:     DMCreateGlobalVector(dm,&snes->vec_func);
3108:   }

3110:   if (!snes->ksp) {
3111:     SNESGetKSP(snes, &snes->ksp);
3112:   }

3114:   if (snes->linesearch) {
3115:     SNESGetLineSearch(snes, &snes->linesearch);
3116:     SNESLineSearchSetFunction(snes->linesearch,SNESComputeFunction);
3117:   }

3119:   if (snes->npc && (snes->npcside== PC_LEFT)) {
3120:     snes->mf          = PETSC_TRUE;
3121:     snes->mf_operator = PETSC_FALSE;
3122:   }

3124:   if (snes->npc) {
3125:     /* copy the DM over */
3126:     SNESGetDM(snes,&dm);
3127:     SNESSetDM(snes->npc,dm);

3129:     SNESGetFunction(snes,&f,&func,&funcctx);
3130:     VecDuplicate(f,&fpc);
3131:     SNESSetFunction(snes->npc,fpc,func,funcctx);
3132:     SNESGetJacobian(snes,&j,&jpre,&jac,&jacctx);
3133:     SNESSetJacobian(snes->npc,j,jpre,jac,jacctx);
3134:     SNESGetApplicationContext(snes,&appctx);
3135:     SNESSetApplicationContext(snes->npc,appctx);
3136:     VecDestroy(&fpc);

3138:     /* copy the function pointers over */
3139:     PetscObjectCopyFortranFunctionPointers((PetscObject)snes,(PetscObject)snes->npc);

3141:     /* default to 1 iteration */
3142:     SNESSetTolerances(snes->npc,0.0,0.0,0.0,1,snes->npc->max_funcs);
3143:     if (snes->npcside==PC_RIGHT) {
3144:       SNESSetNormSchedule(snes->npc,SNES_NORM_FINAL_ONLY);
3145:     } else {
3146:       SNESSetNormSchedule(snes->npc,SNES_NORM_NONE);
3147:     }
3148:     SNESSetFromOptions(snes->npc);

3150:     /* copy the line search context over */
3151:     if (snes->linesearch && snes->npc->linesearch) {
3152:       SNESGetLineSearch(snes,&linesearch);
3153:       SNESGetLineSearch(snes->npc,&pclinesearch);
3154:       SNESLineSearchGetPreCheck(linesearch,&precheck,&lsprectx);
3155:       SNESLineSearchGetPostCheck(linesearch,&postcheck,&lspostctx);
3156:       SNESLineSearchSetPreCheck(pclinesearch,precheck,lsprectx);
3157:       SNESLineSearchSetPostCheck(pclinesearch,postcheck,lspostctx);
3158:       PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch);
3159:     }
3160:   }
3161:   if (snes->mf) {
3162:     SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version);
3163:   }
3164:   if (snes->ops->usercompute && !snes->user) {
3165:     (*snes->ops->usercompute)(snes,(void**)&snes->user);
3166:   }

3168:   snes->jac_iter = 0;
3169:   snes->pre_iter = 0;

3171:   if (snes->ops->setup) {
3172:     (*snes->ops->setup)(snes);
3173:   }

3175:   SNESSetDefaultComputeJacobian(snes);

3177:   if (snes->npc && (snes->npcside== PC_LEFT)) {
3178:     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
3179:       if (snes->linesearch){
3180:         SNESGetLineSearch(snes,&linesearch);
3181:         SNESLineSearchSetFunction(linesearch,SNESComputeFunctionDefaultNPC);
3182:       }
3183:     }
3184:   }
3185:   PetscLogEventEnd(SNES_Setup,snes,0,0,0);
3186:   snes->setupcalled = PETSC_TRUE;
3187:   return(0);
3188: }

3190: /*@
3191:    SNESReset - Resets a SNES context to the snessetupcalled = 0 state and removes any allocated Vecs and Mats

3193:    Collective on SNES

3195:    Input Parameter:
3196: .  snes - iterative context obtained from SNESCreate()

3198:    Level: intermediate

3200:    Notes:
3201:     Also calls the application context destroy routine set with SNESSetComputeApplicationContext()

3203: .seealso: SNESCreate(), SNESSetUp(), SNESSolve()
3204: @*/
3205: PetscErrorCode  SNESReset(SNES snes)
3206: {

3211:   if (snes->ops->userdestroy && snes->user) {
3212:     (*snes->ops->userdestroy)((void**)&snes->user);
3213:     snes->user = NULL;
3214:   }
3215:   if (snes->npc) {
3216:     SNESReset(snes->npc);
3217:   }

3219:   if (snes->ops->reset) {
3220:     (*snes->ops->reset)(snes);
3221:   }
3222:   if (snes->ksp) {
3223:     KSPReset(snes->ksp);
3224:   }

3226:   if (snes->linesearch) {
3227:     SNESLineSearchReset(snes->linesearch);
3228:   }

3230:   VecDestroy(&snes->vec_rhs);
3231:   VecDestroy(&snes->vec_sol);
3232:   VecDestroy(&snes->vec_sol_update);
3233:   VecDestroy(&snes->vec_func);
3234:   MatDestroy(&snes->jacobian);
3235:   MatDestroy(&snes->jacobian_pre);
3236:   VecDestroyVecs(snes->nwork,&snes->work);
3237:   VecDestroyVecs(snes->nvwork,&snes->vwork);

3239:   snes->alwayscomputesfinalresidual = PETSC_FALSE;

3241:   snes->nwork       = snes->nvwork = 0;
3242:   snes->setupcalled = PETSC_FALSE;
3243:   return(0);
3244: }

3246: /*@
3247:    SNESDestroy - Destroys the nonlinear solver context that was created
3248:    with SNESCreate().

3250:    Collective on SNES

3252:    Input Parameter:
3253: .  snes - the SNES context

3255:    Level: beginner

3257: .seealso: SNESCreate(), SNESSolve()
3258: @*/
3259: PetscErrorCode  SNESDestroy(SNES *snes)
3260: {

3264:   if (!*snes) return(0);
3266:   if (--((PetscObject)(*snes))->refct > 0) {*snes = NULL; return(0);}

3268:   SNESReset((*snes));
3269:   SNESDestroy(&(*snes)->npc);

3271:   /* if memory was published with SAWs then destroy it */
3272:   PetscObjectSAWsViewOff((PetscObject)*snes);
3273:   if ((*snes)->ops->destroy) {(*((*snes))->ops->destroy)((*snes));}

3275:   if ((*snes)->dm) {DMCoarsenHookRemove((*snes)->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,*snes);}
3276:   DMDestroy(&(*snes)->dm);
3277:   KSPDestroy(&(*snes)->ksp);
3278:   SNESLineSearchDestroy(&(*snes)->linesearch);

3280:   PetscFree((*snes)->kspconvctx);
3281:   if ((*snes)->ops->convergeddestroy) {
3282:     (*(*snes)->ops->convergeddestroy)((*snes)->cnvP);
3283:   }
3284:   if ((*snes)->conv_hist_alloc) {
3285:     PetscFree2((*snes)->conv_hist,(*snes)->conv_hist_its);
3286:   }
3287:   SNESMonitorCancel((*snes));
3288:   PetscHeaderDestroy(snes);
3289:   return(0);
3290: }

3292: /* ----------- Routines to set solver parameters ---------- */

3294: /*@
3295:    SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.

3297:    Logically Collective on SNES

3299:    Input Parameters:
3300: +  snes - the SNES context
3301: -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3302:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

3304:    Options Database Keys:
3305: +    -snes_lag_jacobian_persists <true,false> - sets the persistence
3306: .    -snes_lag_jacobian <-2,1,2,...> - sets the lag
3307: .    -snes_lag_preconditioner_persists <true,false> - sets the persistence
3308: -    -snes_lag_preconditioner <-2,1,2,...> - sets the lag

3310:    Notes:
3311:    The default is 1
3312:    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1 or SNESSetLagPreconditionerPersists() was called
3313:    If  -1 is used before the very first nonlinear solve the preconditioner is still built because there is no previous preconditioner to use

3315:    Level: intermediate

3317: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESSetLagPreconditionerPersists(),
3318:           SNESSetLagJacobianPersists()

3320: @*/
3321: PetscErrorCode  SNESSetLagPreconditioner(SNES snes,PetscInt lag)
3322: {
3325:   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
3326:   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
3328:   snes->lagpreconditioner = lag;
3329:   return(0);
3330: }

3332: /*@
3333:    SNESSetGridSequence - sets the number of steps of grid sequencing that SNES does

3335:    Logically Collective on SNES

3337:    Input Parameters:
3338: +  snes - the SNES context
3339: -  steps - the number of refinements to do, defaults to 0

3341:    Options Database Keys:
3342: .    -snes_grid_sequence <steps>

3344:    Level: intermediate

3346:    Notes:
3347:    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.

3349: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetGridSequence()

3351: @*/
3352: PetscErrorCode  SNESSetGridSequence(SNES snes,PetscInt steps)
3353: {
3357:   snes->gridsequence = steps;
3358:   return(0);
3359: }

3361: /*@
3362:    SNESGetGridSequence - gets the number of steps of grid sequencing that SNES does

3364:    Logically Collective on SNES

3366:    Input Parameter:
3367: .  snes - the SNES context

3369:    Output Parameter:
3370: .  steps - the number of refinements to do, defaults to 0

3372:    Options Database Keys:
3373: .    -snes_grid_sequence <steps>

3375:    Level: intermediate

3377:    Notes:
3378:    Use SNESGetSolution() to extract the fine grid solution after grid sequencing.

3380: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESSetGridSequence()

3382: @*/
3383: PetscErrorCode  SNESGetGridSequence(SNES snes,PetscInt *steps)
3384: {
3387:   *steps = snes->gridsequence;
3388:   return(0);
3389: }

3391: /*@
3392:    SNESGetLagPreconditioner - Indicates how often the preconditioner is rebuilt

3394:    Not Collective

3396:    Input Parameter:
3397: .  snes - the SNES context

3399:    Output Parameter:
3400: .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3401:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

3403:    Options Database Keys:
3404: +    -snes_lag_jacobian_persists <true,false> - sets the persistence
3405: .    -snes_lag_jacobian <-2,1,2,...> - sets the lag
3406: .    -snes_lag_preconditioner_persists <true,false> - sets the persistence
3407: -    -snes_lag_preconditioner <-2,1,2,...> - sets the lag

3409:    Notes:
3410:    The default is 1
3411:    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1

3413:    Level: intermediate

3415: .seealso: SNESSetTrustRegionTolerance(), SNESSetLagPreconditioner(), SNESSetLagJacobianPersists(), SNESSetLagPreconditionerPersists()

3417: @*/
3418: PetscErrorCode  SNESGetLagPreconditioner(SNES snes,PetscInt *lag)
3419: {
3422:   *lag = snes->lagpreconditioner;
3423:   return(0);
3424: }

3426: /*@
3427:    SNESSetLagJacobian - Determines when the Jacobian is rebuilt in the nonlinear solve. See SNESSetLagPreconditioner() for determining how
3428:      often the preconditioner is rebuilt.

3430:    Logically Collective on SNES

3432:    Input Parameters:
3433: +  snes - the SNES context
3434: -  lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3435:          the Jacobian is built etc. -2 means rebuild at next chance but then never again

3437:    Options Database Keys:
3438: +    -snes_lag_jacobian_persists <true,false> - sets the persistence
3439: .    -snes_lag_jacobian <-2,1,2,...> - sets the lag
3440: .    -snes_lag_preconditioner_persists <true,false> - sets the persistence
3441: -    -snes_lag_preconditioner <-2,1,2,...> - sets the lag.

3443:    Notes:
3444:    The default is 1
3445:    The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1
3446:    If  -1 is used before the very first nonlinear solve the CODE WILL FAIL! because no Jacobian is used, use -2 to indicate you want it recomputed
3447:    at the next Newton step but never again (unless it is reset to another value)

3449:    Level: intermediate

3451: .seealso: SNESSetTrustRegionTolerance(), SNESGetLagPreconditioner(), SNESSetLagPreconditioner(), SNESGetLagJacobianPersists(), SNESSetLagPreconditionerPersists()

3453: @*/
3454: PetscErrorCode  SNESSetLagJacobian(SNES snes,PetscInt lag)
3455: {
3458:   if (lag < -2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag must be -2, -1, 1 or greater");
3459:   if (!lag) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Lag cannot be 0");
3461:   snes->lagjacobian = lag;
3462:   return(0);
3463: }

3465: /*@
3466:    SNESGetLagJacobian - Indicates how often the Jacobian is rebuilt. See SNESGetLagPreconditioner() to determine when the preconditioner is rebuilt

3468:    Not Collective

3470:    Input Parameter:
3471: .  snes - the SNES context

3473:    Output Parameter:
3474: .   lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3475:          the Jacobian is built etc.

3477:    Notes:
3478:    The default is 1
3479:    The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1 or SNESSetLagJacobianPersists() was called.

3481:    Level: intermediate

3483: .seealso: SNESSetTrustRegionTolerance(), SNESSetLagJacobian(), SNESSetLagPreconditioner(), SNESGetLagPreconditioner(), SNESSetLagJacobianPersists(), SNESSetLagPreconditionerPersists()

3485: @*/
3486: PetscErrorCode  SNESGetLagJacobian(SNES snes,PetscInt *lag)
3487: {
3490:   *lag = snes->lagjacobian;
3491:   return(0);
3492: }

3494: /*@
3495:    SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple solves

3497:    Logically collective on SNES

3499:    Input Parameter:
3500: +  snes - the SNES context
3501: -   flg - jacobian lagging persists if true

3503:    Options Database Keys:
3504: +    -snes_lag_jacobian_persists <true,false> - sets the persistence
3505: .    -snes_lag_jacobian <-2,1,2,...> - sets the lag
3506: .    -snes_lag_preconditioner_persists <true,false> - sets the persistence
3507: -    -snes_lag_preconditioner <-2,1,2,...> - sets the lag


3510:    Notes:
3511:     This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
3512:    several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
3513:    timesteps may present huge efficiency gains.

3515:    Level: developer

3517: .seealso: SNESSetLagPreconditionerPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC(), SNESSetLagJacobianPersists()

3519: @*/
3520: PetscErrorCode  SNESSetLagJacobianPersists(SNES snes,PetscBool flg)
3521: {
3525:   snes->lagjac_persist = flg;
3526:   return(0);
3527: }

3529: /*@
3530:    SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple solves

3532:    Logically Collective on SNES

3534:    Input Parameter:
3535: +  snes - the SNES context
3536: -   flg - preconditioner lagging persists if true

3538:    Options Database Keys:
3539: +    -snes_lag_jacobian_persists <true,false> - sets the persistence
3540: .    -snes_lag_jacobian <-2,1,2,...> - sets the lag
3541: .    -snes_lag_preconditioner_persists <true,false> - sets the persistence
3542: -    -snes_lag_preconditioner <-2,1,2,...> - sets the lag

3544:    Notes:
3545:     This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
3546:    by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
3547:    several timesteps may present huge efficiency gains.

3549:    Level: developer

3551: .seealso: SNESSetLagJacobianPersists(), SNESSetLagJacobian(), SNESGetLagJacobian(), SNESGetNPC(), SNESSetLagPreconditioner()

3553: @*/
3554: PetscErrorCode  SNESSetLagPreconditionerPersists(SNES snes,PetscBool flg)
3555: {
3559:   snes->lagpre_persist = flg;
3560:   return(0);
3561: }

3563: /*@
3564:    SNESSetForceIteration - force SNESSolve() to take at least one iteration regardless of the initial residual norm

3566:    Logically Collective on SNES

3568:    Input Parameters:
3569: +  snes - the SNES context
3570: -  force - PETSC_TRUE require at least one iteration

3572:    Options Database Keys:
3573: .    -snes_force_iteration <force> - Sets forcing an iteration

3575:    Notes:
3576:    This is used sometimes with TS to prevent TS from detecting a false steady state solution

3578:    Level: intermediate

3580: .seealso: SNESSetTrustRegionTolerance(), SNESSetDivergenceTolerance()
3581: @*/
3582: PetscErrorCode  SNESSetForceIteration(SNES snes,PetscBool force)
3583: {
3586:   snes->forceiteration = force;
3587:   return(0);
3588: }

3590: /*@
3591:    SNESGetForceIteration - Whether or not to force SNESSolve() take at least one iteration regardless of the initial residual norm

3593:    Logically Collective on SNES

3595:    Input Parameters:
3596: .  snes - the SNES context

3598:    Output Parameter:
3599: .  force - PETSC_TRUE requires at least one iteration.

3601:    Level: intermediate

3603: .seealso: SNESSetForceIteration(), SNESSetTrustRegionTolerance(), SNESSetDivergenceTolerance()
3604: @*/
3605: PetscErrorCode  SNESGetForceIteration(SNES snes,PetscBool *force)
3606: {
3609:   *force = snes->forceiteration;
3610:   return(0);
3611: }

3613: /*@
3614:    SNESSetTolerances - Sets various parameters used in convergence tests.

3616:    Logically Collective on SNES

3618:    Input Parameters:
3619: +  snes - the SNES context
3620: .  abstol - absolute convergence tolerance
3621: .  rtol - relative convergence tolerance
3622: .  stol -  convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
3623: .  maxit - maximum number of iterations
3624: -  maxf - maximum number of function evaluations (-1 indicates no limit)

3626:    Options Database Keys:
3627: +    -snes_atol <abstol> - Sets abstol
3628: .    -snes_rtol <rtol> - Sets rtol
3629: .    -snes_stol <stol> - Sets stol
3630: .    -snes_max_it <maxit> - Sets maxit
3631: -    -snes_max_funcs <maxf> - Sets maxf

3633:    Notes:
3634:    The default maximum number of iterations is 50.
3635:    The default maximum number of function evaluations is 1000.

3637:    Level: intermediate

3639: .seealso: SNESSetTrustRegionTolerance(), SNESSetDivergenceTolerance(), SNESSetForceIteration()
3640: @*/
3641: PetscErrorCode  SNESSetTolerances(SNES snes,PetscReal abstol,PetscReal rtol,PetscReal stol,PetscInt maxit,PetscInt maxf)
3642: {

3651:   if (abstol != PETSC_DEFAULT) {
3652:     if (abstol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Absolute tolerance %g must be non-negative",(double)abstol);
3653:     snes->abstol = abstol;
3654:   }
3655:   if (rtol != PETSC_DEFAULT) {
3656:     if (rtol < 0.0 || 1.0 <= rtol) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Relative tolerance %g must be non-negative and less than 1.0",(double)rtol);
3657:     snes->rtol = rtol;
3658:   }
3659:   if (stol != PETSC_DEFAULT) {
3660:     if (stol < 0.0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Step tolerance %g must be non-negative",(double)stol);
3661:     snes->stol = stol;
3662:   }
3663:   if (maxit != PETSC_DEFAULT) {
3664:     if (maxit < 0) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of iterations %D must be non-negative",maxit);
3665:     snes->max_its = maxit;
3666:   }
3667:   if (maxf != PETSC_DEFAULT) {
3668:     if (maxf < -1) SETERRQ1(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_OUTOFRANGE,"Maximum number of function evaluations %D must be -1 or nonnegative",maxf);
3669:     snes->max_funcs = maxf;
3670:   }
3671:   snes->tolerancesset = PETSC_TRUE;
3672:   return(0);
3673: }

3675: /*@
3676:    SNESSetDivergenceTolerance - Sets the divergence tolerance used for the SNES divergence test.

3678:    Logically Collective on SNES

3680:    Input Parameters:
3681: +  snes - the SNES context
3682: -  divtol - the divergence tolerance. Use -1 to deactivate the test.

3684:    Options Database Keys:
3685: .    -snes_divergence_tolerance <divtol> - Sets divtol

3687:    Notes:
3688:    The default divergence tolerance is 1e4.

3690:    Level: intermediate

3692: .seealso: SNESSetTolerances(), SNESGetDivergenceTolerance
3693: @*/
3694: PetscErrorCode  SNESSetDivergenceTolerance(SNES snes,PetscReal divtol)
3695: {

3700:   if (divtol != PETSC_DEFAULT) {
3701:     snes->divtol = divtol;
3702:   }
3703:   else {
3704:     snes->divtol = 1.0e4;
3705:   }
3706:   return(0);
3707: }

3709: /*@
3710:    SNESGetTolerances - Gets various parameters used in convergence tests.

3712:    Not Collective

3714:    Input Parameters:
3715: +  snes - the SNES context
3716: .  atol - absolute convergence tolerance
3717: .  rtol - relative convergence tolerance
3718: .  stol -  convergence tolerance in terms of the norm
3719:            of the change in the solution between steps
3720: .  maxit - maximum number of iterations
3721: -  maxf - maximum number of function evaluations

3723:    Notes:
3724:    The user can specify NULL for any parameter that is not needed.

3726:    Level: intermediate

3728: .seealso: SNESSetTolerances()
3729: @*/
3730: PetscErrorCode  SNESGetTolerances(SNES snes,PetscReal *atol,PetscReal *rtol,PetscReal *stol,PetscInt *maxit,PetscInt *maxf)
3731: {
3734:   if (atol)  *atol  = snes->abstol;
3735:   if (rtol)  *rtol  = snes->rtol;
3736:   if (stol)  *stol  = snes->stol;
3737:   if (maxit) *maxit = snes->max_its;
3738:   if (maxf)  *maxf  = snes->max_funcs;
3739:   return(0);
3740: }

3742: /*@
3743:    SNESGetDivergenceTolerance - Gets divergence tolerance used in divergence test.

3745:    Not Collective

3747:    Input Parameters:
3748: +  snes - the SNES context
3749: -  divtol - divergence tolerance

3751:    Level: intermediate

3753: .seealso: SNESSetDivergenceTolerance()
3754: @*/
3755: PetscErrorCode  SNESGetDivergenceTolerance(SNES snes,PetscReal *divtol)
3756: {
3759:   if (divtol) *divtol = snes->divtol;
3760:   return(0);
3761: }

3763: /*@
3764:    SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.

3766:    Logically Collective on SNES

3768:    Input Parameters:
3769: +  snes - the SNES context
3770: -  tol - tolerance

3772:    Options Database Key:
3773: .  -snes_trtol <tol> - Sets tol

3775:    Level: intermediate

3777: .seealso: SNESSetTolerances()
3778: @*/
3779: PetscErrorCode  SNESSetTrustRegionTolerance(SNES snes,PetscReal tol)
3780: {
3784:   snes->deltatol = tol;
3785:   return(0);
3786: }

3788: /*
3789:    Duplicate the lg monitors for SNES from KSP; for some reason with
3790:    dynamic libraries things don't work under Sun4 if we just use
3791:    macros instead of functions
3792: */
3793: PetscErrorCode  SNESMonitorLGResidualNorm(SNES snes,PetscInt it,PetscReal norm,void *ctx)
3794: {

3799:   KSPMonitorLGResidualNorm((KSP)snes,it,norm,ctx);
3800:   return(0);
3801: }

3803: PetscErrorCode  SNESMonitorLGCreate(MPI_Comm comm,const char host[],const char label[],int x,int y,int m,int n,PetscDrawLG *lgctx)
3804: {

3808:   KSPMonitorLGResidualNormCreate(comm,host,label,x,y,m,n,lgctx);
3809:   return(0);
3810: }

3812: PETSC_INTERN PetscErrorCode  SNESMonitorRange_Private(SNES,PetscInt,PetscReal*);

3814: PetscErrorCode  SNESMonitorLGRange(SNES snes,PetscInt n,PetscReal rnorm,void *monctx)
3815: {
3816:   PetscDrawLG      lg;
3817:   PetscErrorCode   ierr;
3818:   PetscReal        x,y,per;
3819:   PetscViewer      v = (PetscViewer)monctx;
3820:   static PetscReal prev; /* should be in the context */
3821:   PetscDraw        draw;

3825:   PetscViewerDrawGetDrawLG(v,0,&lg);
3826:   if (!n) {PetscDrawLGReset(lg);}
3827:   PetscDrawLGGetDraw(lg,&draw);
3828:   PetscDrawSetTitle(draw,"Residual norm");
3829:   x    = (PetscReal)n;
3830:   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
3831:   else y = -15.0;
3832:   PetscDrawLGAddPoint(lg,&x,&y);
3833:   if (n < 20 || !(n % 5) || snes->reason) {
3834:     PetscDrawLGDraw(lg);
3835:     PetscDrawLGSave(lg);
3836:   }

3838:   PetscViewerDrawGetDrawLG(v,1,&lg);
3839:   if (!n) {PetscDrawLGReset(lg);}
3840:   PetscDrawLGGetDraw(lg,&draw);
3841:   PetscDrawSetTitle(draw,"% elemts > .2*max elemt");
3842:    SNESMonitorRange_Private(snes,n,&per);
3843:   x    = (PetscReal)n;
3844:   y    = 100.0*per;
3845:   PetscDrawLGAddPoint(lg,&x,&y);
3846:   if (n < 20 || !(n % 5) || snes->reason) {
3847:     PetscDrawLGDraw(lg);
3848:     PetscDrawLGSave(lg);
3849:   }

3851:   PetscViewerDrawGetDrawLG(v,2,&lg);
3852:   if (!n) {prev = rnorm;PetscDrawLGReset(lg);}
3853:   PetscDrawLGGetDraw(lg,&draw);
3854:   PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm");
3855:   x    = (PetscReal)n;
3856:   y    = (prev - rnorm)/prev;
3857:   PetscDrawLGAddPoint(lg,&x,&y);
3858:   if (n < 20 || !(n % 5) || snes->reason) {
3859:     PetscDrawLGDraw(lg);
3860:     PetscDrawLGSave(lg);
3861:   }

3863:   PetscViewerDrawGetDrawLG(v,3,&lg);
3864:   if (!n) {PetscDrawLGReset(lg);}
3865:   PetscDrawLGGetDraw(lg,&draw);
3866:   PetscDrawSetTitle(draw,"(norm -oldnorm)/oldnorm*(% > .2 max)");
3867:   x    = (PetscReal)n;
3868:   y    = (prev - rnorm)/(prev*per);
3869:   if (n > 2) { /*skip initial crazy value */
3870:     PetscDrawLGAddPoint(lg,&x,&y);
3871:   }
3872:   if (n < 20 || !(n % 5) || snes->reason) {
3873:     PetscDrawLGDraw(lg);
3874:     PetscDrawLGSave(lg);
3875:   }
3876:   prev = rnorm;
3877:   return(0);
3878: }

3880: /*@
3881:    SNESMonitor - runs the user provided monitor routines, if they exist

3883:    Collective on SNES

3885:    Input Parameters:
3886: +  snes - nonlinear solver context obtained from SNESCreate()
3887: .  iter - iteration number
3888: -  rnorm - relative norm of the residual

3890:    Notes:
3891:    This routine is called by the SNES implementations.
3892:    It does not typically need to be called by the user.

3894:    Level: developer

3896: .seealso: SNESMonitorSet()
3897: @*/
3898: PetscErrorCode  SNESMonitor(SNES snes,PetscInt iter,PetscReal rnorm)
3899: {
3901:   PetscInt       i,n = snes->numbermonitors;

3904:   VecLockReadPush(snes->vec_sol);
3905:   for (i=0; i<n; i++) {
3906:     (*snes->monitor[i])(snes,iter,rnorm,snes->monitorcontext[i]);
3907:   }
3908:   VecLockReadPop(snes->vec_sol);
3909:   return(0);
3910: }

3912: /* ------------ Routines to set performance monitoring options ----------- */

3914: /*MC
3915:     SNESMonitorFunction - functional form passed to SNESMonitorSet() to monitor convergence of nonlinear solver

3917:      Synopsis:
3918: #include <petscsnes.h>
3919: $    PetscErrorCode SNESMonitorFunction(SNES snes,PetscInt its, PetscReal norm,void *mctx)

3921:      Collective on snes

3923:     Input Parameters:
3924: +    snes - the SNES context
3925: .    its - iteration number
3926: .    norm - 2-norm function value (may be estimated)
3927: -    mctx - [optional] monitoring context

3929:    Level: advanced

3931: .seealso:   SNESMonitorSet(), SNESMonitorGet()
3932: M*/

3934: /*@C
3935:    SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3936:    iteration of the nonlinear solver to display the iteration's
3937:    progress.

3939:    Logically Collective on SNES

3941:    Input Parameters:
3942: +  snes - the SNES context
3943: .  f - the monitor function, see SNESMonitorFunction for the calling sequence
3944: .  mctx - [optional] user-defined context for private data for the
3945:           monitor routine (use NULL if no context is desired)
3946: -  monitordestroy - [optional] routine that frees monitor context
3947:           (may be NULL)

3949:    Options Database Keys:
3950: +    -snes_monitor        - sets SNESMonitorDefault()
3951: .    -snes_monitor_lg_residualnorm    - sets line graph monitor,
3952:                             uses SNESMonitorLGCreate()
3953: -    -snes_monitor_cancel - cancels all monitors that have
3954:                             been hardwired into a code by
3955:                             calls to SNESMonitorSet(), but
3956:                             does not cancel those set via
3957:                             the options database.

3959:    Notes:
3960:    Several different monitoring routines may be set by calling
3961:    SNESMonitorSet() multiple times; all will be called in the
3962:    order in which they were set.

3964:    Fortran Notes:
3965:     Only a single monitor function can be set for each SNES object

3967:    Level: intermediate

3969: .seealso: SNESMonitorDefault(), SNESMonitorCancel(), SNESMonitorFunction
3970: @*/
3971: PetscErrorCode  SNESMonitorSet(SNES snes,PetscErrorCode (*f)(SNES,PetscInt,PetscReal,void*),void *mctx,PetscErrorCode (*monitordestroy)(void**))
3972: {
3973:   PetscInt       i;
3975:   PetscBool      identical;

3979:   for (i=0; i<snes->numbermonitors;i++) {
3980:     PetscMonitorCompare((PetscErrorCode (*)(void))f,mctx,monitordestroy,(PetscErrorCode (*)(void))snes->monitor[i],snes->monitorcontext[i],snes->monitordestroy[i],&identical);
3981:     if (identical) return(0);
3982:   }
3983:   if (snes->numbermonitors >= MAXSNESMONITORS) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many monitors set");
3984:   snes->monitor[snes->numbermonitors]          = f;
3985:   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
3986:   snes->monitorcontext[snes->numbermonitors++] = (void*)mctx;
3987:   return(0);
3988: }

3990: /*@
3991:    SNESMonitorCancel - Clears all the monitor functions for a SNES object.

3993:    Logically Collective on SNES

3995:    Input Parameters:
3996: .  snes - the SNES context

3998:    Options Database Key:
3999: .  -snes_monitor_cancel - cancels all monitors that have been hardwired
4000:     into a code by calls to SNESMonitorSet(), but does not cancel those
4001:     set via the options database

4003:    Notes:
4004:    There is no way to clear one specific monitor from a SNES object.

4006:    Level: intermediate

4008: .seealso: SNESMonitorDefault(), SNESMonitorSet()
4009: @*/
4010: PetscErrorCode  SNESMonitorCancel(SNES snes)
4011: {
4013:   PetscInt       i;

4017:   for (i=0; i<snes->numbermonitors; i++) {
4018:     if (snes->monitordestroy[i]) {
4019:       (*snes->monitordestroy[i])(&snes->monitorcontext[i]);
4020:     }
4021:   }
4022:   snes->numbermonitors = 0;
4023:   return(0);
4024: }

4026: /*MC
4027:     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver

4029:      Synopsis:
4030: #include <petscsnes.h>
4031: $     PetscErrorCode SNESConvergenceTest(SNES snes,PetscInt it,PetscReal xnorm,PetscReal gnorm,PetscReal f,SNESConvergedReason *reason,void *cctx)

4033:      Collective on snes

4035:     Input Parameters:
4036: +    snes - the SNES context
4037: .    it - current iteration (0 is the first and is before any Newton step)
4038: .    xnorm - 2-norm of current iterate
4039: .    gnorm - 2-norm of current step
4040: .    f - 2-norm of function
4041: -    cctx - [optional] convergence context

4043:     Output Parameter:
4044: .    reason - reason for convergence/divergence, only needs to be set when convergence or divergence is detected

4046:    Level: intermediate

4048: .seealso:   SNESSetConvergenceTest(), SNESGetConvergenceTest()
4049: M*/

4051: /*@C
4052:    SNESSetConvergenceTest - Sets the function that is to be used
4053:    to test for convergence of the nonlinear iterative solution.

4055:    Logically Collective on SNES

4057:    Input Parameters:
4058: +  snes - the SNES context
4059: .  SNESConvergenceTestFunction - routine to test for convergence
4060: .  cctx - [optional] context for private data for the convergence routine  (may be NULL)
4061: -  destroy - [optional] destructor for the context (may be NULL; PETSC_NULL_FUNCTION in Fortran)

4063:    Level: advanced

4065: .seealso: SNESConvergedDefault(), SNESConvergedSkip(), SNESConvergenceTestFunction
4066: @*/
4067: PetscErrorCode  SNESSetConvergenceTest(SNES snes,PetscErrorCode (*SNESConvergenceTestFunction)(SNES,PetscInt,PetscReal,PetscReal,PetscReal,SNESConvergedReason*,void*),void *cctx,PetscErrorCode (*destroy)(void*))
4068: {

4073:   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
4074:   if (snes->ops->convergeddestroy) {
4075:     (*snes->ops->convergeddestroy)(snes->cnvP);
4076:   }
4077:   snes->ops->converged        = SNESConvergenceTestFunction;
4078:   snes->ops->convergeddestroy = destroy;
4079:   snes->cnvP                  = cctx;
4080:   return(0);
4081: }

4083: /*@
4084:    SNESGetConvergedReason - Gets the reason the SNES iteration was stopped.

4086:    Not Collective

4088:    Input Parameter:
4089: .  snes - the SNES context

4091:    Output Parameter:
4092: .  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
4093:             manual pages for the individual convergence tests for complete lists

4095:    Options Database:
4096: .   -snes_converged_reason - prints the reason to standard out

4098:    Level: intermediate

4100:    Notes:
4101:     Should only be called after the call the SNESSolve() is complete, if it is called earlier it returns the value SNES__CONVERGED_ITERATING.

4103: .seealso: SNESSetConvergenceTest(), SNESSetConvergedReason(), SNESConvergedReason
4104: @*/
4105: PetscErrorCode SNESGetConvergedReason(SNES snes,SNESConvergedReason *reason)
4106: {
4110:   *reason = snes->reason;
4111:   return(0);
4112: }

4114: /*@
4115:    SNESSetConvergedReason - Sets the reason the SNES iteration was stopped.

4117:    Not Collective

4119:    Input Parameters:
4120: +  snes - the SNES context
4121: -  reason - negative value indicates diverged, positive value converged, see SNESConvergedReason or the
4122:             manual pages for the individual convergence tests for complete lists

4124:    Level: intermediate

4126: .seealso: SNESGetConvergedReason(), SNESSetConvergenceTest(), SNESConvergedReason
4127: @*/
4128: PetscErrorCode SNESSetConvergedReason(SNES snes,SNESConvergedReason reason)
4129: {
4132:   snes->reason = reason;
4133:   return(0);
4134: }

4136: /*@
4137:    SNESSetConvergenceHistory - Sets the array used to hold the convergence history.

4139:    Logically Collective on SNES

4141:    Input Parameters:
4142: +  snes - iterative context obtained from SNESCreate()
4143: .  a   - array to hold history, this array will contain the function norms computed at each step
4144: .  its - integer array holds the number of linear iterations for each solve.
4145: .  na  - size of a and its
4146: -  reset - PETSC_TRUE indicates each new nonlinear solve resets the history counter to zero,
4147:            else it continues storing new values for new nonlinear solves after the old ones

4149:    Notes:
4150:    If 'a' and 'its' are NULL then space is allocated for the history. If 'na' PETSC_DECIDE or PETSC_DEFAULT then a
4151:    default array of length 10000 is allocated.

4153:    This routine is useful, e.g., when running a code for purposes
4154:    of accurate performance monitoring, when no I/O should be done
4155:    during the section of code that is being timed.

4157:    Level: intermediate

4159: .seealso: SNESGetConvergenceHistory()

4161: @*/
4162: PetscErrorCode  SNESSetConvergenceHistory(SNES snes,PetscReal a[],PetscInt its[],PetscInt na,PetscBool reset)
4163: {

4170:   if (!a) {
4171:     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
4172:     PetscCalloc2(na,&a,na,&its);
4173:     snes->conv_hist_alloc = PETSC_TRUE;
4174:   }
4175:   snes->conv_hist       = a;
4176:   snes->conv_hist_its   = its;
4177:   snes->conv_hist_max   = na;
4178:   snes->conv_hist_len   = 0;
4179:   snes->conv_hist_reset = reset;
4180:   return(0);
4181: }

4183: #if defined(PETSC_HAVE_MATLAB_ENGINE)
4184: #include <engine.h>   /* MATLAB include file */
4185: #include <mex.h>      /* MATLAB include file */

4187: PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
4188: {
4189:   mxArray   *mat;
4190:   PetscInt  i;
4191:   PetscReal *ar;

4194:   mat = mxCreateDoubleMatrix(snes->conv_hist_len,1,mxREAL);
4195:   ar  = (PetscReal*) mxGetData(mat);
4196:   for (i=0; i<snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
4197:   PetscFunctionReturn(mat);
4198: }
4199: #endif

4201: /*@C
4202:    SNESGetConvergenceHistory - Gets the array used to hold the convergence history.

4204:    Not Collective

4206:    Input Parameter:
4207: .  snes - iterative context obtained from SNESCreate()

4209:    Output Parameters:
4210: +  a   - array to hold history
4211: .  its - integer array holds the number of linear iterations (or
4212:          negative if not converged) for each solve.
4213: -  na  - size of a and its

4215:    Notes:
4216:     The calling sequence for this routine in Fortran is
4217: $   call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)

4219:    This routine is useful, e.g., when running a code for purposes
4220:    of accurate performance monitoring, when no I/O should be done
4221:    during the section of code that is being timed.

4223:    Level: intermediate

4225: .seealso: SNESSetConvergenceHistory()

4227: @*/
4228: PetscErrorCode  SNESGetConvergenceHistory(SNES snes,PetscReal *a[],PetscInt *its[],PetscInt *na)
4229: {
4232:   if (a)   *a   = snes->conv_hist;
4233:   if (its) *its = snes->conv_hist_its;
4234:   if (na)  *na  = snes->conv_hist_len;
4235:   return(0);
4236: }

4238: /*@C
4239:   SNESSetUpdate - Sets the general-purpose update function called
4240:   at the beginning of every iteration of the nonlinear solve. Specifically
4241:   it is called just before the Jacobian is "evaluated".

4243:   Logically Collective on SNES

4245:   Input Parameters:
4246: + snes - The nonlinear solver context
4247: - func - The function

4249:   Calling sequence of func:
4250: $ func (SNES snes, PetscInt step);

4252: . step - The current step of the iteration

4254:   Level: advanced

4256:   Note: This is NOT what one uses to update the ghost points before a function evaluation, that should be done at the beginning of your FormFunction()
4257:         This is not used by most users.

4259: .seealso SNESSetJacobian(), SNESSolve()
4260: @*/
4261: PetscErrorCode  SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES, PetscInt))
4262: {
4265:   snes->ops->update = func;
4266:   return(0);
4267: }

4269: /*
4270:    SNESScaleStep_Private - Scales a step so that its length is less than the
4271:    positive parameter delta.

4273:     Input Parameters:
4274: +   snes - the SNES context
4275: .   y - approximate solution of linear system
4276: .   fnorm - 2-norm of current function
4277: -   delta - trust region size

4279:     Output Parameters:
4280: +   gpnorm - predicted function norm at the new point, assuming local
4281:     linearization.  The value is zero if the step lies within the trust
4282:     region, and exceeds zero otherwise.
4283: -   ynorm - 2-norm of the step

4285:     Note:
4286:     For non-trust region methods such as SNESNEWTONLS, the parameter delta
4287:     is set to be the maximum allowable step size.

4289: */
4290: PetscErrorCode SNESScaleStep_Private(SNES snes,Vec y,PetscReal *fnorm,PetscReal *delta,PetscReal *gpnorm,PetscReal *ynorm)
4291: {
4292:   PetscReal      nrm;
4293:   PetscScalar    cnorm;


4301:   VecNorm(y,NORM_2,&nrm);
4302:   if (nrm > *delta) {
4303:     nrm     = *delta/nrm;
4304:     *gpnorm = (1.0 - nrm)*(*fnorm);
4305:     cnorm   = nrm;
4306:     VecScale(y,cnorm);
4307:     *ynorm  = *delta;
4308:   } else {
4309:     *gpnorm = 0.0;
4310:     *ynorm  = nrm;
4311:   }
4312:   return(0);
4313: }

4315: /*@C
4316:    SNESConvergedReasonView - Displays the reason a SNES solve converged or diverged to a viewer

4318:    Collective on SNES

4320:    Parameter:
4321: +  snes - iterative context obtained from SNESCreate()
4322: -  viewer - the viewer to display the reason


4325:    Options Database Keys:
4326: +  -snes_converged_reason - print reason for converged or diverged, also prints number of iterations
4327: -  -snes_converged_reason ::failed - only print reason and number of iterations when diverged

4329:   Notes:
4330:      To change the format of the output call PetscViewerPushFormat(viewer,format) before this call. Use PETSC_VIEWER_DEFAULT for the default,
4331:      use PETSC_VIEWER_FAILED to only display a reason if it fails.

4333:    Level: beginner

4335: .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault(), SNESGetConvergedReason(), SNESConvergedReasonViewFromOptions(),
4336:           PetscViewerPushFormat(), PetscViewerPopFormat()

4338: @*/
4339: PetscErrorCode  SNESConvergedReasonView(SNES snes,PetscViewer viewer)
4340: {
4341:   PetscViewerFormat format;
4342:   PetscBool         isAscii;
4343:   PetscErrorCode    ierr;

4346:   if (!viewer) viewer = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes));
4347:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isAscii);
4348:   if (isAscii) {
4349:     PetscViewerGetFormat(viewer, &format);
4350:     PetscViewerASCIIAddTab(viewer,((PetscObject)snes)->tablevel);
4351:     if (format == PETSC_VIEWER_ASCII_INFO_DETAIL) {
4352:       DM              dm;
4353:       Vec             u;
4354:       PetscDS         prob;
4355:       PetscInt        Nf, f;
4356:       PetscErrorCode (**exactSol)(PetscInt, PetscReal, const PetscReal[], PetscInt, PetscScalar[], void *);
4357:       void            **exactCtx;
4358:       PetscReal       error;

4360:       SNESGetDM(snes, &dm);
4361:       SNESGetSolution(snes, &u);
4362:       DMGetDS(dm, &prob);
4363:       PetscDSGetNumFields(prob, &Nf);
4364:       PetscMalloc2(Nf, &exactSol, Nf, &exactCtx);
4365:       for (f = 0; f < Nf; ++f) {PetscDSGetExactSolution(prob, f, &exactSol[f], &exactCtx[f]);}
4366:       DMComputeL2Diff(dm, 0.0, exactSol, exactCtx, u, &error);
4367:       PetscFree2(exactSol, exactCtx);
4368:       if (error < 1.0e-11) {PetscViewerASCIIPrintf(viewer, "L_2 Error: < 1.0e-11\n");}
4369:       else                 {PetscViewerASCIIPrintf(viewer, "L_2 Error: %g\n", error);}
4370:     }
4371:     if (snes->reason > 0 && format != PETSC_VIEWER_FAILED) {
4372:       if (((PetscObject) snes)->prefix) {
4373:         PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve converged due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);
4374:       } else {
4375:         PetscViewerASCIIPrintf(viewer,"Nonlinear solve converged due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);
4376:       }
4377:     } else if (snes->reason <= 0) {
4378:       if (((PetscObject) snes)->prefix) {
4379:         PetscViewerASCIIPrintf(viewer,"Nonlinear %s solve did not converge due to %s iterations %D\n",((PetscObject) snes)->prefix,SNESConvergedReasons[snes->reason],snes->iter);
4380:       } else {
4381:         PetscViewerASCIIPrintf(viewer,"Nonlinear solve did not converge due to %s iterations %D\n",SNESConvergedReasons[snes->reason],snes->iter);
4382:       }
4383:     }
4384:     PetscViewerASCIISubtractTab(viewer,((PetscObject)snes)->tablevel);
4385:   }
4386:   return(0);
4387: }

4389: /*@
4390:   SNESConvergedReasonViewFromOptions - Processes command line options to determine if/how a SNESReason is to be viewed.

4392:   Collective on SNES

4394:   Input Parameters:
4395: . snes   - the SNES object

4397:   Level: intermediate

4399: .seealso: SNESCreate(), SNESSetUp(), SNESDestroy(), SNESSetTolerances(), SNESConvergedDefault(), SNESGetConvergedReason(), SNESConvergedReasonView()

4401: @*/
4402: PetscErrorCode SNESConvergedReasonViewFromOptions(SNES snes)
4403: {
4404:   PetscErrorCode    ierr;
4405:   PetscViewer       viewer;
4406:   PetscBool         flg;
4407:   static PetscBool  incall = PETSC_FALSE;
4408:   PetscViewerFormat format;

4411:   if (incall) return(0);
4412:   incall = PETSC_TRUE;
4413:   PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_converged_reason",&viewer,&format,&flg);
4414:   if (flg) {
4415:     PetscViewerPushFormat(viewer,format);
4416:     SNESConvergedReasonView(snes,viewer);
4417:     PetscViewerPopFormat(viewer);
4418:     PetscViewerDestroy(&viewer);
4419:   }
4420:   incall = PETSC_FALSE;
4421:   return(0);
4422: }

4424: /*@
4425:    SNESSolve - Solves a nonlinear system F(x) = b.
4426:    Call SNESSolve() after calling SNESCreate() and optional routines of the form SNESSetXXX().

4428:    Collective on SNES

4430:    Input Parameters:
4431: +  snes - the SNES context
4432: .  b - the constant part of the equation F(x) = b, or NULL to use zero.
4433: -  x - the solution vector.

4435:    Notes:
4436:    The user should initialize the vector,x, with the initial guess
4437:    for the nonlinear solve prior to calling SNESSolve.  In particular,
4438:    to employ an initial guess of zero, the user should explicitly set
4439:    this vector to zero by calling VecSet().

4441:    Level: beginner

4443: .seealso: SNESCreate(), SNESDestroy(), SNESSetFunction(), SNESSetJacobian(), SNESSetGridSequence(), SNESGetSolution()
4444: @*/
4445: PetscErrorCode  SNESSolve(SNES snes,Vec b,Vec x)
4446: {
4447:   PetscErrorCode    ierr;
4448:   PetscBool         flg;
4449:   PetscInt          grid;
4450:   Vec               xcreated = NULL;
4451:   DM                dm;


4460:   /* High level operations using the nonlinear solver */
4461:   {
4462:     PetscViewer       viewer;
4463:     PetscViewerFormat format;
4464:     PetscInt          num;
4465:     PetscBool         flg;
4466:     static PetscBool  incall = PETSC_FALSE;

4468:     if (!incall) {
4469:       /* Estimate the convergence rate of the discretization */
4470:       PetscOptionsGetViewer(PetscObjectComm((PetscObject) snes),((PetscObject)snes)->options, ((PetscObject) snes)->prefix, "-snes_convergence_estimate", &viewer, &format, &flg);
4471:       if (flg) {
4472:         PetscConvEst conv;
4473:         DM           dm;
4474:         PetscReal   *alpha; /* Convergence rate of the solution error for each field in the L_2 norm */
4475:         PetscInt     Nf;

4477:         incall = PETSC_TRUE;
4478:         SNESGetDM(snes, &dm);
4479:         DMGetNumFields(dm, &Nf);
4480:         PetscCalloc1(Nf, &alpha);
4481:         PetscConvEstCreate(PetscObjectComm((PetscObject) snes), &conv);
4482:         PetscConvEstSetSolver(conv, (PetscObject) snes);
4483:         PetscConvEstSetFromOptions(conv);
4484:         PetscConvEstSetUp(conv);
4485:         PetscConvEstGetConvRate(conv, alpha);
4486:         PetscViewerPushFormat(viewer, format);
4487:         PetscConvEstRateView(conv, alpha, viewer);
4488:         PetscViewerPopFormat(viewer);
4489:         PetscViewerDestroy(&viewer);
4490:         PetscConvEstDestroy(&conv);
4491:         PetscFree(alpha);
4492:         incall = PETSC_FALSE;
4493:       }
4494:       /* Adaptively refine the initial grid */
4495:       num  = 1;
4496:       PetscOptionsGetInt(NULL, ((PetscObject) snes)->prefix, "-snes_adapt_initial", &num, &flg);
4497:       if (flg) {
4498:         DMAdaptor adaptor;

4500:         incall = PETSC_TRUE;
4501:         DMAdaptorCreate(PetscObjectComm((PetscObject)snes), &adaptor);
4502:         DMAdaptorSetSolver(adaptor, snes);
4503:         DMAdaptorSetSequenceLength(adaptor, num);
4504:         DMAdaptorSetFromOptions(adaptor);
4505:         DMAdaptorSetUp(adaptor);
4506:         DMAdaptorAdapt(adaptor, x, DM_ADAPTATION_INITIAL, &dm, &x);
4507:         DMAdaptorDestroy(&adaptor);
4508:         incall = PETSC_FALSE;
4509:       }
4510:       /* Use grid sequencing to adapt */
4511:       num  = 0;
4512:       PetscOptionsGetInt(NULL, ((PetscObject) snes)->prefix, "-snes_adapt_sequence", &num, NULL);
4513:       if (num) {
4514:         DMAdaptor adaptor;

4516:         incall = PETSC_TRUE;
4517:         DMAdaptorCreate(PetscObjectComm((PetscObject)snes), &adaptor);
4518:         DMAdaptorSetSolver(adaptor, snes);
4519:         DMAdaptorSetSequenceLength(adaptor, num);
4520:         DMAdaptorSetFromOptions(adaptor);
4521:         DMAdaptorSetUp(adaptor);
4522:         DMAdaptorAdapt(adaptor, x, DM_ADAPTATION_SEQUENTIAL, &dm, &x);
4523:         DMAdaptorDestroy(&adaptor);
4524:         incall = PETSC_FALSE;
4525:       }
4526:     }
4527:   }
4528:   if (!x) {
4529:     SNESGetDM(snes,&dm);
4530:     DMCreateGlobalVector(dm,&xcreated);
4531:     x    = xcreated;
4532:   }
4533:   SNESViewFromOptions(snes,NULL,"-snes_view_pre");

4535:   for (grid=0; grid<snes->gridsequence; grid++) {PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));}
4536:   for (grid=0; grid<snes->gridsequence+1; grid++) {

4538:     /* set solution vector */
4539:     if (!grid) {PetscObjectReference((PetscObject)x);}
4540:     VecDestroy(&snes->vec_sol);
4541:     snes->vec_sol = x;
4542:     SNESGetDM(snes,&dm);

4544:     /* set affine vector if provided */
4545:     if (b) { PetscObjectReference((PetscObject)b); }
4546:     VecDestroy(&snes->vec_rhs);
4547:     snes->vec_rhs = b;

4549:     if (snes->vec_rhs && (snes->vec_func == snes->vec_rhs)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Right hand side vector cannot be function vector");
4550:     if (snes->vec_func == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be function vector");
4551:     if (snes->vec_rhs  == snes->vec_sol) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_IDN,"Solution vector cannot be right hand side vector");
4552:     if (!snes->vec_sol_update /* && snes->vec_sol */) {
4553:       VecDuplicate(snes->vec_sol,&snes->vec_sol_update);
4554:       PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->vec_sol_update);
4555:     }
4556:     DMShellSetGlobalVector(dm,snes->vec_sol);
4557:     SNESSetUp(snes);

4559:     if (!grid) {
4560:       if (snes->ops->computeinitialguess) {
4561:         (*snes->ops->computeinitialguess)(snes,snes->vec_sol,snes->initialguessP);
4562:       }
4563:     }

4565:     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
4566:     if (snes->counters_reset) {snes->nfuncs = 0; snes->linear_its = 0; snes->numFailures = 0;}

4568:     PetscLogEventBegin(SNES_Solve,snes,0,0,0);
4569:     (*snes->ops->solve)(snes);
4570:     PetscLogEventEnd(SNES_Solve,snes,0,0,0);
4571:     if (!snes->reason) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Internal error, solver returned without setting converged reason");
4572:     snes->domainerror = PETSC_FALSE; /* clear the flag if it has been set */

4574:     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
4575:     if (snes->lagpre_persist) snes->pre_iter += snes->iter;

4577:     PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes),((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-snes_test_local_min",NULL,NULL,&flg);
4578:     if (flg && !PetscPreLoadingOn) { SNESTestLocalMin(snes); }
4579:     SNESConvergedReasonViewFromOptions(snes);

4581:     if (snes->errorifnotconverged && snes->reason < 0) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_NOT_CONVERGED,"SNESSolve has not converged");
4582:     if (snes->reason < 0) break;
4583:     if (grid <  snes->gridsequence) {
4584:       DM  fine;
4585:       Vec xnew;
4586:       Mat interp;

4588:       DMRefine(snes->dm,PetscObjectComm((PetscObject)snes),&fine);
4589:       if (!fine) SETERRQ(PetscObjectComm((PetscObject)snes),PETSC_ERR_ARG_INCOMP,"DMRefine() did not perform any refinement, cannot continue grid sequencing");
4590:       DMCreateInterpolation(snes->dm,fine,&interp,NULL);
4591:       DMCreateGlobalVector(fine,&xnew);
4592:       MatInterpolate(interp,x,xnew);
4593:       DMInterpolate(snes->dm,interp,fine);
4594:       MatDestroy(&interp);
4595:       x    = xnew;

4597:       SNESReset(snes);
4598:       SNESSetDM(snes,fine);
4599:       SNESResetFromOptions(snes);
4600:       DMDestroy(&fine);
4601:       PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes)));
4602:     }
4603:   }
4604:   SNESViewFromOptions(snes,NULL,"-snes_view");
4605:   VecViewFromOptions(snes->vec_sol,(PetscObject)snes,"-snes_view_solution");
4606:   DMMonitor(snes->dm);

4608:   VecDestroy(&xcreated);
4609:   PetscObjectSAWsBlock((PetscObject)snes);
4610:   return(0);
4611: }

4613: /* --------- Internal routines for SNES Package --------- */

4615: /*@C
4616:    SNESSetType - Sets the method for the nonlinear solver.

4618:    Collective on SNES

4620:    Input Parameters:
4621: +  snes - the SNES context
4622: -  type - a known method

4624:    Options Database Key:
4625: .  -snes_type <type> - Sets the method; use -help for a list
4626:    of available methods (for instance, newtonls or newtontr)

4628:    Notes:
4629:    See "petsc/include/petscsnes.h" for available methods (for instance)
4630: +    SNESNEWTONLS - Newton's method with line search
4631:      (systems of nonlinear equations)
4632: -    SNESNEWTONTR - Newton's method with trust region
4633:      (systems of nonlinear equations)

4635:   Normally, it is best to use the SNESSetFromOptions() command and then
4636:   set the SNES solver type from the options database rather than by using
4637:   this routine.  Using the options database provides the user with
4638:   maximum flexibility in evaluating the many nonlinear solvers.
4639:   The SNESSetType() routine is provided for those situations where it
4640:   is necessary to set the nonlinear solver independently of the command
4641:   line or options database.  This might be the case, for example, when
4642:   the choice of solver changes during the execution of the program,
4643:   and the user's application is taking responsibility for choosing the
4644:   appropriate method.

4646:     Developer Notes:
4647:     SNESRegister() adds a constructor for a new SNESType to SNESList, SNESSetType() locates
4648:     the constructor in that list and calls it to create the spexific object.

4650:   Level: intermediate

4652: .seealso: SNESType, SNESCreate(), SNESDestroy(), SNESGetType(), SNESSetFromOptions()

4654: @*/
4655: PetscErrorCode  SNESSetType(SNES snes,SNESType type)
4656: {
4657:   PetscErrorCode ierr,(*r)(SNES);
4658:   PetscBool      match;


4664:   PetscObjectTypeCompare((PetscObject)snes,type,&match);
4665:   if (match) return(0);

4667:   PetscFunctionListFind(SNESList,type,&r);
4668:   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested SNES type %s",type);
4669:   /* Destroy the previous private SNES context */
4670:   if (snes->ops->destroy) {
4671:     (*(snes)->ops->destroy)(snes);
4672:     snes->ops->destroy = NULL;
4673:   }
4674:   /* Reinitialize function pointers in SNESOps structure */
4675:   snes->ops->setup          = NULL;
4676:   snes->ops->solve          = NULL;
4677:   snes->ops->view           = NULL;
4678:   snes->ops->setfromoptions = NULL;
4679:   snes->ops->destroy        = NULL;

4681:   /* It may happen the user has customized the line search before calling SNESSetType */
4682:   if (((PetscObject)snes)->type_name) {
4683:     SNESLineSearchDestroy(&snes->linesearch);
4684:   }

4686:   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
4687:   snes->setupcalled = PETSC_FALSE;

4689:   PetscObjectChangeTypeName((PetscObject)snes,type);
4690:   (*r)(snes);
4691:   return(0);
4692: }

4694: /*@C
4695:    SNESGetType - Gets the SNES method type and name (as a string).

4697:    Not Collective

4699:    Input Parameter:
4700: .  snes - nonlinear solver context

4702:    Output Parameter:
4703: .  type - SNES method (a character string)

4705:    Level: intermediate

4707: @*/
4708: PetscErrorCode  SNESGetType(SNES snes,SNESType *type)
4709: {
4713:   *type = ((PetscObject)snes)->type_name;
4714:   return(0);
4715: }

4717: /*@
4718:   SNESSetSolution - Sets the solution vector for use by the SNES routines.

4720:   Logically Collective on SNES

4722:   Input Parameters:
4723: + snes - the SNES context obtained from SNESCreate()
4724: - u    - the solution vector

4726:   Level: beginner

4728: @*/
4729: PetscErrorCode SNESSetSolution(SNES snes, Vec u)
4730: {
4731:   DM             dm;

4737:   PetscObjectReference((PetscObject) u);
4738:   VecDestroy(&snes->vec_sol);

4740:   snes->vec_sol = u;

4742:   SNESGetDM(snes, &dm);
4743:   DMShellSetGlobalVector(dm, u);
4744:   return(0);
4745: }

4747: /*@
4748:    SNESGetSolution - Returns the vector where the approximate solution is
4749:    stored. This is the fine grid solution when using SNESSetGridSequence().

4751:    Not Collective, but Vec is parallel if SNES is parallel

4753:    Input Parameter:
4754: .  snes - the SNES context

4756:    Output Parameter:
4757: .  x - the solution

4759:    Level: intermediate

4761: .seealso:  SNESGetSolutionUpdate(), SNESGetFunction()
4762: @*/
4763: PetscErrorCode  SNESGetSolution(SNES snes,Vec *x)
4764: {
4768:   *x = snes->vec_sol;
4769:   return(0);
4770: }

4772: /*@
4773:    SNESGetSolutionUpdate - Returns the vector where the solution update is
4774:    stored.

4776:    Not Collective, but Vec is parallel if SNES is parallel

4778:    Input Parameter:
4779: .  snes - the SNES context

4781:    Output Parameter:
4782: .  x - the solution update

4784:    Level: advanced

4786: .seealso: SNESGetSolution(), SNESGetFunction()
4787: @*/
4788: PetscErrorCode  SNESGetSolutionUpdate(SNES snes,Vec *x)
4789: {
4793:   *x = snes->vec_sol_update;
4794:   return(0);
4795: }

4797: /*@C
4798:    SNESGetFunction - Returns the vector where the function is stored.

4800:    Not Collective, but Vec is parallel if SNES is parallel. Collective if Vec is requested, but has not been created yet.

4802:    Input Parameter:
4803: .  snes - the SNES context

4805:    Output Parameter:
4806: +  r - the vector that is used to store residuals (or NULL if you don't want it)
4807: .  f - the function (or NULL if you don't want it); see SNESFunction for calling sequence details
4808: -  ctx - the function context (or NULL if you don't want it)

4810:    Level: advanced

4812:     Notes: The vector r DOES NOT, in general contain the current value of the SNES nonlinear function

4814: .seealso: SNESSetFunction(), SNESGetSolution(), SNESFunction
4815: @*/
4816: PetscErrorCode  SNESGetFunction(SNES snes,Vec *r,PetscErrorCode (**f)(SNES,Vec,Vec,void*),void **ctx)
4817: {
4819:   DM             dm;

4823:   if (r) {
4824:     if (!snes->vec_func) {
4825:       if (snes->vec_rhs) {
4826:         VecDuplicate(snes->vec_rhs,&snes->vec_func);
4827:       } else if (snes->vec_sol) {
4828:         VecDuplicate(snes->vec_sol,&snes->vec_func);
4829:       } else if (snes->dm) {
4830:         DMCreateGlobalVector(snes->dm,&snes->vec_func);
4831:       }
4832:     }
4833:     *r = snes->vec_func;
4834:   }
4835:   SNESGetDM(snes,&dm);
4836:   DMSNESGetFunction(dm,f,ctx);
4837:   return(0);
4838: }

4840: /*@C
4841:    SNESGetNGS - Returns the NGS function and context.

4843:    Input Parameter:
4844: .  snes - the SNES context

4846:    Output Parameter:
4847: +  f - the function (or NULL) see SNESNGSFunction for details
4848: -  ctx    - the function context (or NULL)

4850:    Level: advanced

4852: .seealso: SNESSetNGS(), SNESGetFunction()
4853: @*/

4855: PetscErrorCode SNESGetNGS (SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void*), void ** ctx)
4856: {
4858:   DM             dm;

4862:   SNESGetDM(snes,&dm);
4863:   DMSNESGetNGS(dm,f,ctx);
4864:   return(0);
4865: }

4867: /*@C
4868:    SNESSetOptionsPrefix - Sets the prefix used for searching for all
4869:    SNES options in the database.

4871:    Logically Collective on SNES

4873:    Input Parameter:
4874: +  snes - the SNES context
4875: -  prefix - the prefix to prepend to all option names

4877:    Notes:
4878:    A hyphen (-) must NOT be given at the beginning of the prefix name.
4879:    The first character of all runtime options is AUTOMATICALLY the hyphen.

4881:    Level: advanced

4883: .seealso: SNESSetFromOptions()
4884: @*/
4885: PetscErrorCode  SNESSetOptionsPrefix(SNES snes,const char prefix[])
4886: {

4891:   PetscObjectSetOptionsPrefix((PetscObject)snes,prefix);
4892:   if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
4893:   if (snes->linesearch) {
4894:     SNESGetLineSearch(snes,&snes->linesearch);
4895:     PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch,prefix);
4896:   }
4897:   KSPSetOptionsPrefix(snes->ksp,prefix);
4898:   return(0);
4899: }

4901: /*@C
4902:    SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4903:    SNES options in the database.

4905:    Logically Collective on SNES

4907:    Input Parameters:
4908: +  snes - the SNES context
4909: -  prefix - the prefix to prepend to all option names

4911:    Notes:
4912:    A hyphen (-) must NOT be given at the beginning of the prefix name.
4913:    The first character of all runtime options is AUTOMATICALLY the hyphen.

4915:    Level: advanced

4917: .seealso: SNESGetOptionsPrefix()
4918: @*/
4919: PetscErrorCode  SNESAppendOptionsPrefix(SNES snes,const char prefix[])
4920: {

4925:   PetscObjectAppendOptionsPrefix((PetscObject)snes,prefix);
4926:   if (!snes->ksp) {SNESGetKSP(snes,&snes->ksp);}
4927:   if (snes->linesearch) {
4928:     SNESGetLineSearch(snes,&snes->linesearch);
4929:     PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch,prefix);
4930:   }
4931:   KSPAppendOptionsPrefix(snes->ksp,prefix);
4932:   return(0);
4933: }

4935: /*@C
4936:    SNESGetOptionsPrefix - Sets the prefix used for searching for all
4937:    SNES options in the database.

4939:    Not Collective

4941:    Input Parameter:
4942: .  snes - the SNES context

4944:    Output Parameter:
4945: .  prefix - pointer to the prefix string used

4947:    Notes:
4948:     On the fortran side, the user should pass in a string 'prefix' of
4949:    sufficient length to hold the prefix.

4951:    Level: advanced

4953: .seealso: SNESAppendOptionsPrefix()
4954: @*/
4955: PetscErrorCode  SNESGetOptionsPrefix(SNES snes,const char *prefix[])
4956: {

4961:   PetscObjectGetOptionsPrefix((PetscObject)snes,prefix);
4962:   return(0);
4963: }


4966: /*@C
4967:   SNESRegister - Adds a method to the nonlinear solver package.

4969:    Not collective

4971:    Input Parameters:
4972: +  name_solver - name of a new user-defined solver
4973: -  routine_create - routine to create method context

4975:    Notes:
4976:    SNESRegister() may be called multiple times to add several user-defined solvers.

4978:    Sample usage:
4979: .vb
4980:    SNESRegister("my_solver",MySolverCreate);
4981: .ve

4983:    Then, your solver can be chosen with the procedural interface via
4984: $     SNESSetType(snes,"my_solver")
4985:    or at runtime via the option
4986: $     -snes_type my_solver

4988:    Level: advanced

4990:     Note: If your function is not being put into a shared library then use SNESRegister() instead

4992: .seealso: SNESRegisterAll(), SNESRegisterDestroy()

4994:   Level: advanced
4995: @*/
4996: PetscErrorCode  SNESRegister(const char sname[],PetscErrorCode (*function)(SNES))
4997: {

5001:   SNESInitializePackage();
5002:   PetscFunctionListAdd(&SNESList,sname,function);
5003:   return(0);
5004: }

5006: PetscErrorCode  SNESTestLocalMin(SNES snes)
5007: {
5009:   PetscInt       N,i,j;
5010:   Vec            u,uh,fh;
5011:   PetscScalar    value;
5012:   PetscReal      norm;

5015:   SNESGetSolution(snes,&u);
5016:   VecDuplicate(u,&uh);
5017:   VecDuplicate(u,&fh);

5019:   /* currently only works for sequential */
5020:   PetscPrintf(PetscObjectComm((PetscObject)snes),"Testing FormFunction() for local min\n");
5021:   VecGetSize(u,&N);
5022:   for (i=0; i<N; i++) {
5023:     VecCopy(u,uh);
5024:     PetscPrintf(PetscObjectComm((PetscObject)snes),"i = %D\n",i);
5025:     for (j=-10; j<11; j++) {
5026:       value = PetscSign(j)*PetscExpReal(PetscAbs(j)-10.0);
5027:       VecSetValue(uh,i,value,ADD_VALUES);
5028:       SNESComputeFunction(snes,uh,fh);
5029:       VecNorm(fh,NORM_2,&norm);
5030:       PetscPrintf(PetscObjectComm((PetscObject)snes),"       j norm %D %18.16e\n",j,norm);
5031:       value = -value;
5032:       VecSetValue(uh,i,value,ADD_VALUES);
5033:     }
5034:   }
5035:   VecDestroy(&uh);
5036:   VecDestroy(&fh);
5037:   return(0);
5038: }

5040: /*@
5041:    SNESKSPSetUseEW - Sets SNES use Eisenstat-Walker method for
5042:    computing relative tolerance for linear solvers within an inexact
5043:    Newton method.

5045:    Logically Collective on SNES

5047:    Input Parameters:
5048: +  snes - SNES context
5049: -  flag - PETSC_TRUE or PETSC_FALSE

5051:     Options Database:
5052: +  -snes_ksp_ew - use Eisenstat-Walker method for determining linear system convergence
5053: .  -snes_ksp_ew_version ver - version of  Eisenstat-Walker method
5054: .  -snes_ksp_ew_rtol0 <rtol0> - Sets rtol0
5055: .  -snes_ksp_ew_rtolmax <rtolmax> - Sets rtolmax
5056: .  -snes_ksp_ew_gamma <gamma> - Sets gamma
5057: .  -snes_ksp_ew_alpha <alpha> - Sets alpha
5058: .  -snes_ksp_ew_alpha2 <alpha2> - Sets alpha2
5059: -  -snes_ksp_ew_threshold <threshold> - Sets threshold

5061:    Notes:
5062:    Currently, the default is to use a constant relative tolerance for
5063:    the inner linear solvers.  Alternatively, one can use the
5064:    Eisenstat-Walker method, where the relative convergence tolerance
5065:    is reset at each Newton iteration according progress of the nonlinear
5066:    solver.

5068:    Level: advanced

5070:    Reference:
5071:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
5072:    inexact Newton method", SISC 17 (1), pp.16-32, 1996.

5074: .seealso: SNESKSPGetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
5075: @*/
5076: PetscErrorCode  SNESKSPSetUseEW(SNES snes,PetscBool flag)
5077: {
5081:   snes->ksp_ewconv = flag;
5082:   return(0);
5083: }

5085: /*@
5086:    SNESKSPGetUseEW - Gets if SNES is using Eisenstat-Walker method
5087:    for computing relative tolerance for linear solvers within an
5088:    inexact Newton method.

5090:    Not Collective

5092:    Input Parameter:
5093: .  snes - SNES context

5095:    Output Parameter:
5096: .  flag - PETSC_TRUE or PETSC_FALSE

5098:    Notes:
5099:    Currently, the default is to use a constant relative tolerance for
5100:    the inner linear solvers.  Alternatively, one can use the
5101:    Eisenstat-Walker method, where the relative convergence tolerance
5102:    is reset at each Newton iteration according progress of the nonlinear
5103:    solver.

5105:    Level: advanced

5107:    Reference:
5108:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
5109:    inexact Newton method", SISC 17 (1), pp.16-32, 1996.

5111: .seealso: SNESKSPSetUseEW(), SNESKSPGetParametersEW(), SNESKSPSetParametersEW()
5112: @*/
5113: PetscErrorCode  SNESKSPGetUseEW(SNES snes, PetscBool  *flag)
5114: {
5118:   *flag = snes->ksp_ewconv;
5119:   return(0);
5120: }

5122: /*@
5123:    SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
5124:    convergence criteria for the linear solvers within an inexact
5125:    Newton method.

5127:    Logically Collective on SNES

5129:    Input Parameters:
5130: +    snes - SNES context
5131: .    version - version 1, 2 (default is 2) or 3
5132: .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
5133: .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
5134: .    gamma - multiplicative factor for version 2 rtol computation
5135:              (0 <= gamma2 <= 1)
5136: .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
5137: .    alpha2 - power for safeguard
5138: -    threshold - threshold for imposing safeguard (0 < threshold < 1)

5140:    Note:
5141:    Version 3 was contributed by Luis Chacon, June 2006.

5143:    Use PETSC_DEFAULT to retain the default for any of the parameters.

5145:    Level: advanced

5147:    Reference:
5148:    S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an
5149:    inexact Newton method", Utah State University Math. Stat. Dept. Res.
5150:    Report 6/94/75, June, 1994, to appear in SIAM J. Sci. Comput.

5152: .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPGetParametersEW()
5153: @*/
5154: PetscErrorCode  SNESKSPSetParametersEW(SNES snes,PetscInt version,PetscReal rtol_0,PetscReal rtol_max,PetscReal gamma,PetscReal alpha,PetscReal alpha2,PetscReal threshold)
5155: {
5156:   SNESKSPEW *kctx;

5160:   kctx = (SNESKSPEW*)snes->kspconvctx;
5161:   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");

5170:   if (version != PETSC_DEFAULT)   kctx->version   = version;
5171:   if (rtol_0 != PETSC_DEFAULT)    kctx->rtol_0    = rtol_0;
5172:   if (rtol_max != PETSC_DEFAULT)  kctx->rtol_max  = rtol_max;
5173:   if (gamma != PETSC_DEFAULT)     kctx->gamma     = gamma;
5174:   if (alpha != PETSC_DEFAULT)     kctx->alpha     = alpha;
5175:   if (alpha2 != PETSC_DEFAULT)    kctx->alpha2    = alpha2;
5176:   if (threshold != PETSC_DEFAULT) kctx->threshold = threshold;

5178:   if (kctx->version < 1 || kctx->version > 3) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 and 3 are supported: %D",kctx->version);
5179:   if (kctx->rtol_0 < 0.0 || kctx->rtol_0 >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_0 < 1.0: %g",(double)kctx->rtol_0);
5180:   if (kctx->rtol_max < 0.0 || kctx->rtol_max >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= rtol_max (%g) < 1.0\n",(double)kctx->rtol_max);
5181:   if (kctx->gamma < 0.0 || kctx->gamma > 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 <= gamma (%g) <= 1.0\n",(double)kctx->gamma);
5182:   if (kctx->alpha <= 1.0 || kctx->alpha > 2.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"1.0 < alpha (%g) <= 2.0\n",(double)kctx->alpha);
5183:   if (kctx->threshold <= 0.0 || kctx->threshold >= 1.0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"0.0 < threshold (%g) < 1.0\n",(double)kctx->threshold);
5184:   return(0);
5185: }

5187: /*@
5188:    SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
5189:    convergence criteria for the linear solvers within an inexact
5190:    Newton method.

5192:    Not Collective

5194:    Input Parameters:
5195:      snes - SNES context

5197:    Output Parameters:
5198: +    version - version 1, 2 (default is 2) or 3
5199: .    rtol_0 - initial relative tolerance (0 <= rtol_0 < 1)
5200: .    rtol_max - maximum relative tolerance (0 <= rtol_max < 1)
5201: .    gamma - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
5202: .    alpha - power for version 2 rtol computation (1 < alpha <= 2)
5203: .    alpha2 - power for safeguard
5204: -    threshold - threshold for imposing safeguard (0 < threshold < 1)

5206:    Level: advanced

5208: .seealso: SNESKSPSetUseEW(), SNESKSPGetUseEW(), SNESKSPSetParametersEW()
5209: @*/
5210: PetscErrorCode  SNESKSPGetParametersEW(SNES snes,PetscInt *version,PetscReal *rtol_0,PetscReal *rtol_max,PetscReal *gamma,PetscReal *alpha,PetscReal *alpha2,PetscReal *threshold)
5211: {
5212:   SNESKSPEW *kctx;

5216:   kctx = (SNESKSPEW*)snes->kspconvctx;
5217:   if (!kctx) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"No Eisenstat-Walker context existing");
5218:   if (version)   *version   = kctx->version;
5219:   if (rtol_0)    *rtol_0    = kctx->rtol_0;
5220:   if (rtol_max)  *rtol_max  = kctx->rtol_max;
5221:   if (gamma)     *gamma     = kctx->gamma;
5222:   if (alpha)     *alpha     = kctx->alpha;
5223:   if (alpha2)    *alpha2    = kctx->alpha2;
5224:   if (threshold) *threshold = kctx->threshold;
5225:   return(0);
5226: }

5228:  PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
5229: {
5231:   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
5232:   PetscReal      rtol  = PETSC_DEFAULT,stol;

5235:   if (!snes->ksp_ewconv) return(0);
5236:   if (!snes->iter) {
5237:     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
5238:     VecNorm(snes->vec_func,NORM_2,&kctx->norm_first);
5239:   }
5240:   else {
5241:     if (kctx->version == 1) {
5242:       rtol = (snes->norm - kctx->lresid_last)/kctx->norm_last;
5243:       if (rtol < 0.0) rtol = -rtol;
5244:       stol = PetscPowReal(kctx->rtol_last,kctx->alpha2);
5245:       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
5246:     } else if (kctx->version == 2) {
5247:       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
5248:       stol = kctx->gamma * PetscPowReal(kctx->rtol_last,kctx->alpha);
5249:       if (stol > kctx->threshold) rtol = PetscMax(rtol,stol);
5250:     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
5251:       rtol = kctx->gamma * PetscPowReal(snes->norm/kctx->norm_last,kctx->alpha);
5252:       /* safeguard: avoid sharp decrease of rtol */
5253:       stol = kctx->gamma*PetscPowReal(kctx->rtol_last,kctx->alpha);
5254:       stol = PetscMax(rtol,stol);
5255:       rtol = PetscMin(kctx->rtol_0,stol);
5256:       /* safeguard: avoid oversolving */
5257:       stol = kctx->gamma*(kctx->norm_first*snes->rtol)/snes->norm;
5258:       stol = PetscMax(rtol,stol);
5259:       rtol = PetscMin(kctx->rtol_0,stol);
5260:     } else SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Only versions 1, 2 or 3 are supported: %D",kctx->version);
5261:   }
5262:   /* safeguard: avoid rtol greater than one */
5263:   rtol = PetscMin(rtol,kctx->rtol_max);
5264:   KSPSetTolerances(ksp,rtol,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT);
5265:   PetscInfo3(snes,"iter %D, Eisenstat-Walker (version %D) KSP rtol=%g\n",snes->iter,kctx->version,(double)rtol);
5266:   return(0);
5267: }

5269: PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, SNES snes)
5270: {
5272:   SNESKSPEW      *kctx = (SNESKSPEW*)snes->kspconvctx;
5273:   PCSide         pcside;
5274:   Vec            lres;

5277:   if (!snes->ksp_ewconv) return(0);
5278:   KSPGetTolerances(ksp,&kctx->rtol_last,NULL,NULL,NULL);
5279:   kctx->norm_last = snes->norm;
5280:   if (kctx->version == 1) {
5281:     PC        pc;
5282:     PetscBool isNone;

5284:     KSPGetPC(ksp, &pc);
5285:     PetscObjectTypeCompare((PetscObject) pc, PCNONE, &isNone);
5286:     KSPGetPCSide(ksp,&pcside);
5287:      if (pcside == PC_RIGHT || isNone) { /* XXX Should we also test KSP_UNPRECONDITIONED_NORM ? */
5288:       /* KSP residual is true linear residual */
5289:       KSPGetResidualNorm(ksp,&kctx->lresid_last);
5290:     } else {
5291:       /* KSP residual is preconditioned residual */
5292:       /* compute true linear residual norm */
5293:       VecDuplicate(b,&lres);
5294:       MatMult(snes->jacobian,x,lres);
5295:       VecAYPX(lres,-1.0,b);
5296:       VecNorm(lres,NORM_2,&kctx->lresid_last);
5297:       VecDestroy(&lres);
5298:     }
5299:   }
5300:   return(0);
5301: }

5303: /*@
5304:    SNESGetKSP - Returns the KSP context for a SNES solver.

5306:    Not Collective, but if SNES object is parallel, then KSP object is parallel

5308:    Input Parameter:
5309: .  snes - the SNES context

5311:    Output Parameter:
5312: .  ksp - the KSP context

5314:    Notes:
5315:    The user can then directly manipulate the KSP context to set various
5316:    options, etc.  Likewise, the user can then extract and manipulate the
5317:    PC contexts as well.

5319:    Level: beginner

5321: .seealso: KSPGetPC(), SNESCreate(), KSPCreate(), SNESSetKSP()
5322: @*/
5323: PetscErrorCode  SNESGetKSP(SNES snes,KSP *ksp)
5324: {


5331:   if (!snes->ksp) {
5332:     PetscBool monitor = PETSC_FALSE;

5334:     KSPCreate(PetscObjectComm((PetscObject)snes),&snes->ksp);
5335:     PetscObjectIncrementTabLevel((PetscObject)snes->ksp,(PetscObject)snes,1);
5336:     PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->ksp);

5338:     KSPSetPreSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPreSolve_SNESEW,snes);
5339:     KSPSetPostSolve(snes->ksp,(PetscErrorCode (*)(KSP,Vec,Vec,void*))KSPPostSolve_SNESEW,snes);

5341:     PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes",&monitor,NULL);
5342:     if (monitor) {
5343:       KSPMonitorSet(snes->ksp,KSPMonitorSNES,snes,NULL);
5344:     }
5345:     monitor = PETSC_FALSE;
5346:     PetscOptionsGetBool(((PetscObject)snes)->options,((PetscObject)snes)->prefix,"-ksp_monitor_snes_lg",&monitor,NULL);
5347:     if (monitor) {
5348:       PetscObject *objs;
5349:       KSPMonitorSNESLGResidualNormCreate(PetscObjectComm((PetscObject)snes),NULL,NULL,PETSC_DECIDE,PETSC_DECIDE,600,600,&objs);
5350:       objs[0] = (PetscObject) snes;
5351:       KSPMonitorSet(snes->ksp,(PetscErrorCode (*)(KSP,PetscInt,PetscReal,void*))KSPMonitorSNESLGResidualNorm,objs,(PetscErrorCode (*)(void**))KSPMonitorSNESLGResidualNormDestroy);
5352:     }
5353:     PetscObjectSetOptions((PetscObject)snes->ksp,((PetscObject)snes)->options);
5354:   }
5355:   *ksp = snes->ksp;
5356:   return(0);
5357: }


5360: #include <petsc/private/dmimpl.h>
5361: /*@
5362:    SNESSetDM - Sets the DM that may be used by some nonlinear solvers or their underlying preconditioners

5364:    Logically Collective on SNES

5366:    Input Parameters:
5367: +  snes - the nonlinear solver context
5368: -  dm - the dm, cannot be NULL

5370:    Notes:
5371:    A DM can only be used for solving one problem at a time because information about the problem is stored on the DM,
5372:    even when not using interfaces like DMSNESSetFunction().  Use DMClone() to get a distinct DM when solving different
5373:    problems using the same function space.

5375:    Level: intermediate

5377: .seealso: SNESGetDM(), KSPSetDM(), KSPGetDM()
5378: @*/
5379: PetscErrorCode  SNESSetDM(SNES snes,DM dm)
5380: {
5382:   KSP            ksp;
5383:   DMSNES         sdm;

5388:   PetscObjectReference((PetscObject)dm);
5389:   if (snes->dm) {               /* Move the DMSNES context over to the new DM unless the new DM already has one */
5390:     if (snes->dm->dmsnes && !dm->dmsnes) {
5391:       DMCopyDMSNES(snes->dm,dm);
5392:       DMGetDMSNES(snes->dm,&sdm);
5393:       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
5394:     }
5395:     DMCoarsenHookRemove(snes->dm,DMCoarsenHook_SNESVecSol,DMRestrictHook_SNESVecSol,snes);
5396:     DMDestroy(&snes->dm);
5397:   }
5398:   snes->dm     = dm;
5399:   snes->dmAuto = PETSC_FALSE;

5401:   SNESGetKSP(snes,&ksp);
5402:   KSPSetDM(ksp,dm);
5403:   KSPSetDMActive(ksp,PETSC_FALSE);
5404:   if (snes->npc) {
5405:     SNESSetDM(snes->npc, snes->dm);
5406:     SNESSetNPCSide(snes,snes->npcside);
5407:   }
5408:   return(0);
5409: }

5411: /*@
5412:    SNESGetDM - Gets the DM that may be used by some preconditioners

5414:    Not Collective but DM obtained is parallel on SNES

5416:    Input Parameter:
5417: . snes - the preconditioner context

5419:    Output Parameter:
5420: .  dm - the dm

5422:    Level: intermediate

5424: .seealso: SNESSetDM(), KSPSetDM(), KSPGetDM()
5425: @*/
5426: PetscErrorCode  SNESGetDM(SNES snes,DM *dm)
5427: {

5432:   if (!snes->dm) {
5433:     DMShellCreate(PetscObjectComm((PetscObject)snes),&snes->dm);
5434:     snes->dmAuto = PETSC_TRUE;
5435:   }
5436:   *dm = snes->dm;
5437:   return(0);
5438: }

5440: /*@
5441:   SNESSetNPC - Sets the nonlinear preconditioner to be used.

5443:   Collective on SNES

5445:   Input Parameters:
5446: + snes - iterative context obtained from SNESCreate()
5447: - pc   - the preconditioner object

5449:   Notes:
5450:   Use SNESGetNPC() to retrieve the preconditioner context (for example,
5451:   to configure it using the API).

5453:   Level: developer

5455: .seealso: SNESGetNPC(), SNESHasNPC()
5456: @*/
5457: PetscErrorCode SNESSetNPC(SNES snes, SNES pc)
5458: {

5465:   PetscObjectReference((PetscObject) pc);
5466:   SNESDestroy(&snes->npc);
5467:   snes->npc = pc;
5468:   PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->npc);
5469:   return(0);
5470: }

5472: /*@
5473:   SNESGetNPC - Creates a nonlinear preconditioning solver (SNES) to be used to precondition the nonlinear solver.

5475:   Not Collective; but any changes to the obtained SNES object must be applied collectively

5477:   Input Parameter:
5478: . snes - iterative context obtained from SNESCreate()

5480:   Output Parameter:
5481: . pc - preconditioner context

5483:   Options Database:
5484: . -npc_snes_type <type> - set the type of the SNES to use as the nonlinear preconditioner

5486:   Notes:
5487:     If a SNES was previously set with SNESSetNPC() then that SNES is returned, otherwise a new SNES object is created.

5489:     The (preconditioner) SNES returned automatically inherits the same nonlinear function and Jacobian supplied to the original
5490:     SNES during SNESSetUp()

5492:   Level: developer

5494: .seealso: SNESSetNPC(), SNESHasNPC(), SNES, SNESCreate()
5495: @*/
5496: PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
5497: {
5499:   const char     *optionsprefix;

5504:   if (!snes->npc) {
5505:     SNESCreate(PetscObjectComm((PetscObject)snes),&snes->npc);
5506:     PetscObjectIncrementTabLevel((PetscObject)snes->npc,(PetscObject)snes,1);
5507:     PetscLogObjectParent((PetscObject)snes,(PetscObject)snes->npc);
5508:     SNESGetOptionsPrefix(snes,&optionsprefix);
5509:     SNESSetOptionsPrefix(snes->npc,optionsprefix);
5510:     SNESAppendOptionsPrefix(snes->npc,"npc_");
5511:     SNESSetCountersReset(snes->npc,PETSC_FALSE);
5512:   }
5513:   *pc = snes->npc;
5514:   return(0);
5515: }

5517: /*@
5518:   SNESHasNPC - Returns whether a nonlinear preconditioner exists

5520:   Not Collective

5522:   Input Parameter:
5523: . snes - iterative context obtained from SNESCreate()

5525:   Output Parameter:
5526: . has_npc - whether the SNES has an NPC or not

5528:   Level: developer

5530: .seealso: SNESSetNPC(), SNESGetNPC()
5531: @*/
5532: PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
5533: {
5536:   *has_npc = (PetscBool) (snes->npc ? PETSC_TRUE : PETSC_FALSE);
5537:   return(0);
5538: }

5540: /*@
5541:     SNESSetNPCSide - Sets the preconditioning side.

5543:     Logically Collective on SNES

5545:     Input Parameter:
5546: .   snes - iterative context obtained from SNESCreate()

5548:     Output Parameter:
5549: .   side - the preconditioning side, where side is one of
5550: .vb
5551:       PC_LEFT - left preconditioning
5552:       PC_RIGHT - right preconditioning (default for most nonlinear solvers)
5553: .ve

5555:     Options Database Keys:
5556: .   -snes_pc_side <right,left>

5558:     Notes:
5559:     SNESNRICHARDSON and SNESNCG only support left preconditioning.

5561:     Level: intermediate

5563: .seealso: SNESGetNPCSide(), KSPSetPCSide()
5564: @*/
5565: PetscErrorCode  SNESSetNPCSide(SNES snes,PCSide side)
5566: {
5570:   snes->npcside= side;
5571:   return(0);
5572: }

5574: /*@
5575:     SNESGetNPCSide - Gets the preconditioning side.

5577:     Not Collective

5579:     Input Parameter:
5580: .   snes - iterative context obtained from SNESCreate()

5582:     Output Parameter:
5583: .   side - the preconditioning side, where side is one of
5584: .vb
5585:       PC_LEFT - left preconditioning
5586:       PC_RIGHT - right preconditioning (default for most nonlinear solvers)
5587: .ve

5589:     Level: intermediate

5591: .seealso: SNESSetNPCSide(), KSPGetPCSide()
5592: @*/
5593: PetscErrorCode  SNESGetNPCSide(SNES snes,PCSide *side)
5594: {
5598:   *side = snes->npcside;
5599:   return(0);
5600: }

5602: /*@
5603:   SNESSetLineSearch - Sets the linesearch on the SNES instance.

5605:   Collective on SNES

5607:   Input Parameters:
5608: + snes - iterative context obtained from SNESCreate()
5609: - linesearch   - the linesearch object

5611:   Notes:
5612:   Use SNESGetLineSearch() to retrieve the preconditioner context (for example,
5613:   to configure it using the API).

5615:   Level: developer

5617: .seealso: SNESGetLineSearch()
5618: @*/
5619: PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
5620: {

5627:   PetscObjectReference((PetscObject) linesearch);
5628:   SNESLineSearchDestroy(&snes->linesearch);

5630:   snes->linesearch = linesearch;

5632:   PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);
5633:   return(0);
5634: }

5636: /*@
5637:   SNESGetLineSearch - Returns a pointer to the line search context set with SNESSetLineSearch()
5638:   or creates a default line search instance associated with the SNES and returns it.

5640:   Not Collective

5642:   Input Parameter:
5643: . snes - iterative context obtained from SNESCreate()

5645:   Output Parameter:
5646: . linesearch - linesearch context

5648:   Level: beginner

5650: .seealso: SNESSetLineSearch(), SNESLineSearchCreate()
5651: @*/
5652: PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
5653: {
5655:   const char     *optionsprefix;

5660:   if (!snes->linesearch) {
5661:     SNESGetOptionsPrefix(snes, &optionsprefix);
5662:     SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch);
5663:     SNESLineSearchSetSNES(snes->linesearch, snes);
5664:     SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix);
5665:     PetscObjectIncrementTabLevel((PetscObject) snes->linesearch, (PetscObject) snes, 1);
5666:     PetscLogObjectParent((PetscObject)snes, (PetscObject)snes->linesearch);
5667:   }
5668:   *linesearch = snes->linesearch;
5669:   return(0);
5670: }