Actual source code: gmres.c
1: #define PETSCKSP_DLL
3: /*
4: This file implements GMRES (a Generalized Minimal Residual) method.
5: Reference: Saad and Schultz, 1986.
8: Some comments on left vs. right preconditioning, and restarts.
9: Left and right preconditioning.
10: If right preconditioning is chosen, then the problem being solved
11: by gmres is actually
12: My = AB^-1 y = f
13: so the initial residual is
14: r = f - Mx
15: Note that B^-1 y = x or y = B x, and if x is non-zero, the initial
16: residual is
17: r = f - A x
18: The final solution is then
19: x = B^-1 y
21: If left preconditioning is chosen, then the problem being solved is
22: My = B^-1 A x = B^-1 f,
23: and the initial residual is
24: r = B^-1(f - Ax)
26: Restarts: Restarts are basically solves with x0 not equal to zero.
27: Note that we can eliminate an extra application of B^-1 between
28: restarts as long as we don't require that the solution at the end
29: of an unsuccessful gmres iteration always be the solution x.
30: */
32: #include src/ksp/ksp/impls/gmres/gmresp.h
33: #define GMRES_DELTA_DIRECTIONS 10
34: #define GMRES_DEFAULT_MAXK 30
35: static PetscErrorCode GMRESGetNewVectors(KSP,PetscInt);
36: static PetscErrorCode GMRESUpdateHessenberg(KSP,PetscInt,PetscTruth,PetscReal*);
37: static PetscErrorCode BuildGmresSoln(PetscScalar*,Vec,Vec,KSP,PetscInt);
41: PetscErrorCode KSPSetUp_GMRES(KSP ksp)
42: {
43: PetscInt size,hh,hes,rs,cc;
45: PetscInt max_k,k;
46: KSP_GMRES *gmres = (KSP_GMRES *)ksp->data;
49: if (ksp->pc_side == PC_SYMMETRIC) {
50: SETERRQ(PETSC_ERR_SUP,"no symmetric preconditioning for KSPGMRES");
51: }
53: max_k = gmres->max_k; /* restart size */
54: hh = (max_k + 2) * (max_k + 1);
55: hes = (max_k + 1) * (max_k + 1);
56: rs = (max_k + 2);
57: cc = (max_k + 1);
58: size = (hh + hes + rs + 2*cc) * sizeof(PetscScalar);
60: PetscMalloc(size,&gmres->hh_origin);
61: PetscMemzero(gmres->hh_origin,size);
62: PetscLogObjectMemory(ksp,size);
63: gmres->hes_origin = gmres->hh_origin + hh;
64: gmres->rs_origin = gmres->hes_origin + hes;
65: gmres->cc_origin = gmres->rs_origin + rs;
66: gmres->ss_origin = gmres->cc_origin + cc;
68: if (ksp->calc_sings) {
69: /* Allocate workspace to hold Hessenberg matrix needed by lapack */
70: size = (max_k + 3)*(max_k + 9)*sizeof(PetscScalar);
71: PetscMalloc(size,&gmres->Rsvd);
72: PetscMalloc(5*(max_k+2)*sizeof(PetscReal),&gmres->Dsvd);
73: PetscLogObjectMemory(ksp,size+5*(max_k+2)*sizeof(PetscReal));
74: }
76: /* Allocate array to hold pointers to user vectors. Note that we need
77: 4 + max_k + 1 (since we need it+1 vectors, and it <= max_k) */
78: PetscMalloc((VEC_OFFSET+2+max_k)*sizeof(void*),&gmres->vecs);
79: gmres->vecs_allocated = VEC_OFFSET + 2 + max_k;
80: PetscMalloc((VEC_OFFSET+2+max_k)*sizeof(void*),&gmres->user_work);
81: PetscMalloc((VEC_OFFSET+2+max_k)*sizeof(PetscInt),&gmres->mwork_alloc);
82: PetscLogObjectMemory(ksp,(VEC_OFFSET+2+max_k)*(2*sizeof(void*)+sizeof(PetscInt)));
84: if (gmres->q_preallocate) {
85: gmres->vv_allocated = VEC_OFFSET + 2 + max_k;
86: KSPGetVecs(ksp,gmres->vv_allocated,&gmres->user_work[0],0,PETSC_NULL);
87: PetscLogObjectParents(ksp,gmres->vv_allocated,gmres->user_work[0]);
88: gmres->mwork_alloc[0] = gmres->vv_allocated;
89: gmres->nwork_alloc = 1;
90: for (k=0; k<gmres->vv_allocated; k++) {
91: gmres->vecs[k] = gmres->user_work[0][k];
92: }
93: } else {
94: gmres->vv_allocated = 5;
95: KSPGetVecs(ksp,5,&gmres->user_work[0],0,PETSC_NULL);
96: PetscLogObjectParents(ksp,5,gmres->user_work[0]);
97: gmres->mwork_alloc[0] = 5;
98: gmres->nwork_alloc = 1;
99: for (k=0; k<gmres->vv_allocated; k++) {
100: gmres->vecs[k] = gmres->user_work[0][k];
101: }
102: }
103: return(0);
104: }
106: /*
107: Run gmres, possibly with restart. Return residual history if requested.
108: input parameters:
110: . gmres - structure containing parameters and work areas
112: output parameters:
113: . nres - residuals (from preconditioned system) at each step.
114: If restarting, consider passing nres+it. If null,
115: ignored
116: . itcount - number of iterations used. nres[0] to nres[itcount]
117: are defined. If null, ignored.
118:
119: Notes:
120: On entry, the value in vector VEC_VV(0) should be the initial residual
121: (this allows shortcuts where the initial preconditioned residual is 0).
122: */
125: PetscErrorCode GMREScycle(PetscInt *itcount,KSP ksp)
126: {
127: KSP_GMRES *gmres = (KSP_GMRES *)(ksp->data);
128: PetscReal res_norm,res,hapbnd,tt;
130: PetscInt it = 0, max_k = gmres->max_k;
131: PetscTruth hapend = PETSC_FALSE;
134: VecNormalize(VEC_VV(0),&res_norm);
135: res = res_norm;
136: *GRS(0) = res_norm;
138: /* check for the convergence */
139: PetscObjectTakeAccess(ksp);
140: ksp->rnorm = res;
141: PetscObjectGrantAccess(ksp);
142: gmres->it = (it - 1);
143: KSPLogResidualHistory(ksp,res);
144: if (!res) {
145: if (itcount) *itcount = 0;
146: ksp->reason = KSP_CONVERGED_ATOL;
147: PetscInfo(ksp,"Converged due to zero residual norm on entry\n");
148: return(0);
149: }
151: (*ksp->converged)(ksp,ksp->its,res,&ksp->reason,ksp->cnvP);
152: while (!ksp->reason && it < max_k && ksp->its < ksp->max_it) {
153: KSPLogResidualHistory(ksp,res);
154: gmres->it = (it - 1);
155: KSPMonitor(ksp,ksp->its,res);
156: if (gmres->vv_allocated <= it + VEC_OFFSET + 1) {
157: GMRESGetNewVectors(ksp,it+1);
158: }
159: KSP_PCApplyBAorAB(ksp,VEC_VV(it),VEC_VV(1+it),VEC_TEMP_MATOP);
161: /* update hessenberg matrix and do Gram-Schmidt */
162: (*gmres->orthog)(ksp,it);
164: /* vv(i+1) . vv(i+1) */
165: VecNormalize(VEC_VV(it+1),&tt);
166: /* save the magnitude */
167: *HH(it+1,it) = tt;
168: *HES(it+1,it) = tt;
170: /* check for the happy breakdown */
171: hapbnd = PetscAbsScalar(tt / *GRS(it));
172: if (hapbnd > gmres->haptol) hapbnd = gmres->haptol;
173: if (tt < hapbnd) {
174: PetscInfo2(ksp,"Detected happy breakdown, current hapbnd = %G tt = %G\n",hapbnd,tt);
175: hapend = PETSC_TRUE;
176: }
177: GMRESUpdateHessenberg(ksp,it,hapend,&res);
178: if (ksp->reason) break;
180: it++;
181: gmres->it = (it-1); /* For converged */
182: PetscObjectTakeAccess(ksp);
183: ksp->its++;
184: ksp->rnorm = res;
185: PetscObjectGrantAccess(ksp);
187: (*ksp->converged)(ksp,ksp->its,res,&ksp->reason,ksp->cnvP);
189: /* Catch error in happy breakdown and signal convergence and break from loop */
190: if (hapend) {
191: if (!ksp->reason) {
192: SETERRQ1(0,"You reached the happy break down, but convergence was not indicated. Residual norm = %G",res);
193: }
194: break;
195: }
196: }
198: /* Monitor if we know that we will not return for a restart */
199: if (ksp->reason || ksp->its >= ksp->max_it) {
200: KSPLogResidualHistory(ksp,res);
201: KSPMonitor(ksp,ksp->its,res);
202: }
204: if (itcount) *itcount = it;
207: /*
208: Down here we have to solve for the "best" coefficients of the Krylov
209: columns, add the solution values together, and possibly unwind the
210: preconditioning from the solution
211: */
212: /* Form the solution (or the solution so far) */
213: BuildGmresSoln(GRS(0),ksp->vec_sol,ksp->vec_sol,ksp,it-1);
215: return(0);
216: }
220: PetscErrorCode KSPSolve_GMRES(KSP ksp)
221: {
223: PetscInt its,itcount;
224: KSP_GMRES *gmres = (KSP_GMRES *)ksp->data;
225: PetscTruth guess_zero = ksp->guess_zero;
228: if (ksp->calc_sings && !gmres->Rsvd) {
229: SETERRQ(PETSC_ERR_ORDER,"Must call KSPSetComputeSingularValues() before KSPSetUp() is called");
230: }
232: PetscObjectTakeAccess(ksp);
233: ksp->its = 0;
234: PetscObjectGrantAccess(ksp);
236: itcount = 0;
237: ksp->reason = KSP_CONVERGED_ITERATING;
238: while (!ksp->reason) {
239: KSPInitialResidual(ksp,ksp->vec_sol,VEC_TEMP,VEC_TEMP_MATOP,VEC_VV(0),ksp->vec_rhs);
240: GMREScycle(&its,ksp);
241: itcount += its;
242: if (itcount >= ksp->max_it) {
243: ksp->reason = KSP_DIVERGED_ITS;
244: break;
245: }
246: ksp->guess_zero = PETSC_FALSE; /* every future call to KSPInitialResidual() will have nonzero guess */
247: }
248: ksp->guess_zero = guess_zero; /* restore if user provided nonzero initial guess */
249: return(0);
250: }
254: PetscErrorCode KSPDestroy_GMRES_Internal(KSP ksp)
255: {
256: KSP_GMRES *gmres = (KSP_GMRES*)ksp->data;
258: PetscInt i;
261: /* Free the Hessenberg matrix */
262: PetscFree(gmres->hh_origin);
264: /* Free the pointer to user variables */
265: PetscFree(gmres->vecs);
267: /* free work vectors */
268: for (i=0; i<gmres->nwork_alloc; i++) {
269: VecDestroyVecs(gmres->user_work[i],gmres->mwork_alloc[i]);
270: }
271: PetscFree(gmres->user_work);
272: PetscFree(gmres->mwork_alloc);
273: PetscFree(gmres->nrs);
274: if (gmres->sol_temp) {
275: VecDestroy(gmres->sol_temp);
276: }
277: PetscFree(gmres->Rsvd);
278: PetscFree(gmres->Dsvd);
279: PetscFree(gmres->orthogwork);
280: gmres->sol_temp = 0;
281: gmres->vv_allocated = 0;
282: gmres->vecs_allocated = 0;
283: gmres->sol_temp = 0;
284: return(0);
285: }
289: PetscErrorCode KSPDestroy_GMRES(KSP ksp)
290: {
291: KSP_GMRES *gmres = (KSP_GMRES*)ksp->data;
295: KSPDestroy_GMRES_Internal(ksp);
296: PetscFree(gmres);
297: return(0);
298: }
299: /*
300: BuildGmresSoln - create the solution from the starting vector and the
301: current iterates.
303: Input parameters:
304: nrs - work area of size it + 1.
305: vs - index of initial guess
306: vdest - index of result. Note that vs may == vdest (replace
307: guess with the solution).
309: This is an internal routine that knows about the GMRES internals.
310: */
313: static PetscErrorCode BuildGmresSoln(PetscScalar* nrs,Vec vs,Vec vdest,KSP ksp,PetscInt it)
314: {
315: PetscScalar tt;
317: PetscInt ii,k,j;
318: KSP_GMRES *gmres = (KSP_GMRES *)(ksp->data);
321: /* Solve for solution vector that minimizes the residual */
323: /* If it is < 0, no gmres steps have been performed */
324: if (it < 0) {
325: if (vdest != vs) {
326: VecCopy(vs,vdest);
327: }
328: return(0);
329: }
330: if (*HH(it,it) == 0.0) SETERRQ2(PETSC_ERR_CONV_FAILED,"HH(it,it) is identically zero; it = %D GRS(it) = %G",it,PetscAbsScalar(*GRS(it)));
331: if (*HH(it,it) != 0.0) {
332: nrs[it] = *GRS(it) / *HH(it,it);
333: } else {
334: nrs[it] = 0.0;
335: }
336: for (ii=1; ii<=it; ii++) {
337: k = it - ii;
338: tt = *GRS(k);
339: for (j=k+1; j<=it; j++) tt = tt - *HH(k,j) * nrs[j];
340: nrs[k] = tt / *HH(k,k);
341: }
343: /* Accumulate the correction to the solution of the preconditioned problem in TEMP */
344: VecSet(VEC_TEMP,0.0);
345: VecMAXPY(VEC_TEMP,it+1,nrs,&VEC_VV(0));
347: KSPUnwindPreconditioner(ksp,VEC_TEMP,VEC_TEMP_MATOP);
348: /* add solution to previous solution */
349: if (vdest != vs) {
350: VecCopy(vs,vdest);
351: }
352: VecAXPY(vdest,1.0,VEC_TEMP);
353: return(0);
354: }
355: /*
356: Do the scalar work for the orthogonalization. Return new residual.
357: */
360: static PetscErrorCode GMRESUpdateHessenberg(KSP ksp,PetscInt it,PetscTruth hapend,PetscReal *res)
361: {
362: PetscScalar *hh,*cc,*ss,tt;
363: PetscInt j;
364: KSP_GMRES *gmres = (KSP_GMRES *)(ksp->data);
367: hh = HH(0,it);
368: cc = CC(0);
369: ss = SS(0);
371: /* Apply all the previously computed plane rotations to the new column
372: of the Hessenberg matrix */
373: for (j=1; j<=it; j++) {
374: tt = *hh;
375: #if defined(PETSC_USE_COMPLEX)
376: *hh = PetscConj(*cc) * tt + *ss * *(hh+1);
377: #else
378: *hh = *cc * tt + *ss * *(hh+1);
379: #endif
380: hh++;
381: *hh = *cc++ * *hh - (*ss++ * tt);
382: }
384: /*
385: compute the new plane rotation, and apply it to:
386: 1) the right-hand-side of the Hessenberg system
387: 2) the new column of the Hessenberg matrix
388: thus obtaining the updated value of the residual
389: */
390: if (!hapend) {
391: #if defined(PETSC_USE_COMPLEX)
392: tt = PetscSqrtScalar(PetscConj(*hh) * *hh + PetscConj(*(hh+1)) * *(hh+1));
393: #else
394: tt = PetscSqrtScalar(*hh * *hh + *(hh+1) * *(hh+1));
395: #endif
396: if (tt == 0.0) {
397: ksp->reason = KSP_DIVERGED_NULL;
398: return(0);
399: }
400: *cc = *hh / tt;
401: *ss = *(hh+1) / tt;
402: *GRS(it+1) = - (*ss * *GRS(it));
403: #if defined(PETSC_USE_COMPLEX)
404: *GRS(it) = PetscConj(*cc) * *GRS(it);
405: *hh = PetscConj(*cc) * *hh + *ss * *(hh+1);
406: #else
407: *GRS(it) = *cc * *GRS(it);
408: *hh = *cc * *hh + *ss * *(hh+1);
409: #endif
410: *res = PetscAbsScalar(*GRS(it+1));
411: } else {
412: /* happy breakdown: HH(it+1, it) = 0, therfore we don't need to apply
413: another rotation matrix (so RH doesn't change). The new residual is
414: always the new sine term times the residual from last time (GRS(it)),
415: but now the new sine rotation would be zero...so the residual should
416: be zero...so we will multiply "zero" by the last residual. This might
417: not be exactly what we want to do here -could just return "zero". */
418:
419: *res = 0.0;
420: }
421: return(0);
422: }
423: /*
424: This routine allocates more work vectors, starting from VEC_VV(it).
425: */
428: static PetscErrorCode GMRESGetNewVectors(KSP ksp,PetscInt it)
429: {
430: KSP_GMRES *gmres = (KSP_GMRES *)ksp->data;
432: PetscInt nwork = gmres->nwork_alloc,k,nalloc;
435: nalloc = PetscMin(ksp->max_it,gmres->delta_allocate);
436: /* Adjust the number to allocate to make sure that we don't exceed the
437: number of available slots */
438: if (it + VEC_OFFSET + nalloc >= gmres->vecs_allocated){
439: nalloc = gmres->vecs_allocated - it - VEC_OFFSET;
440: }
441: if (!nalloc) return(0);
443: gmres->vv_allocated += nalloc;
444: KSPGetVecs(ksp,nalloc,&gmres->user_work[nwork],0,PETSC_NULL);
445: PetscLogObjectParents(ksp,nalloc,gmres->user_work[nwork]);
446: gmres->mwork_alloc[nwork] = nalloc;
447: for (k=0; k<nalloc; k++) {
448: gmres->vecs[it+VEC_OFFSET+k] = gmres->user_work[nwork][k];
449: }
450: gmres->nwork_alloc++;
451: return(0);
452: }
456: PetscErrorCode KSPBuildSolution_GMRES(KSP ksp,Vec ptr,Vec *result)
457: {
458: KSP_GMRES *gmres = (KSP_GMRES *)ksp->data;
462: if (!ptr) {
463: if (!gmres->sol_temp) {
464: VecDuplicate(ksp->vec_sol,&gmres->sol_temp);
465: PetscLogObjectParent(ksp,gmres->sol_temp);
466: }
467: ptr = gmres->sol_temp;
468: }
469: if (!gmres->nrs) {
470: /* allocate the work area */
471: PetscMalloc(gmres->max_k*sizeof(PetscScalar),&gmres->nrs);
472: PetscLogObjectMemory(ksp,gmres->max_k*sizeof(PetscScalar));
473: }
475: BuildGmresSoln(gmres->nrs,ksp->vec_sol,ptr,ksp,gmres->it);
476: *result = ptr;
477: return(0);
478: }
482: PetscErrorCode KSPView_GMRES(KSP ksp,PetscViewer viewer)
483: {
484: KSP_GMRES *gmres = (KSP_GMRES *)ksp->data;
485: const char *cstr;
487: PetscTruth iascii,isstring;
490: PetscTypeCompare((PetscObject)viewer,PETSC_VIEWER_ASCII,&iascii);
491: PetscTypeCompare((PetscObject)viewer,PETSC_VIEWER_STRING,&isstring);
492: if (gmres->orthog == KSPGMRESClassicalGramSchmidtOrthogonalization) {
493: switch (gmres->cgstype) {
494: case (KSP_GMRES_CGS_REFINE_NEVER):
495: cstr = "Classical (unmodified) Gram-Schmidt Orthogonalization with no iterative refinement";
496: break;
497: case (KSP_GMRES_CGS_REFINE_ALWAYS):
498: cstr = "Classical (unmodified) Gram-Schmidt Orthogonalization with one step of iterative refinement";
499: break;
500: case (KSP_GMRES_CGS_REFINE_IFNEEDED):
501: cstr = "Classical (unmodified) Gram-Schmidt Orthogonalization with one step of iterative refinement when needed";
502: break;
503: default:
504: SETERRQ(PETSC_ERR_ARG_OUTOFRANGE,"Unknown orthogonalization");
505: }
506: } else if (gmres->orthog == KSPGMRESModifiedGramSchmidtOrthogonalization) {
507: cstr = "Modified Gram-Schmidt Orthogonalization";
508: } else {
509: cstr = "unknown orthogonalization";
510: }
511: if (iascii) {
512: PetscViewerASCIIPrintf(viewer," GMRES: restart=%D, using %s\n",gmres->max_k,cstr);
513: PetscViewerASCIIPrintf(viewer," GMRES: happy breakdown tolerance %G\n",gmres->haptol);
514: } else if (isstring) {
515: PetscViewerStringSPrintf(viewer,"%s restart %D",cstr,gmres->max_k);
516: } else {
517: SETERRQ1(PETSC_ERR_SUP,"Viewer type %s not supported for KSP GMRES",((PetscObject)viewer)->type_name);
518: }
519: return(0);
520: }
524: /*@C
525: KSPGMRESKrylovMonitor - Calls VecView() for each direction in the
526: GMRES accumulated Krylov space.
528: Collective on KSP
530: Input Parameters:
531: + ksp - the KSP context
532: . its - iteration number
533: . fgnorm - 2-norm of residual (or gradient)
534: - a viewers object created with PetscViewersCreate()
536: Level: intermediate
538: .keywords: KSP, nonlinear, vector, monitor, view, Krylov space
540: .seealso: KSPSetMonitor(), KSPDefaultMonitor(), VecView(), PetscViewersCreate(), PetscViewersDestroy()
541: @*/
542: PetscErrorCode KSPGMRESKrylovMonitor(KSP ksp,PetscInt its,PetscReal fgnorm,void *dummy)
543: {
544: PetscViewers viewers = (PetscViewers)dummy;
545: KSP_GMRES *gmres = (KSP_GMRES*)ksp->data;
547: Vec x;
548: PetscViewer viewer;
551: PetscViewersGetViewer(viewers,gmres->it+1,&viewer);
552: PetscViewerSetType(viewer,PETSC_VIEWER_DRAW);
554: x = VEC_VV(gmres->it+1);
555: VecView(x,viewer);
557: return(0);
558: }
562: PetscErrorCode KSPSetFromOptions_GMRES(KSP ksp)
563: {
565: PetscInt restart;
566: PetscReal haptol;
567: KSP_GMRES *gmres = (KSP_GMRES*)ksp->data;
568: PetscTruth flg;
571: PetscOptionsHead("KSP GMRES Options");
572: PetscOptionsInt("-ksp_gmres_restart","Number of Krylov search directions","KSPGMRESSetRestart",gmres->max_k,&restart,&flg);
573: if (flg) { KSPGMRESSetRestart(ksp,restart); }
574: PetscOptionsReal("-ksp_gmres_haptol","Tolerance for exact convergence (happy ending)","KSPGMRESSetHapTol",gmres->haptol,&haptol,&flg);
575: if (flg) { KSPGMRESSetHapTol(ksp,haptol); }
576: PetscOptionsName("-ksp_gmres_preallocate","Preallocate Krylov vectors","KSPGMRESSetPreAllocateVectors",&flg);
577: if (flg) {KSPGMRESSetPreAllocateVectors(ksp);}
578: PetscOptionsTruthGroupBegin("-ksp_gmres_classicalgramschmidt","Classical (unmodified) Gram-Schmidt (fast)","KSPGMRESSetOrthogonalization",&flg);
579: if (flg) {KSPGMRESSetOrthogonalization(ksp,KSPGMRESClassicalGramSchmidtOrthogonalization);}
580: PetscOptionsTruthGroupEnd("-ksp_gmres_modifiedgramschmidt","Modified Gram-Schmidt (slow,more stable)","KSPGMRESSetOrthogonalization",&flg);
581: if (flg) {KSPGMRESSetOrthogonalization(ksp,KSPGMRESModifiedGramSchmidtOrthogonalization);}
582: PetscOptionsEnum("-ksp_gmres_cgs_refinement_type","Type of iterative refinement for classical (unmodified) Gram-Schmidt","KSPGMRESSetCGSRefinementType",
583: KSPGMRESCGSRefinementTypes,(PetscEnum)gmres->cgstype,(PetscEnum*)&gmres->cgstype,&flg);
584: PetscOptionsName("-ksp_gmres_krylov_monitor","Plot the Krylov directions","KSPSetMonitor",&flg);
585: if (flg) {
586: PetscViewers viewers;
587: PetscViewersCreate(ksp->comm,&viewers);
588: KSPSetMonitor(ksp,KSPGMRESKrylovMonitor,viewers,(PetscErrorCode (*)(void*))PetscViewersDestroy);
589: }
590: PetscOptionsTail();
591: return(0);
592: }
594: EXTERN PetscErrorCode KSPComputeExtremeSingularValues_GMRES(KSP,PetscReal *,PetscReal *);
595: EXTERN PetscErrorCode KSPComputeEigenvalues_GMRES(KSP,PetscInt,PetscReal *,PetscReal *,PetscInt *);
601: PetscErrorCode KSPGMRESSetHapTol_GMRES(KSP ksp,PetscReal tol)
602: {
603: KSP_GMRES *gmres = (KSP_GMRES *)ksp->data;
606: if (tol < 0.0) SETERRQ(PETSC_ERR_ARG_OUTOFRANGE,"Tolerance must be non-negative");
607: gmres->haptol = tol;
608: return(0);
609: }
615: PetscErrorCode KSPGMRESSetRestart_GMRES(KSP ksp,PetscInt max_k)
616: {
617: KSP_GMRES *gmres = (KSP_GMRES *)ksp->data;
621: if (max_k < 1) SETERRQ(PETSC_ERR_ARG_OUTOFRANGE,"Restart must be positive");
622: if (!ksp->setupcalled) {
623: gmres->max_k = max_k;
624: } else if (gmres->max_k != max_k) {
625: gmres->max_k = max_k;
626: ksp->setupcalled = 0;
627: /* free the data structures, then create them again */
628: KSPDestroy_GMRES_Internal(ksp);
629: }
630: return(0);
631: }
638: PetscErrorCode KSPGMRESSetOrthogonalization_GMRES(KSP ksp,FCN fcn)
639: {
642: ((KSP_GMRES *)ksp->data)->orthog = fcn;
643: return(0);
644: }
650: PetscErrorCode KSPGMRESSetPreAllocateVectors_GMRES(KSP ksp)
651: {
652: KSP_GMRES *gmres;
655: gmres = (KSP_GMRES *)ksp->data;
656: gmres->q_preallocate = 1;
657: return(0);
658: }
664: PetscErrorCode KSPGMRESSetCGSRefinementType_GMRES(KSP ksp,KSPGMRESCGSRefinementType type)
665: {
666: KSP_GMRES *gmres = (KSP_GMRES*)ksp->data;
669: gmres->cgstype = type;
670: return(0);
671: }
676: /*@
677: KSPGMRESSetCGSRefinementType - Sets the type of iterative refinement to use
678: in the classical Gram Schmidt orthogonalization.
679: of the preconditioned problem.
681: Collective on KSP
683: Input Parameters:
684: + ksp - the Krylov space context
685: - type - the type of refinement
687: Options Database:
688: . -ksp_gmres_cgs_refinement_type <never,ifneeded,always>
690: Level: intermediate
692: .keywords: KSP, GMRES, iterative refinement
694: .seealso: KSPGMRESSetOrthogonalization(), KSPGMRESCGSRefinementType, KSPGMRESClassicalGramSchmidtOrthogonalization()
695: @*/
696: PetscErrorCode KSPGMRESSetCGSRefinementType(KSP ksp,KSPGMRESCGSRefinementType type)
697: {
698: PetscErrorCode ierr,(*f)(KSP,KSPGMRESCGSRefinementType);
702: PetscObjectQueryFunction((PetscObject)ksp,"KSPGMRESSetCGSRefinementType_C",(void (**)(void))&f);
703: if (f) {
704: (*f)(ksp,type);
705: }
706: return(0);
707: }
711: /*@
712: KSPGMRESSetRestart - Sets number of iterations at which GMRES, FGMRES and LGMRES restarts.
714: Collective on KSP
716: Input Parameters:
717: + ksp - the Krylov space context
718: - restart - integer restart value
720: Options Database:
721: . -ksp_gmres_restart <positive integer>
723: Note: The default value is 30.
725: Level: intermediate
727: .keywords: KSP, GMRES, restart, iterations
729: .seealso: KSPSetTolerances(), KSPGMRESSetOrthogonalization(), KSPGMRESSetPreAllocateVectors()
730: @*/
731: PetscErrorCode KSPGMRESSetRestart(KSP ksp, PetscInt restart)
732: {
736: PetscTryMethod(ksp,KSPGMRESSetRestart_C,(KSP,PetscInt),(ksp,restart));
737: return(0);
738: }
742: /*@
743: KSPGMRESSetHapTol - Sets tolerance for determining happy breakdown in GMRES, FGMRES and LGMRES.
745: Collective on KSP
747: Input Parameters:
748: + ksp - the Krylov space context
749: - tol - the tolerance
751: Options Database:
752: . -ksp_gmres_haptol <positive real value>
754: Note: Happy breakdown is the rare case in GMRES where an 'exact' solution is obtained after
755: a certain number of iterations. If you attempt more iterations after this point unstable
756: things can happen hence very occasionally you may need to set this value to detect this condition
758: Level: intermediate
760: .keywords: KSP, GMRES, tolerance
762: .seealso: KSPSetTolerances()
763: @*/
764: PetscErrorCode KSPGMRESSetHapTol(KSP ksp,PetscReal tol)
765: {
769: PetscTryMethod((ksp),KSPGMRESSetHapTol_C,(KSP,PetscReal),((ksp),(tol)));
770: return(0);
771: }
773: /*MC
774: KSPGMRES - Implements the Generalized Minimal Residual method.
775: (Saad and Schultz, 1986) with restart
778: Options Database Keys:
779: + -ksp_gmres_restart <restart> - the number of Krylov directions to orthogonalize against
780: . -ksp_gmres_haptol <tol> - sets the tolerance for "happy ending" (exact convergence)
781: . -ksp_gmres_preallocate - preallocate all the Krylov search directions initially (otherwise groups of
782: vectors are allocated as needed)
783: . -ksp_gmres_classicalgramschmidt - use classical (unmodified) Gram-Schmidt to orthogonalize against the Krylov space (fast) (the default)
784: . -ksp_gmres_modifiedgramschmidt - use modified Gram-Schmidt in the orthogonalization (more stable, but slower)
785: . -ksp_gmres_cgs_refinement_type <never,ifneeded,always> - determine if iterative refinement is used to increase the
786: stability of the classical Gram-Schmidt orthogonalization.
787: - -ksp_gmres_krylov_monitor - plot the Krylov space generated
789: Level: beginner
792: .seealso: KSPCreate(), KSPSetType(), KSPType (for list of available types), KSP, KSPFGMRES, KSPLGMRES,
793: KSPGMRESSetRestart(), KSPGMRESSetHapTol(), KSPGMRESSetPreAllocateVectors(), KSPGMRESSetOrthogonalization()
794: KSPGMRESClassicalGramSchmidtOrthogonalization(), KSPGMRESModifiedGramSchmidtOrthogonalization(),
795: KSPGMRESCGSRefinementType, KSPGMRESSetCGSRefinementType(), KSPGMRESKrylovMonitor()
797: M*/
802: PetscErrorCode KSPCreate_GMRES(KSP ksp)
803: {
804: KSP_GMRES *gmres;
808: PetscNew(KSP_GMRES,&gmres);
809: PetscLogObjectMemory(ksp,sizeof(KSP_GMRES));
810: ksp->data = (void*)gmres;
811: ksp->ops->buildsolution = KSPBuildSolution_GMRES;
813: ksp->ops->setup = KSPSetUp_GMRES;
814: ksp->ops->solve = KSPSolve_GMRES;
815: ksp->ops->destroy = KSPDestroy_GMRES;
816: ksp->ops->view = KSPView_GMRES;
817: ksp->ops->setfromoptions = KSPSetFromOptions_GMRES;
818: ksp->ops->computeextremesingularvalues = KSPComputeExtremeSingularValues_GMRES;
819: ksp->ops->computeeigenvalues = KSPComputeEigenvalues_GMRES;
821: PetscObjectComposeFunctionDynamic((PetscObject)ksp,"KSPGMRESSetPreAllocateVectors_C",
822: "KSPGMRESSetPreAllocateVectors_GMRES",
823: KSPGMRESSetPreAllocateVectors_GMRES);
824: PetscObjectComposeFunctionDynamic((PetscObject)ksp,"KSPGMRESSetOrthogonalization_C",
825: "KSPGMRESSetOrthogonalization_GMRES",
826: KSPGMRESSetOrthogonalization_GMRES);
827: PetscObjectComposeFunctionDynamic((PetscObject)ksp,"KSPGMRESSetRestart_C",
828: "KSPGMRESSetRestart_GMRES",
829: KSPGMRESSetRestart_GMRES);
830: PetscObjectComposeFunctionDynamic((PetscObject)ksp,"KSPGMRESSetHapTol_C",
831: "KSPGMRESSetHapTol_GMRES",
832: KSPGMRESSetHapTol_GMRES);
833: PetscObjectComposeFunctionDynamic((PetscObject)ksp,"KSPGMRESSetCGSRefinementType_C",
834: "KSPGMRESSetCGSRefinementType_GMRES",
835: KSPGMRESSetCGSRefinementType_GMRES);
837: gmres->haptol = 1.0e-30;
838: gmres->q_preallocate = 0;
839: gmres->delta_allocate = GMRES_DELTA_DIRECTIONS;
840: gmres->orthog = KSPGMRESClassicalGramSchmidtOrthogonalization;
841: gmres->nrs = 0;
842: gmres->sol_temp = 0;
843: gmres->max_k = GMRES_DEFAULT_MAXK;
844: gmres->Rsvd = 0;
845: gmres->cgstype = KSP_GMRES_CGS_REFINE_NEVER;
846: gmres->orthogwork = 0;
847: return(0);
848: }