Actual source code: pod.c
petsc-3.9.2 2018-05-20
1: #include <petsc/private/kspimpl.h>
2: #include <petsc/private/matimpl.h>
3: #include <petscblaslapack.h>
4: static PetscBool cited = PETSC_FALSE;
5: static const char citation[] =
6: "@phdthesis{zampini2010non,\n"
7: " title={Non-overlapping Domain Decomposition Methods for Cardiac Reaction-Diffusion Models and Applications},\n"
8: " author={Zampini, S},\n"
9: " year={2010},\n"
10: " school={PhD thesis, Universita degli Studi di Milano}\n"
11: "}\n";
13: typedef struct {
14: PetscInt maxn; /* maximum number of snapshots */
15: PetscInt n; /* number of active snapshots */
16: PetscInt curr; /* current tip of snapshots set */
17: Vec *xsnap; /* snapshots */
18: Vec *bsnap; /* rhs snapshots */
19: PetscScalar *dots_iallreduce;
20: MPI_Request req_iallreduce;
21: PetscInt ndots_iallreduce; /* if we have iallreduce we can hide the VecMDot communications */
22: PetscReal tol; /* relative tolerance to retain eigenvalues */
23: PetscBool Aspd; /* if true, uses the SPD operator as inner product */
24: PetscScalar *corr; /* correlation matrix */
25: PetscReal *eigs; /* eigenvalues */
26: PetscScalar *eigv; /* eigenvectors */
27: PetscBLASInt nen; /* dimension of lower dimensional system */
28: PetscInt st; /* first eigenvector of correlation matrix to be retained */
29: PetscBLASInt *iwork; /* integer work vector */
30: PetscScalar *yhay; /* Y^H * A * Y */
31: PetscScalar *low; /* lower dimensional linear system */
32: #if defined(PETSC_USE_COMPLEX)
33: PetscReal *rwork;
34: #endif
35: PetscBLASInt lwork;
36: PetscScalar *swork;
37: PetscBool monitor;
38: } KSPGuessPOD;
40: static PetscErrorCode KSPGuessReset_POD(KSPGuess guess)
41: {
42: KSPGuessPOD *pod = (KSPGuessPOD*)guess->data;
44: PetscLayout Alay = NULL,vlay = NULL;
45: PetscBool cong;
48: pod->n = 0;
49: pod->curr = 0;
50: /* need to wait for completion of outstanding requests */
51: if (pod->ndots_iallreduce) {
52: MPI_Wait(&pod->req_iallreduce,MPI_STATUS_IGNORE);
53: }
54: pod->ndots_iallreduce = 0;
55: /* destroy vectors if the size of the linear system has changed */
56: if (guess->A) {
57: MatGetLayouts(guess->A,&Alay,NULL);
58: }
59: if (pod->xsnap) {
60: VecGetLayout(pod->xsnap[0],&vlay);
61: }
62: cong = PETSC_FALSE;
63: if (vlay && Alay) {
64: PetscLayoutCompare(Alay,vlay,&cong);
65: }
66: if (!cong) {
67: VecDestroyVecs(pod->maxn,&pod->xsnap);
68: VecDestroyVecs(pod->maxn,&pod->bsnap);
69: }
70: return(0);
71: }
73: static PetscErrorCode KSPGuessSetUp_POD(KSPGuess guess)
74: {
75: KSPGuessPOD *pod = (KSPGuessPOD*)guess->data;
79: if (!pod->corr) {
80: PetscScalar sdummy;
81: PetscReal rdummy = 0;
82: PetscBLASInt bN,lierr,idummy;
84: PetscCalloc6(pod->maxn*pod->maxn,&pod->corr,pod->maxn,&pod->eigs,pod->maxn*pod->maxn,&pod->eigv,
85: 6*pod->maxn,&pod->iwork,pod->maxn*pod->maxn,&pod->yhay,pod->maxn*pod->maxn,&pod->low);
86: #if defined(PETSC_USE_COMPLEX)
87: PetscMalloc1(7*pod->maxn,&pod->rwork);
88: #endif
89: #if defined(PETSC_HAVE_MPI_IALLREDUCE)
90: PetscMalloc1(3*pod->maxn,&pod->dots_iallreduce);
91: #endif
92: pod->lwork = -1;
93: PetscBLASIntCast(pod->maxn,&bN);
94: #if !defined(PETSC_USE_COMPLEX)
95: PetscStackCallBLAS("LAPACKsyevx",LAPACKsyevx_("V","A","L",&bN,pod->corr,&bN,&rdummy,&rdummy,&idummy,&idummy,
96: &rdummy,&idummy,pod->eigs,pod->eigv,&bN,&sdummy,&pod->lwork,pod->iwork,pod->iwork+5*bN,&lierr));
97: #else
98: PetscStackCallBLAS("LAPACKsyevx",LAPACKsyevx_("V","A","L",&bN,pod->corr,&bN,&rdummy,&rdummy,&idummy,&idummy,
99: &rdummy,&idummy,pod->eigs,pod->eigv,&bN,&sdummy,&pod->lwork,pod->rwork,pod->iwork,pod->iwork+5*bN,&lierr));
100: #endif
101: if (lierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in query to SYEV Lapack routine %d",(int)lierr);
102: PetscBLASIntCast((PetscInt)PetscRealPart(sdummy),&pod->lwork);
103: PetscMalloc1(pod->lwork+PetscMax(bN*bN,6*bN),&pod->swork);
104: }
105: /* work vectors are sequential, we explicitly use MPI_Allreduce */
106: if (!pod->xsnap) {
107: VecType type;
108: Vec *v,vseq;
109: PetscInt n;
111: KSPCreateVecs(guess->ksp,1,&v,0,NULL);
112: VecCreate(PETSC_COMM_SELF,&vseq);
113: VecGetLocalSize(v[0],&n);
114: VecSetSizes(vseq,n,n);
115: VecGetType(v[0],&type);
116: VecSetType(vseq,type);
117: VecDestroyVecs(1,&v);
118: VecDuplicateVecs(vseq,pod->maxn,&pod->xsnap);
119: VecDestroy(&vseq);
120: PetscLogObjectParents(guess,pod->maxn,pod->xsnap);
121: }
122: if (!pod->bsnap) {
123: VecDuplicateVecs(pod->xsnap[0],pod->maxn,&pod->bsnap);
124: PetscLogObjectParents(guess,pod->maxn,pod->bsnap);
125: }
126: return(0);
127: }
129: static PetscErrorCode KSPGuessDestroy_POD(KSPGuess guess)
130: {
131: KSPGuessPOD *pod = (KSPGuessPOD*)guess->data;
132: PetscErrorCode ierr;
135: PetscFree6(pod->corr,pod->eigs,pod->eigv,pod->iwork,
136: pod->yhay,pod->low);
137: #if defined(PETSC_USE_COMPLEX)
138: PetscFree(pod->rwork);
139: #endif
140: /* need to wait for completion before destroying dots_iallreduce */
141: if (pod->ndots_iallreduce) {
142: MPI_Wait(&pod->req_iallreduce,MPI_STATUS_IGNORE);
143: }
144: PetscFree(pod->dots_iallreduce);
145: PetscFree(pod->swork);
146: VecDestroyVecs(pod->maxn,&pod->bsnap);
147: VecDestroyVecs(pod->maxn,&pod->xsnap);
148: PetscFree(pod);
149: return(0);
150: }
152: static PetscErrorCode KSPGuessUpdate_POD(KSPGuess,Vec,Vec);
154: static PetscErrorCode KSPGuessFormGuess_POD(KSPGuess guess,Vec b,Vec x)
155: {
156: KSPGuessPOD *pod = (KSPGuessPOD*)guess->data;
158: PetscScalar one = 1, zero = 0, *array;
159: PetscBLASInt bN,ione = 1,bNen,lierr;
160: PetscInt i;
163: PetscCitationsRegister(citation,&cited);
164: if (pod->ndots_iallreduce) { /* complete communication and project the linear system */
165: KSPGuessUpdate_POD(guess,NULL,NULL);
166: }
167: if (!pod->nen) return(0);
168: /* b_low = S * V^T * X^T * b */
169: VecGetArrayRead(b,(const PetscScalar**)&array);
170: VecPlaceArray(pod->bsnap[pod->curr],array);
171: VecRestoreArrayRead(b,(const PetscScalar**)&array);
172: VecMDot(pod->bsnap[pod->curr],pod->n,pod->xsnap,pod->swork);
173: VecResetArray(pod->bsnap[pod->curr]);
174: MPIU_Allreduce(pod->swork,pod->swork + pod->n,pod->n,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)guess));
175: PetscBLASIntCast(pod->n,&bN);
176: PetscBLASIntCast(pod->nen,&bNen);
177: PetscStackCallBLAS("BLASgemv",BLASgemv_("T",&bN,&bNen,&one,pod->eigv+pod->st*pod->n,&bN,pod->swork+pod->n,&ione,&zero,pod->swork,&ione));
178: if (pod->monitor) {
179: PetscPrintf(PetscObjectComm((PetscObject)guess)," KSPGuessPOD alphas = ");
180: for (i=0; i<pod->nen; i++) {
181: #if defined(PETSC_USE_COMPLEX)
182: PetscPrintf(PetscObjectComm((PetscObject)guess),"%g + %g i",(double)PetscRealPart(pod->swork[i]),(double)PetscImaginaryPart(pod->swork[i]));
183: #else
184: PetscPrintf(PetscObjectComm((PetscObject)guess),"%g ",(double)pod->swork[i]);
185: #endif
186: }
187: PetscPrintf(PetscObjectComm((PetscObject)guess),"\n");
188: }
189: /* A_low x_low = b_low */
190: if (!pod->Aspd) { /* A is spd -> LOW = Identity */
191: KSP pksp = guess->ksp;
192: PetscBool tsolve,symm;
194: if (pod->monitor) {
195: PetscMPIInt rank;
196: Mat L;
198: MPI_Comm_rank(PetscObjectComm((PetscObject)guess),&rank);
199: MatCreateSeqDense(PETSC_COMM_SELF,pod->nen,pod->nen,pod->low,&L);
200: if (!rank) {
201: MatView(L,NULL);
202: }
203: MatDestroy(&L);
204: }
205: MatGetOption(guess->A,MAT_SYMMETRIC,&symm);
206: tsolve = symm ? PETSC_FALSE : pksp->transpose_solve;
207: PetscStackCallBLAS("LAPACKgetrf",LAPACKgetrf_(&bNen,&bNen,pod->low,&bNen,pod->iwork,&lierr));
208: if (lierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in GETRF Lapack routine %d",(int)lierr);
209: PetscStackCallBLAS("LAPACKgetrs",LAPACKgetrs_(tsolve ? "T" : "N",&bNen,&ione,pod->low,&bNen,pod->iwork,pod->swork,&bNen,&lierr));
210: if (lierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in GETRS Lapack routine %d",(int)lierr);
211: }
212: /* x = X * V * S * x_low */
213: PetscStackCallBLAS("BLASgemv",BLASgemv_("N",&bN,&bNen,&one,pod->eigv+pod->st*pod->n,&bN,pod->swork,&ione,&zero,pod->swork+pod->n,&ione));
214: if (pod->monitor) {
215: PetscPrintf(PetscObjectComm((PetscObject)guess)," KSPGuessPOD sol = ");
216: for (i=0; i<pod->nen; i++) {
217: #if defined(PETSC_USE_COMPLEX)
218: PetscPrintf(PetscObjectComm((PetscObject)guess),"%g + %g i",(double)PetscRealPart(pod->swork[i+pod->n]),(double)PetscImaginaryPart(pod->swork[i+pod->n]));
219: #else
220: PetscPrintf(PetscObjectComm((PetscObject)guess),"%g ",(double)pod->swork[i+pod->n]);
221: #endif
222: }
223: PetscPrintf(PetscObjectComm((PetscObject)guess),"\n");
224: }
225: VecGetArray(x,&array);
226: VecPlaceArray(pod->bsnap[pod->curr],array);
227: VecRestoreArray(x,&array);
228: VecSet(pod->bsnap[pod->curr],0);
229: VecMAXPY(pod->bsnap[pod->curr],pod->n,pod->swork+pod->n,pod->xsnap);
230: VecResetArray(pod->bsnap[pod->curr]);
231: PetscObjectStateIncrease((PetscObject)x);
232: return(0);
233: }
235: static PetscErrorCode KSPGuessUpdate_POD(KSPGuess guess, Vec b, Vec x)
236: {
237: KSPGuessPOD *pod = (KSPGuessPOD*)guess->data;
238: PetscScalar one = 1, zero = 0,*array;
239: PetscReal toten, parten, reps = 0; /* dlamch? */
240: PetscBLASInt bN,lierr,idummy;
241: PetscInt i;
245: if (pod->ndots_iallreduce) goto complete_request;
246: pod->n = pod->n < pod->maxn ? pod->n+1 : pod->maxn;
247: VecCopy(x,pod->xsnap[pod->curr]);
248: VecGetArray(pod->bsnap[pod->curr],&array);
249: VecPlaceArray(b,array);
250: VecRestoreArray(pod->bsnap[pod->curr],&array);
251: KSP_MatMult(guess->ksp,guess->A,x,b);
252: VecResetArray(b);
253: PetscObjectStateIncrease((PetscObject)pod->bsnap[pod->curr]);
254: if (pod->Aspd) {
255: VecMDot(pod->xsnap[pod->curr],pod->n,pod->bsnap,pod->swork);
256: #if !defined(PETSC_HAVE_MPI_IALLREDUCE)
257: MPIU_Allreduce(pod->swork,pod->swork + 3*pod->n,pod->n,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)guess));
258: #else
259: MPI_Iallreduce(pod->swork,pod->dots_iallreduce,pod->n,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)guess),&pod->req_iallreduce);
260: pod->ndots_iallreduce = 1;
261: #endif
262: } else {
263: PetscInt off;
264: PetscBool herm;
266: #if defined(PETSC_USE_COMPLEX)
267: MatGetOption(guess->A,MAT_HERMITIAN,&herm);
268: #else
269: MatGetOption(guess->A,MAT_SYMMETRIC,&herm);
270: #endif
271: off = (guess->ksp->transpose_solve && !herm) ? 2*pod->n : pod->n;
273: /* TODO: we may want to use a user-defined dot for the correlation matrix */
274: VecMDot(pod->xsnap[pod->curr],pod->n,pod->xsnap,pod->swork);
275: VecMDot(pod->bsnap[pod->curr],pod->n,pod->xsnap,pod->swork + off);
276: if (!herm) {
277: off = (off == pod->n) ? 2*pod->n : pod->n;
278: VecMDot(pod->xsnap[pod->curr],pod->n,pod->bsnap,pod->swork + off);
279: #if !defined(PETSC_HAVE_MPI_IALLREDUCE)
280: MPIU_Allreduce(pod->swork,pod->swork + 3*pod->n,3*pod->n,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)guess));
281: #else
282: MPI_Iallreduce(pod->swork,pod->dots_iallreduce,3*pod->n,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)guess),&pod->req_iallreduce);
283: pod->ndots_iallreduce = 3;
284: #endif
285: } else {
286: #if !defined(PETSC_HAVE_MPI_IALLREDUCE)
287: MPIU_Allreduce(pod->swork,pod->swork + 3*pod->n,2*pod->n,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)guess));
288: for (i=0;i<pod->n;i++) pod->swork[5*pod->n + i] = pod->swork[4*pod->n + i];
289: #else
290: MPI_Iallreduce(pod->swork,pod->dots_iallreduce,2*pod->n,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)guess),&pod->req_iallreduce);
291: pod->ndots_iallreduce = 2;
292: #endif
293: }
294: }
295: if (pod->ndots_iallreduce) return(0);
297: complete_request:
298: if (pod->ndots_iallreduce) {
299: MPI_Wait(&pod->req_iallreduce,MPI_STATUS_IGNORE);
300: switch (pod->ndots_iallreduce) {
301: case 3:
302: for (i=0;i<pod->n;i++) pod->swork[3*pod->n + i] = pod->dots_iallreduce[ i];
303: for (i=0;i<pod->n;i++) pod->swork[4*pod->n + i] = pod->dots_iallreduce[ pod->n+i];
304: for (i=0;i<pod->n;i++) pod->swork[5*pod->n + i] = pod->dots_iallreduce[2*pod->n+i];
305: break;
306: case 2:
307: for (i=0;i<pod->n;i++) pod->swork[3*pod->n + i] = pod->dots_iallreduce[ i];
308: for (i=0;i<pod->n;i++) pod->swork[4*pod->n + i] = pod->dots_iallreduce[pod->n+i];
309: for (i=0;i<pod->n;i++) pod->swork[5*pod->n + i] = pod->dots_iallreduce[pod->n+i];
310: break;
311: case 1:
312: for (i=0;i<pod->n;i++) pod->swork[3*pod->n + i] = pod->dots_iallreduce[i];
313: break;
314: default:
315: SETERRQ1(PetscObjectComm((PetscObject)guess),PETSC_ERR_PLIB,"Invalid number of outstanding dots operations: %D",pod->ndots_iallreduce);
316: break;
317: }
318: }
319: pod->ndots_iallreduce = 0;
321: /* correlation matrix and Y^H A Y (Galerkin) */
322: for (i=0;i<pod->n;i++) {
323: pod->corr[pod->curr*pod->maxn+i] = pod->swork[3*pod->n + i];
324: pod->corr[i*pod->maxn+pod->curr] = PetscConj(pod->swork[3*pod->n + i]);
325: if (!pod->Aspd) {
326: pod->yhay[pod->curr*pod->maxn+i] = pod->swork[4*pod->n + i];
327: pod->yhay[i*pod->maxn+pod->curr] = PetscConj(pod->swork[5*pod->n + i]);
328: }
329: }
330: /* syevx change the input matrix */
331: for (i=0;i<pod->n;i++) {
332: PetscInt j;
333: for (j=i;j<pod->n;j++) pod->swork[i*pod->n+j] = pod->corr[i*pod->maxn+j];
334: }
335: PetscBLASIntCast(pod->n,&bN);
336: #if !defined(PETSC_USE_COMPLEX)
337: PetscStackCallBLAS("LAPACKsyevx",LAPACKsyevx_("V","A","L",&bN,pod->swork,&bN,
338: &reps,&reps,&idummy,&idummy,
339: &reps,&idummy,pod->eigs,pod->eigv,&bN,
340: pod->swork+bN*bN,&pod->lwork,pod->iwork,pod->iwork+5*bN,&lierr));
341: #else
342: PetscStackCallBLAS("LAPACKsyevx",LAPACKsyevx_("V","A","L",&bN,pod->swork,&bN,
343: &reps,&reps,&idummy,&idummy,
344: &reps,&idummy,pod->eigs,pod->eigv,&bN,
345: pod->swork+bN*bN,&pod->lwork,pod->rwork,pod->iwork,pod->iwork+5*bN,&lierr));
346: #endif
347: if (lierr<0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in SYEV Lapack routine: illegal argument %d",-(int)lierr);
348: else if (lierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in SYEV Lapack routine: %d eigenvectors failed to converge",(int)lierr);
350: /* dimension of lower dimensional system */
351: pod->st = -1;
352: for (i=0,toten=0;i<pod->n;i++) {
353: pod->eigs[i] = PetscMax(pod->eigs[i],0.0);
354: toten += pod->eigs[i];
355: if (!pod->eigs[i]) pod->st = i;
356: }
357: pod->nen = 0;
358: for (i=pod->n-1,parten=0;i>pod->st && toten > 0;i--) {
359: pod->nen++;
360: parten += pod->eigs[i];
361: if (parten + toten*pod->tol >= toten) break;
362: }
363: pod->st = pod->n - pod->nen;
365: /* Compute eigv = V * S */
366: for (i=pod->st;i<pod->n;i++) {
367: const PetscReal v = 1.0/PetscSqrtReal(pod->eigs[i]);
368: const PetscInt st = pod->n*i;
369: PetscInt j;
371: for (j=0;j<pod->n;j++) pod->eigv[st+j] *= v;
372: }
374: /* compute S * V^T * X^T * A * X * V * S if needed */
375: if (pod->nen && !pod->Aspd) {
376: PetscBLASInt bNen,bMaxN;
377: PetscInt st = pod->st*pod->n;
378: PetscBLASIntCast(pod->nen,&bNen);
379: PetscBLASIntCast(pod->maxn,&bMaxN);
380: PetscStackCallBLAS("BLASgemm",BLASgemm_("T","N",&bNen,&bN,&bN,&one,pod->eigv+st,&bN,pod->yhay,&bMaxN,&zero,pod->swork,&bNen));
381: PetscStackCallBLAS("BLASgemm",BLASgemm_("N","N",&bNen,&bNen,&bN,&one,pod->swork,&bNen,pod->eigv+st,&bN,&zero,pod->low,&bNen));
382: }
384: if (pod->monitor) {
385: PetscPrintf(PetscObjectComm((PetscObject)guess)," KSPGuessPOD: basis %D, energy fractions = ",pod->nen);
386: for (i=pod->n-1;i>=0;i--) {
387: PetscPrintf(PetscObjectComm((PetscObject)guess),"%1.6e (%d) ",pod->eigs[i]/toten,i >= pod->st ? 1 : 0);
388: }
389: PetscPrintf(PetscObjectComm((PetscObject)guess),"\n");
390: #if defined(PETSC_USE_DEBUG)
391: for (i=0;i<pod->n;i++) {
392: Vec v;
393: PetscInt j;
394: PetscBLASInt bNen,ione = 1;
396: VecDuplicate(pod->xsnap[i],&v);
397: VecCopy(pod->xsnap[i],v);
398: PetscBLASIntCast(pod->nen,&bNen);
399: PetscStackCallBLAS("BLASgemv",BLASgemv_("T",&bN,&bNen,&one,pod->eigv+pod->st*pod->n,&bN,pod->corr+pod->maxn*i,&ione,&zero,pod->swork,&ione));
400: PetscStackCallBLAS("BLASgemv",BLASgemv_("N",&bN,&bNen,&one,pod->eigv+pod->st*pod->n,&bN,pod->swork,&ione,&zero,pod->swork+pod->n,&ione));
401: for (j=0;j<pod->n;j++) pod->swork[j] = -pod->swork[pod->n+j];
402: VecMAXPY(v,pod->n,pod->swork,pod->xsnap);
403: VecDot(v,v,pod->swork);
404: MPIU_Allreduce(pod->swork,pod->swork + 1,1,MPIU_SCALAR,MPIU_SUM,PetscObjectComm((PetscObject)guess));
405: PetscPrintf(PetscObjectComm((PetscObject)guess)," Error projection %D: %g (expected lower than %g)\n",i,(double)PetscRealPart(pod->swork[1]),(double)(toten-parten));
406: VecDestroy(&v);
407: }
408: #endif
409: }
410: /* new tip */
411: pod->curr = (pod->curr+1)%pod->maxn;
412: return(0);
413: }
415: static PetscErrorCode KSPGuessSetFromOptions_POD(KSPGuess guess)
416: {
417: KSPGuessPOD *pod = (KSPGuessPOD *)guess->data;
421: PetscOptionsBegin(PetscObjectComm((PetscObject)guess),((PetscObject)guess)->prefix,"POD initial guess options","KSPGuess");
422: PetscOptionsInt("-ksp_guess_pod_size","Number of snapshots",NULL,pod->maxn,&pod->maxn,NULL);
423: PetscOptionsBool("-ksp_guess_pod_monitor","Monitor initial guess generator",NULL,pod->monitor,&pod->monitor,NULL);
424: PetscOptionsReal("-ksp_guess_pod_tol","Tolerance to retain eigenvectors",NULL,pod->tol,&pod->tol,NULL);
425: PetscOptionsBool("-ksp_guess_pod_Ainner","Use the operator as inner product (must be SPD)",NULL,pod->Aspd,&pod->Aspd,NULL);
426: PetscOptionsEnd();
427: return(0);
428: }
430: static PetscErrorCode KSPGuessView_POD(KSPGuess guess,PetscViewer viewer)
431: {
432: KSPGuessPOD *pod = (KSPGuessPOD*)guess->data;
433: PetscBool isascii;
437: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&isascii);
438: if (isascii) {
439: PetscViewerASCIIPrintf(viewer,"Max size %D, tolerance %g, Ainner %d\n",pod->maxn,pod->tol,pod->Aspd);
440: }
441: return(0);
442: }
444: /*
445: KSPGUESSPOD - Implements a proper orthogonal decomposition based Galerkin scheme for repeated linear system solves.
447: The initial guess is obtained by solving a small and dense linear system, obtained by Galerkin projection on a lower dimensional space generated by the previous solutions.
448: The number of solutions to be retained and the energy tolerance to construct the lower dimensional basis can be specified at command line by -ksp_guess_pod_tol <real> and -ksp_guess_pod_size <int>.
450: References:
451: . 1. - http://www.math.uni-konstanz.de/numerik/personen/volkwein/teaching/POD-Book.pdf
453: Level: intermediate
455: .seealso: KSPGuess, KSPGuessType, KSPGuessCreate(), KSPSetGuess(), KSPGetGuess()
456: @*/
457: PetscErrorCode KSPGuessCreate_POD(KSPGuess guess)
458: {
459: KSPGuessPOD *pod;
463: PetscNewLog(guess,&pod);
464: pod->maxn = 10;
465: pod->tol = PETSC_MACHINE_EPSILON;
466: guess->data = pod;
468: guess->ops->setfromoptions = KSPGuessSetFromOptions_POD;
469: guess->ops->destroy = KSPGuessDestroy_POD;
470: guess->ops->setup = KSPGuessSetUp_POD;
471: guess->ops->view = KSPGuessView_POD;
472: guess->ops->reset = KSPGuessReset_POD;
473: guess->ops->update = KSPGuessUpdate_POD;
474: guess->ops->formguess = KSPGuessFormGuess_POD;
475: return(0);
476: }