Actual source code: itcreate.c
petsc-3.7.1 2016-05-15
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      2: /*
      3:      The basic KSP routines, Create, View etc. are here.
      4: */
      5: #include <petsc/private/kspimpl.h>      /*I "petscksp.h" I*/

      7: /* Logging support */
      8: PetscClassId  KSP_CLASSID;
      9: PetscClassId  DMKSP_CLASSID;
     10: PetscLogEvent KSP_GMRESOrthogonalization, KSP_SetUp, KSP_Solve;

     12: /*
     13:    Contains the list of registered KSP routines
     14: */
     15: PetscFunctionList KSPList              = 0;
     16: PetscBool         KSPRegisterAllCalled = PETSC_FALSE;

     20: /*@C
     21:   KSPLoad - Loads a KSP that has been stored in binary  with KSPView().

     23:   Collective on PetscViewer

     25:   Input Parameters:
     26: + newdm - the newly loaded KSP, this needs to have been created with KSPCreate() or
     27:            some related function before a call to KSPLoad().
     28: - viewer - binary file viewer, obtained from PetscViewerBinaryOpen()

     30:    Level: intermediate

     32:   Notes:
     33:    The type is determined by the data in the file, any type set into the KSP before this call is ignored.

     35:   Notes for advanced users:
     36:   Most users should not need to know the details of the binary storage
     37:   format, since KSPLoad() and KSPView() completely hide these details.
     38:   But for anyone who's interested, the standard binary matrix storage
     39:   format is
     40: .vb
     41:      has not yet been determined
     42: .ve

     44: .seealso: PetscViewerBinaryOpen(), KSPView(), MatLoad(), VecLoad()
     45: @*/
     46: PetscErrorCode  KSPLoad(KSP newdm, PetscViewer viewer)
     47: {
     49:   PetscBool      isbinary;
     50:   PetscInt       classid;
     51:   char           type[256];
     52:   PC             pc;

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

     60:   PetscViewerBinaryRead(viewer,&classid,1,NULL,PETSC_INT);
     61:   if (classid != KSP_FILE_CLASSID) SETERRQ(PetscObjectComm((PetscObject)newdm),PETSC_ERR_ARG_WRONG,"Not KSP next in file");
     62:   PetscViewerBinaryRead(viewer,type,256,NULL,PETSC_CHAR);
     63:   KSPSetType(newdm, type);
     64:   if (newdm->ops->load) {
     65:     (*newdm->ops->load)(newdm,viewer);
     66:   }
     67:   KSPGetPC(newdm,&pc);
     68:   PCLoad(pc,viewer);
     69:   return(0);
     70: }

     72: #include <petscdraw.h>
     73: #if defined(PETSC_HAVE_SAWS)
     74: #include <petscviewersaws.h>
     75: #endif
     78: /*@C
     79:    KSPView - Prints the KSP data structure.

     81:    Collective on KSP

     83:    Input Parameters:
     84: +  ksp - the Krylov space context
     85: -  viewer - visualization context

     87:    Options Database Keys:
     88: .  -ksp_view - print the ksp data structure at the end of a KSPSolve call

     90:    Note:
     91:    The available visualization contexts include
     92: +     PETSC_VIEWER_STDOUT_SELF - standard output (default)
     93: -     PETSC_VIEWER_STDOUT_WORLD - synchronized standard
     94:          output where only the first processor opens
     95:          the file.  All other processors send their
     96:          data to the first processor to print.

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

    101:    Level: beginner

    103: .keywords: KSP, view

    105: .seealso: PCView(), PetscViewerASCIIOpen()
    106: @*/
    107: PetscErrorCode  KSPView(KSP ksp,PetscViewer viewer)
    108: {
    110:   PetscBool      iascii,isbinary,isdraw;
    111: #if defined(PETSC_HAVE_SAWS)
    112:   PetscBool      issaws;
    113: #endif

    117:   if (!viewer) {
    118:     PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)ksp),&viewer);
    119:   }

    123:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
    124:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERBINARY,&isbinary);
    125:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERDRAW,&isdraw);
    126: #if defined(PETSC_HAVE_SAWS)
    127:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSAWS,&issaws);
    128: #endif
    129:   if (iascii) {
    130:     PetscObjectPrintClassNamePrefixType((PetscObject)ksp,viewer);
    131:     if (ksp->ops->view) {
    132:       PetscViewerASCIIPushTab(viewer);
    133:       (*ksp->ops->view)(ksp,viewer);
    134:       PetscViewerASCIIPopTab(viewer);
    135:     }
    136:     if (ksp->guess_zero) {
    137:       PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D, initial guess is zero\n",ksp->max_it);
    138:     } else {
    139:       PetscViewerASCIIPrintf(viewer,"  maximum iterations=%D\n", ksp->max_it);
    140:     }
    141:     if (ksp->guess_knoll) {PetscViewerASCIIPrintf(viewer,"  using preconditioner applied to right hand side for initial guess\n");}
    142:     PetscViewerASCIIPrintf(viewer,"  tolerances:  relative=%g, absolute=%g, divergence=%g\n",(double)ksp->rtol,(double)ksp->abstol,(double)ksp->divtol);
    143:     if (ksp->pc_side == PC_RIGHT) {
    144:       PetscViewerASCIIPrintf(viewer,"  right preconditioning\n");
    145:     } else if (ksp->pc_side == PC_SYMMETRIC) {
    146:       PetscViewerASCIIPrintf(viewer,"  symmetric preconditioning\n");
    147:     } else {
    148:       PetscViewerASCIIPrintf(viewer,"  left preconditioning\n");
    149:     }
    150:     if (ksp->guess) {PetscViewerASCIIPrintf(viewer,"  using Fischers initial guess method %D with size %D\n",ksp->guess->method,ksp->guess->maxl);}
    151:     if (ksp->dscale) {PetscViewerASCIIPrintf(viewer,"  diagonally scaled system\n");}
    152:     if (!ksp->guess_zero) {PetscViewerASCIIPrintf(viewer,"  using nonzero initial guess\n");}
    153:     PetscViewerASCIIPrintf(viewer,"  using %s norm type for convergence test\n",KSPNormTypes[ksp->normtype]);
    154:   } else if (isbinary) {
    155:     PetscInt    classid = KSP_FILE_CLASSID;
    156:     MPI_Comm    comm;
    157:     PetscMPIInt rank;
    158:     char        type[256];

    160:     PetscObjectGetComm((PetscObject)ksp,&comm);
    161:     MPI_Comm_rank(comm,&rank);
    162:     if (!rank) {
    163:       PetscViewerBinaryWrite(viewer,&classid,1,PETSC_INT,PETSC_FALSE);
    164:       PetscStrncpy(type,((PetscObject)ksp)->type_name,256);
    165:       PetscViewerBinaryWrite(viewer,type,256,PETSC_CHAR,PETSC_FALSE);
    166:     }
    167:     if (ksp->ops->view) {
    168:       (*ksp->ops->view)(ksp,viewer);
    169:     }
    170:   } else if (isdraw) {
    171:     PetscDraw draw;
    172:     char      str[36];
    173:     PetscReal x,y,bottom,h;
    174:     PetscBool flg;

    176:     PetscViewerDrawGetDraw(viewer,0,&draw);
    177:     PetscDrawGetCurrentPoint(draw,&x,&y);
    178:     PetscObjectTypeCompare((PetscObject)ksp,KSPPREONLY,&flg);
    179:     if (!flg) {
    180:       PetscStrcpy(str,"KSP: ");
    181:       PetscStrcat(str,((PetscObject)ksp)->type_name);
    182:       PetscDrawStringBoxed(draw,x,y,PETSC_DRAW_RED,PETSC_DRAW_BLACK,str,NULL,&h);
    183:       bottom = y - h;
    184:     } else {
    185:       bottom = y;
    186:     }
    187:     PetscDrawPushCurrentPoint(draw,x,bottom);
    188: #if defined(PETSC_HAVE_SAWS)
    189:   } else if (issaws) {
    190:     PetscMPIInt rank;
    191:     const char  *name;

    193:     PetscObjectGetName((PetscObject)ksp,&name);
    194:     MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
    195:     if (!((PetscObject)ksp)->amsmem && !rank) {
    196:       char       dir[1024];

    198:       PetscObjectViewSAWs((PetscObject)ksp,viewer);
    199:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/its",name);
    200:       PetscStackCallSAWs(SAWs_Register,(dir,&ksp->its,1,SAWs_READ,SAWs_INT));
    201:       if (!ksp->res_hist) {
    202:         KSPSetResidualHistory(ksp,NULL,PETSC_DECIDE,PETSC_TRUE);
    203:       }
    204:       PetscSNPrintf(dir,1024,"/PETSc/Objects/%s/res_hist",name);
    205:       PetscStackCallSAWs(SAWs_Register,(dir,ksp->res_hist,10,SAWs_READ,SAWs_DOUBLE));
    206:     }
    207: #endif
    208:   } else if (ksp->ops->view) {
    209:     (*ksp->ops->view)(ksp,viewer);
    210:   }
    211:   if (!ksp->skippcsetfromoptions) {
    212:     if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    213:     PCView(ksp->pc,viewer);
    214:   }
    215:   if (isdraw) {
    216:     PetscDraw draw;
    217:     PetscViewerDrawGetDraw(viewer,0,&draw);
    218:     PetscDrawPopCurrentPoint(draw);
    219:   }
    220:   return(0);
    221: }

    226: /*@
    227:    KSPSetNormType - Sets the norm that is used for convergence testing.

    229:    Logically Collective on KSP

    231:    Input Parameter:
    232: +  ksp - Krylov solver context
    233: -  normtype - one of
    234: $   KSP_NORM_NONE - skips computing the norm, this should only be used if you are using
    235: $                 the Krylov method as a smoother with a fixed small number of iterations.
    236: $                 Implicitly sets KSPConvergedSkip as KSP convergence test.
    237: $   KSP_NORM_PRECONDITIONED - the default for left preconditioned solves, uses the l2 norm
    238: $                 of the preconditioned residual P^{-1}(b - A x)
    239: $   KSP_NORM_UNPRECONDITIONED - uses the l2 norm of the true b - Ax residual.
    240: $   KSP_NORM_NATURAL - supported  by KSPCG, KSPCR, KSPCGNE, KSPCGS

    243:    Options Database Key:
    244: .   -ksp_norm_type <none,preconditioned,unpreconditioned,natural>

    246:    Notes:
    247:    Not all combinations of preconditioner side (see KSPSetPCSide()) and norm type are supported by all Krylov methods.
    248:    If only one is set, PETSc tries to automatically change the other to find a compatible pair.  If no such combination
    249:    is supported, PETSc will generate an error.

    251:    Developer Notes:
    252:    Supported combinations of norm and preconditioner side are set using KSPSetSupportedNorm().

    255:    Level: advanced

    257: .keywords: KSP, create, context, norms

    259: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetCheckNormIteration(), KSPSetPCSide(), KSPGetPCSide()
    260: @*/
    261: PetscErrorCode  KSPSetNormType(KSP ksp,KSPNormType normtype)
    262: {

    268:   ksp->normtype = ksp->normtype_set = normtype;
    269:   if (normtype == KSP_NORM_NONE) {
    270:     KSPSetConvergenceTest(ksp,KSPConvergedSkip,0,0);
    271:     PetscInfo(ksp,"Warning: setting KSPNormType to skip computing the norm\n\
    272:  KSP convergence test is implicitly set to KSPConvergedSkip\n");
    273:   }
    274:   return(0);
    275: }

    279: /*@
    280:    KSPSetCheckNormIteration - Sets the first iteration at which the norm of the residual will be
    281:      computed and used in the convergence test.

    283:    Logically Collective on KSP

    285:    Input Parameter:
    286: +  ksp - Krylov solver context
    287: -  it  - use -1 to check at all iterations

    289:    Notes:
    290:    Currently only works with KSPCG, KSPBCGS and KSPIBCGS

    292:    Use KSPSetNormType(ksp,KSP_NORM_NONE) to never check the norm

    294:    On steps where the norm is not computed, the previous norm is still in the variable, so if you run with, for example,
    295:     -ksp_monitor the residual norm will appear to be unchanged for several iterations (though it is not really unchanged).
    296:    Level: advanced

    298: .keywords: KSP, create, context, norms

    300: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType()
    301: @*/
    302: PetscErrorCode  KSPSetCheckNormIteration(KSP ksp,PetscInt it)
    303: {
    307:   ksp->chknorm = it;
    308:   return(0);
    309: }

    313: /*@
    314:    KSPSetLagNorm - Lags the residual norm calculation so that it is computed as part of the MPI_Allreduce() for
    315:    computing the inner products for the next iteration.  This can reduce communication costs at the expense of doing
    316:    one additional iteration.

    319:    Logically Collective on KSP

    321:    Input Parameter:
    322: +  ksp - Krylov solver context
    323: -  flg - PETSC_TRUE or PETSC_FALSE

    325:    Options Database Keys:
    326: .  -ksp_lag_norm - lag the calculated residual norm

    328:    Notes:
    329:    Currently only works with KSPIBCGS.

    331:    Use KSPSetNormType(ksp,KSP_NORM_NONE) to never check the norm

    333:    If you lag the norm and run with, for example, -ksp_monitor, the residual norm reported will be the lagged one.
    334:    Level: advanced

    336: .keywords: KSP, create, context, norms

    338: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSPConvergedSkip(), KSPSetNormType(), KSPSetCheckNormIteration()
    339: @*/
    340: PetscErrorCode  KSPSetLagNorm(KSP ksp,PetscBool flg)
    341: {
    345:   ksp->lagnorm = flg;
    346:   return(0);
    347: }

    351: /*@
    352:    KSPSetSupportedNorm - Sets a norm and preconditioner side supported by a KSP

    354:    Logically Collective

    356:    Input Arguments:
    357: +  ksp - Krylov method
    358: .  normtype - supported norm type
    359: .  pcside - preconditioner side that can be used with this norm
    360: -  preference - integer preference for this combination, larger values have higher priority

    362:    Level: developer

    364:    Notes:
    365:    This function should be called from the implementation files KSPCreate_XXX() to declare
    366:    which norms and preconditioner sides are supported. Users should not need to call this
    367:    function.

    369:    KSP_NORM_NONE is supported by default with all KSP methods and any PC side at priority 1.  If a KSP explicitly does
    370:    not support KSP_NORM_NONE, it should set this by setting priority=0.  Since defaulting to KSP_NORM_NONE is usually
    371:    undesirable, more desirable norms should usually have priority 2 or higher.

    373: .seealso: KSPSetNormType(), KSPSetPCSide()
    374: @*/
    375: PetscErrorCode KSPSetSupportedNorm(KSP ksp,KSPNormType normtype,PCSide pcside,PetscInt priority)
    376: {

    380:   ksp->normsupporttable[normtype][pcside] = priority;
    381:   return(0);
    382: }

    386: PetscErrorCode KSPNormSupportTableReset_Private(KSP ksp)
    387: {

    391:   PetscMemzero(ksp->normsupporttable,sizeof(ksp->normsupporttable));
    392:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_LEFT,1);
    393:   KSPSetSupportedNorm(ksp,KSP_NORM_NONE,PC_RIGHT,1);
    394:   ksp->pc_side  = ksp->pc_side_set;
    395:   ksp->normtype = ksp->normtype_set;
    396:   return(0);
    397: }

    401: PetscErrorCode KSPSetUpNorms_Private(KSP ksp,KSPNormType *normtype,PCSide *pcside)
    402: {
    403:   PetscInt i,j,best,ibest = 0,jbest = 0;

    406:   best = 0;
    407:   for (i=0; i<KSP_NORM_MAX; i++) {
    408:     for (j=0; j<PC_SIDE_MAX; j++) {
    409:       if ((ksp->normtype == KSP_NORM_DEFAULT || ksp->normtype == i)
    410:           && (ksp->pc_side == PC_SIDE_DEFAULT || ksp->pc_side == j)
    411:           && (ksp->normsupporttable[i][j] > best)) {
    412:         best  = ksp->normsupporttable[i][j];
    413:         ibest = i;
    414:         jbest = j;
    415:       }
    416:     }
    417:   }
    418:   if (best < 1) {
    419:     if (ksp->normtype == KSP_NORM_DEFAULT && ksp->pc_side == PC_SIDE_DEFAULT) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_PLIB,"The %s KSP implementation did not call KSPSetSupportedNorm()",((PetscObject)ksp)->type_name);
    420:     if (ksp->normtype == KSP_NORM_DEFAULT) SETERRQ2(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"KSP %s does not support %s",((PetscObject)ksp)->type_name,PCSides[ksp->pc_side]);
    421:     if (ksp->pc_side == PC_SIDE_DEFAULT) SETERRQ2(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"KSP %s does not support %s",((PetscObject)ksp)->type_name,KSPNormTypes[ksp->normtype]);
    422:     SETERRQ3(PetscObjectComm((PetscObject)ksp),PETSC_ERR_SUP,"KSP %s does not support %s with %s",((PetscObject)ksp)->type_name,KSPNormTypes[ksp->normtype],PCSides[ksp->pc_side]);
    423:   }
    424:   *normtype = (KSPNormType)ibest;
    425:   *pcside   = (PCSide)jbest;
    426:   return(0);
    427: }

    431: /*@
    432:    KSPGetNormType - Gets the norm that is used for convergence testing.

    434:    Not Collective

    436:    Input Parameter:
    437: .  ksp - Krylov solver context

    439:    Output Parameter:
    440: .  normtype - norm that is used for convergence testing

    442:    Level: advanced

    444: .keywords: KSP, create, context, norms

    446: .seealso: KSPNormType, KSPSetNormType(), KSPConvergedSkip()
    447: @*/
    448: PetscErrorCode  KSPGetNormType(KSP ksp, KSPNormType *normtype)
    449: {

    455:   KSPSetUpNorms_Private(ksp,&ksp->normtype,&ksp->pc_side);
    456:   *normtype = ksp->normtype;
    457:   return(0);
    458: }

    460: #if defined(PETSC_HAVE_SAWS)
    461: #include <petscviewersaws.h>
    462: #endif

    466: /*@
    467:    KSPSetOperators - Sets the matrix associated with the linear system
    468:    and a (possibly) different one associated with the preconditioner.

    470:    Collective on KSP and Mat

    472:    Input Parameters:
    473: +  ksp - the KSP context
    474: .  Amat - the matrix that defines the linear system
    475: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

    477:    Notes:

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

    482:     All future calls to KSPSetOperators() must use the same size matrices!

    484:     Passing a NULL for Amat or Pmat removes the matrix that is currently used.

    486:     If you wish to replace either Amat or Pmat but leave the other one untouched then
    487:     first call KSPGetOperators() to get the one you wish to keep, call PetscObjectReference()
    488:     on it and then pass it back in in your call to KSPSetOperators().

    490:     Level: beginner

    492:    Alternative usage: If the operators have NOT been set with KSP/PCSetOperators() then the operators
    493:       are created in PC and returned to the user. In this case, if both operators
    494:       mat and pmat are requested, two DIFFERENT operators will be returned. If
    495:       only one is requested both operators in the PC will be the same (i.e. as
    496:       if one had called KSP/PCSetOperators() with the same argument for both Mats).
    497:       The user must set the sizes of the returned matrices and their type etc just
    498:       as if the user created them with MatCreate(). For example,

    500: $         KSP/PCGetOperators(ksp/pc,&mat,NULL); is equivalent to
    501: $           set size, type, etc of mat

    503: $         MatCreate(comm,&mat);
    504: $         KSP/PCSetOperators(ksp/pc,mat,mat);
    505: $         PetscObjectDereference((PetscObject)mat);
    506: $           set size, type, etc of mat

    508:      and

    510: $         KSP/PCGetOperators(ksp/pc,&mat,&pmat); is equivalent to
    511: $           set size, type, etc of mat and pmat

    513: $         MatCreate(comm,&mat);
    514: $         MatCreate(comm,&pmat);
    515: $         KSP/PCSetOperators(ksp/pc,mat,pmat);
    516: $         PetscObjectDereference((PetscObject)mat);
    517: $         PetscObjectDereference((PetscObject)pmat);
    518: $           set size, type, etc of mat and pmat

    520:     The rational for this support is so that when creating a TS, SNES, or KSP the hierarchy
    521:     of underlying objects (i.e. SNES, KSP, PC, Mat) and their livespans can be completely
    522:     managed by the top most level object (i.e. the TS, SNES, or KSP). Another way to look
    523:     at this is when you create a SNES you do not NEED to create a KSP and attach it to
    524:     the SNES object (the SNES object manages it for you). Similarly when you create a KSP
    525:     you do not need to attach a PC to it (the KSP object manages the PC object for you).
    526:     Thus, why should YOU have to create the Mat and attach it to the SNES/KSP/PC, when
    527:     it can be created for you?

    529: .keywords: KSP, set, operators, matrix, preconditioner, linear system

    531: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPGetOperators(), KSPSetComputeOperators(), KSPSetComputeInitialGuess(), KSPSetComputeRHS()
    532: @*/
    533: PetscErrorCode  KSPSetOperators(KSP ksp,Mat Amat,Mat Pmat)
    534: {

    543:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    544:   PCSetOperators(ksp->pc,Amat,Pmat);
    545:   if (ksp->setupstage == KSP_SETUP_NEWRHS) ksp->setupstage = KSP_SETUP_NEWMATRIX;  /* so that next solve call will call PCSetUp() on new matrix */
    546:   if (ksp->guess) {
    547:     KSPFischerGuessReset(ksp->guess);
    548:   }
    549:   return(0);
    550: }

    554: /*@
    555:    KSPGetOperators - Gets the matrix associated with the linear system
    556:    and a (possibly) different one associated with the preconditioner.

    558:    Collective on KSP and Mat

    560:    Input Parameter:
    561: .  ksp - the KSP context

    563:    Output Parameters:
    564: +  Amat - the matrix that defines the linear system
    565: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as Amat.

    567:     Level: intermediate

    569:    Notes: DOES NOT increase the reference counts of the matrix, so you should NOT destroy them.

    571: .keywords: KSP, set, get, operators, matrix, preconditioner, linear system

    573: .seealso: KSPSolve(), KSPGetPC(), PCGetOperators(), PCSetOperators(), KSPSetOperators(), KSPGetOperatorsSet()
    574: @*/
    575: PetscErrorCode  KSPGetOperators(KSP ksp,Mat *Amat,Mat *Pmat)
    576: {

    581:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    582:   PCGetOperators(ksp->pc,Amat,Pmat);
    583:   return(0);
    584: }

    588: /*@C
    589:    KSPGetOperatorsSet - Determines if the matrix associated with the linear system and
    590:    possibly a different one associated with the preconditioner have been set in the KSP.

    592:    Not collective, though the results on all processes should be the same

    594:    Input Parameter:
    595: .  pc - the KSP context

    597:    Output Parameters:
    598: +  mat - the matrix associated with the linear system was set
    599: -  pmat - matrix associated with the preconditioner was set, usually the same

    601:    Level: intermediate

    603: .keywords: KSP, get, operators, matrix, linear system

    605: .seealso: PCSetOperators(), KSPGetOperators(), KSPSetOperators(), PCGetOperators(), PCGetOperatorsSet()
    606: @*/
    607: PetscErrorCode  KSPGetOperatorsSet(KSP ksp,PetscBool  *mat,PetscBool  *pmat)
    608: {

    613:   if (!ksp->pc) {KSPGetPC(ksp,&ksp->pc);}
    614:   PCGetOperatorsSet(ksp->pc,mat,pmat);
    615:   return(0);
    616: }

    620: /*@C
    621:    KSPSetPreSolve - Sets a function that is called before every KSPSolve() is started

    623:    Logically Collective on KSP

    625:    Input Parameters:
    626: +   ksp - the solver object
    627: .   presolve - the function to call before the solve
    628: -   prectx - any context needed by the function

    630:    Level: developer

    632: .keywords: KSP, create, context

    634: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPostSolve()
    635: @*/
    636: PetscErrorCode  KSPSetPreSolve(KSP ksp,PetscErrorCode (*presolve)(KSP,Vec,Vec,void*),void *prectx)
    637: {
    640:   ksp->presolve = presolve;
    641:   ksp->prectx   = prectx;
    642:   return(0);
    643: }

    647: /*@C
    648:    KSPSetPostSolve - Sets a function that is called after every KSPSolve() completes (whether it converges or not)

    650:    Logically Collective on KSP

    652:    Input Parameters:
    653: +   ksp - the solver object
    654: .   postsolve - the function to call after the solve
    655: -   postctx - any context needed by the function

    657:    Level: developer

    659: .keywords: KSP, create, context

    661: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP, KSPSetPreSolve()
    662: @*/
    663: PetscErrorCode  KSPSetPostSolve(KSP ksp,PetscErrorCode (*postsolve)(KSP,Vec,Vec,void*),void *postctx)
    664: {
    667:   ksp->postsolve = postsolve;
    668:   ksp->postctx   = postctx;
    669:   return(0);
    670: }

    674: /*@
    675:    KSPCreate - Creates the default KSP context.

    677:    Collective on MPI_Comm

    679:    Input Parameter:
    680: .  comm - MPI communicator

    682:    Output Parameter:
    683: .  ksp - location to put the KSP context

    685:    Notes:
    686:    The default KSP type is GMRES with a restart of 30, using modified Gram-Schmidt
    687:    orthogonalization.

    689:    Level: beginner

    691: .keywords: KSP, create, context

    693: .seealso: KSPSetUp(), KSPSolve(), KSPDestroy(), KSP
    694: @*/
    695: PetscErrorCode  KSPCreate(MPI_Comm comm,KSP *inksp)
    696: {
    697:   KSP            ksp;
    699:   void           *ctx;

    703:   *inksp = 0;
    704:   KSPInitializePackage();

    706:   PetscHeaderCreate(ksp,KSP_CLASSID,"KSP","Krylov Method","KSP",comm,KSPDestroy,KSPView);

    708:   ksp->max_it  = 10000;
    709:   ksp->pc_side = ksp->pc_side_set = PC_SIDE_DEFAULT;
    710:   ksp->rtol    = 1.e-5;
    711: #if defined(PETSC_USE_REAL_SINGLE)
    712:   ksp->abstol  = 1.e-25;
    713: #else
    714:   ksp->abstol  = 1.e-50;
    715: #endif
    716:   ksp->divtol  = 1.e4;

    718:   ksp->chknorm        = -1;
    719:   ksp->normtype       = ksp->normtype_set = KSP_NORM_DEFAULT;
    720:   ksp->rnorm          = 0.0;
    721:   ksp->its            = 0;
    722:   ksp->guess_zero     = PETSC_TRUE;
    723:   ksp->calc_sings     = PETSC_FALSE;
    724:   ksp->res_hist       = NULL;
    725:   ksp->res_hist_alloc = NULL;
    726:   ksp->res_hist_len   = 0;
    727:   ksp->res_hist_max   = 0;
    728:   ksp->res_hist_reset = PETSC_TRUE;
    729:   ksp->numbermonitors = 0;

    731:   KSPConvergedDefaultCreate(&ctx);
    732:   KSPSetConvergenceTest(ksp,KSPConvergedDefault,ctx,KSPConvergedDefaultDestroy);
    733:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
    734:   ksp->ops->buildresidual = KSPBuildResidualDefault;

    736:   ksp->vec_sol    = 0;
    737:   ksp->vec_rhs    = 0;
    738:   ksp->pc         = 0;
    739:   ksp->data       = 0;
    740:   ksp->nwork      = 0;
    741:   ksp->work       = 0;
    742:   ksp->reason     = KSP_CONVERGED_ITERATING;
    743:   ksp->setupstage = KSP_SETUP_NEW;

    745:   KSPNormSupportTableReset_Private(ksp);

    747:   *inksp = ksp;
    748:   return(0);
    749: }

    753: /*@C
    754:    KSPSetType - Builds KSP for a particular solver.

    756:    Logically Collective on KSP

    758:    Input Parameters:
    759: +  ksp      - the Krylov space context
    760: -  type - a known method

    762:    Options Database Key:
    763: .  -ksp_type  <method> - Sets the method; use -help for a list
    764:     of available methods (for instance, cg or gmres)

    766:    Notes:
    767:    See "petsc/include/petscksp.h" for available methods (for instance,
    768:    KSPCG or KSPGMRES).

    770:   Normally, it is best to use the KSPSetFromOptions() command and
    771:   then set the KSP type from the options database rather than by using
    772:   this routine.  Using the options database provides the user with
    773:   maximum flexibility in evaluating the many different Krylov methods.
    774:   The KSPSetType() routine is provided for those situations where it
    775:   is necessary to set the iterative solver independently of the command
    776:   line or options database.  This might be the case, for example, when
    777:   the choice of iterative solver changes during the execution of the
    778:   program, and the user's application is taking responsibility for
    779:   choosing the appropriate method.  In other words, this routine is
    780:   not for beginners.

    782:   Level: intermediate

    784:   Developer Note: KSPRegister() is used to add Krylov types to KSPList from which they
    785:   are accessed by KSPSetType().

    787: .keywords: KSP, set, method

    789: .seealso: PCSetType(), KSPType, KSPRegister(), KSPCreate()

    791: @*/
    792: PetscErrorCode  KSPSetType(KSP ksp, KSPType type)
    793: {
    794:   PetscErrorCode ierr,(*r)(KSP);
    795:   PetscBool      match;

    801:   PetscObjectTypeCompare((PetscObject)ksp,type,&match);
    802:   if (match) return(0);

    804:    PetscFunctionListFind(KSPList,type,&r);
    805:   if (!r) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_UNKNOWN_TYPE,"Unable to find requested KSP type %s",type);
    806:   /* Destroy the previous private KSP context */
    807:   if (ksp->ops->destroy) {
    808:     (*ksp->ops->destroy)(ksp);
    809:     ksp->ops->destroy = NULL;
    810:   }
    811:   /* Reinitialize function pointers in KSPOps structure */
    812:   PetscMemzero(ksp->ops,sizeof(struct _KSPOps));
    813:   ksp->ops->buildsolution = KSPBuildSolutionDefault;
    814:   ksp->ops->buildresidual = KSPBuildResidualDefault;
    815:   KSPNormSupportTableReset_Private(ksp);
    816:   /* Call the KSPCreate_XXX routine for this particular Krylov solver */
    817:   ksp->setupstage = KSP_SETUP_NEW;
    818:   PetscObjectChangeTypeName((PetscObject)ksp,type);
    819:   (*r)(ksp);
    820:   return(0);
    821: }

    825: /*@C
    826:    KSPGetType - Gets the KSP type as a string from the KSP object.

    828:    Not Collective

    830:    Input Parameter:
    831: .  ksp - Krylov context

    833:    Output Parameter:
    834: .  name - name of KSP method

    836:    Level: intermediate

    838: .keywords: KSP, get, method, name

    840: .seealso: KSPSetType()
    841: @*/
    842: PetscErrorCode  KSPGetType(KSP ksp,KSPType *type)
    843: {
    847:   *type = ((PetscObject)ksp)->type_name;
    848:   return(0);
    849: }

    853: /*@C
    854:   KSPRegister -  Adds a method to the Krylov subspace solver package.

    856:    Not Collective

    858:    Input Parameters:
    859: +  name_solver - name of a new user-defined solver
    860: -  routine_create - routine to create method context

    862:    Notes:
    863:    KSPRegister() may be called multiple times to add several user-defined solvers.

    865:    Sample usage:
    866: .vb
    867:    KSPRegister("my_solver",MySolverCreate);
    868: .ve

    870:    Then, your solver can be chosen with the procedural interface via
    871: $     KSPSetType(ksp,"my_solver")
    872:    or at runtime via the option
    873: $     -ksp_type my_solver

    875:    Level: advanced

    877: .keywords: KSP, register

    879: .seealso: KSPRegisterAll(), KSPRegisterDestroy()

    881: @*/
    882: PetscErrorCode  KSPRegister(const char sname[],PetscErrorCode (*function)(KSP))
    883: {

    887:   PetscFunctionListAdd(&KSPList,sname,function);
    888:   return(0);
    889: }