2: #include <../src/ksp/ksp/impls/gmres/lgmres/lgmresimpl.h> /*I petscksp.h I*/
4: #define LGMRES_DELTA_DIRECTIONS 10 5: #define LGMRES_DEFAULT_MAXK 30 6: #define LGMRES_DEFAULT_AUGDIM 2 /*default number of augmentation vectors */ 7: static PetscErrorCode KSPLGMRESGetNewVectors(KSP,PetscInt);
8: static PetscErrorCode KSPLGMRESUpdateHessenberg(KSP,PetscInt,PetscBool,PetscReal*);
9: static PetscErrorCode KSPLGMRESBuildSoln(PetscScalar*,Vec,Vec,KSP,PetscInt);
13: PetscErrorCode KSPLGMRESSetAugDim(KSP ksp, PetscInt dim) 14: {
18: PetscTryMethod((ksp),"KSPLGMRESSetAugDim_C",(KSP,PetscInt),(ksp,dim));
19: return(0);
20: }
24: PetscErrorCode KSPLGMRESSetConstant(KSP ksp) 25: {
29: PetscTryMethod((ksp),"KSPLGMRESSetConstant_C",(KSP),(ksp));
30: return(0);
31: }
33: /*
34: KSPSetUp_LGMRES - Sets up the workspace needed by lgmres.
36: This is called once, usually automatically by KSPSolve() or KSPSetUp(),
37: but can be called directly by KSPSetUp().
39: */
42: PetscErrorCode KSPSetUp_LGMRES(KSP ksp) 43: {
45: PetscInt max_k,k, aug_dim;
46: KSP_LGMRES *lgmres = (KSP_LGMRES*)ksp->data;
49: max_k = lgmres->max_k;
50: aug_dim = lgmres->aug_dim;
51: KSPSetUp_GMRES(ksp);
53: /* need array of pointers to augvecs*/
54: PetscMalloc1(2*aug_dim + AUG_OFFSET,&lgmres->augvecs);
56: lgmres->aug_vecs_allocated = 2 *aug_dim + AUG_OFFSET;
58: PetscMalloc1(2*aug_dim + AUG_OFFSET,&lgmres->augvecs_user_work);
59: PetscMalloc1(aug_dim,&lgmres->aug_order);
60: PetscLogObjectMemory((PetscObject)ksp,(aug_dim)*(4*sizeof(void*) + sizeof(PetscInt)) + AUG_OFFSET*2*sizeof(void*));
62: /* for now we will preallocate the augvecs - because aug_dim << restart
63: ... also keep in mind that we need to keep augvecs from cycle to cycle*/
64: lgmres->aug_vv_allocated = 2* aug_dim + AUG_OFFSET;
65: lgmres->augwork_alloc = 2* aug_dim + AUG_OFFSET;
67: KSPCreateVecs(ksp,lgmres->aug_vv_allocated,&lgmres->augvecs_user_work[0],0,NULL);
68: PetscMalloc1(max_k+1,&lgmres->hwork);
69: PetscLogObjectParents(ksp,lgmres->aug_vv_allocated,lgmres->augvecs_user_work[0]);
70: for (k=0; k<lgmres->aug_vv_allocated; k++) {
71: lgmres->augvecs[k] = lgmres->augvecs_user_work[0][k];
72: }
73: return(0);
74: }
77: /*
79: KSPLGMRESCycle - Run lgmres, possibly with restart. Return residual
80: history if requested.
82: input parameters:
83: . lgmres - structure containing parameters and work areas
85: output parameters:
86: . nres - residuals (from preconditioned system) at each step.
87: If restarting, consider passing nres+it. If null,
88: ignored
89: . itcount - number of iterations used. nres[0] to nres[itcount]
90: are defined. If null, ignored. If null, ignored.
91: . converged - 0 if not converged
94: Notes:
95: On entry, the value in vector VEC_VV(0) should be
96: the initial residual.
99: */
102: PetscErrorCode KSPLGMRESCycle(PetscInt *itcount,KSP ksp)103: {
104: KSP_LGMRES *lgmres = (KSP_LGMRES*)(ksp->data);
105: PetscReal res_norm, res;
106: PetscReal hapbnd, tt;
107: PetscScalar tmp;
108: PetscBool hapend = PETSC_FALSE; /* indicates happy breakdown ending */
110: PetscInt loc_it; /* local count of # of dir. in Krylov space */
111: PetscInt max_k = lgmres->max_k; /* max approx space size */
112: PetscInt max_it = ksp->max_it; /* max # of overall iterations for the method */
114: /* LGMRES_MOD - new variables*/
115: PetscInt aug_dim = lgmres->aug_dim;
116: PetscInt spot = 0;
117: PetscInt order = 0;
118: PetscInt it_arnoldi; /* number of arnoldi steps to take */
119: PetscInt it_total; /* total number of its to take (=approx space size)*/
120: PetscInt ii, jj;
121: PetscReal tmp_norm;
122: PetscScalar inv_tmp_norm;
123: PetscScalar *avec;
126: /* Number of pseudo iterations since last restart is the number
127: of prestart directions */
128: loc_it = 0;
130: /* LGMRES_MOD: determine number of arnoldi steps to take */
131: /* if approx_constant then we keep the space the same size even if
132: we don't have the full number of aug vectors yet*/
133: if (lgmres->approx_constant) it_arnoldi = max_k - lgmres->aug_ct;
134: else it_arnoldi = max_k - aug_dim;
136: it_total = it_arnoldi + lgmres->aug_ct;
138: /* initial residual is in VEC_VV(0) - compute its norm*/
139: VecNorm(VEC_VV(0),NORM_2,&res_norm);
140: KSPCheckNorm(ksp,res_norm);
141: res = res_norm;
143: /* first entry in right-hand-side of hessenberg system is just
144: the initial residual norm */
145: *GRS(0) = res_norm;
147: /* check for the convergence */
148: if (!res) {
149: if (itcount) *itcount = 0;
150: ksp->reason = KSP_CONVERGED_ATOL;
151: PetscInfo(ksp,"Converged due to zero residual norm on entry\n");
152: return(0);
153: }
155: /* scale VEC_VV (the initial residual) */
156: tmp = 1.0/res_norm; VecScale(VEC_VV(0),tmp);
158: ksp->rnorm = res;
161: /* note: (lgmres->it) is always set one less than (loc_it) It is used in
162: KSPBUILDSolution_LGMRES, where it is passed to KSPLGMRESBuildSoln.
163: Note that when KSPLGMRESBuildSoln is called from this function,
164: (loc_it -1) is passed, so the two are equivalent */
165: lgmres->it = (loc_it - 1);
168: /* MAIN ITERATION LOOP BEGINNING*/
171: /* keep iterating until we have converged OR generated the max number
172: of directions OR reached the max number of iterations for the method */
173: (*ksp->converged)(ksp,ksp->its,res,&ksp->reason,ksp->cnvP);
175: while (!ksp->reason && loc_it < it_total && ksp->its < max_it) { /* LGMRES_MOD: changed to it_total */
176: KSPLogResidualHistory(ksp,res);
177: lgmres->it = (loc_it - 1);
178: KSPMonitor(ksp,ksp->its,res);
180: /* see if more space is needed for work vectors */
181: if (lgmres->vv_allocated <= loc_it + VEC_OFFSET + 1) {
182: KSPLGMRESGetNewVectors(ksp,loc_it+1);
183: /* (loc_it+1) is passed in as number of the first vector that should
184: be allocated */
185: }
187: /*LGMRES_MOD: decide whether this is an arnoldi step or an aug step */
188: if (loc_it < it_arnoldi) { /* Arnoldi */
189: KSP_PCApplyBAorAB(ksp,VEC_VV(loc_it),VEC_VV(1+loc_it),VEC_TEMP_MATOP);
190: } else { /*aug step */
191: order = loc_it - it_arnoldi + 1; /* which aug step */
192: for (ii=0; ii<aug_dim; ii++) {
193: if (lgmres->aug_order[ii] == order) {
194: spot = ii;
195: break; /* must have this because there will be duplicates before aug_ct = aug_dim */
196: }
197: }
199: VecCopy(A_AUGVEC(spot), VEC_VV(1+loc_it));
200: /*note: an alternate implementation choice would be to only save the AUGVECS and
201: not A_AUGVEC and then apply the PC here to the augvec */
202: }
204: /* update hessenberg matrix and do Gram-Schmidt - new direction is in
205: VEC_VV(1+loc_it)*/
206: (*lgmres->orthog)(ksp,loc_it);
208: /* new entry in hessenburg is the 2-norm of our new direction */
209: VecNorm(VEC_VV(loc_it+1),NORM_2,&tt);
211: *HH(loc_it+1,loc_it) = tt;
212: *HES(loc_it+1,loc_it) = tt;
215: /* check for the happy breakdown */
216: hapbnd = PetscAbsScalar(tt / *GRS(loc_it)); /* GRS(loc_it) contains the res_norm from the last iteration */
217: if (hapbnd > lgmres->haptol) hapbnd = lgmres->haptol;
218: if (tt > hapbnd) {
219: tmp = 1.0/tt;
220: VecScale(VEC_VV(loc_it+1),tmp); /* scale new direction by its norm */
221: } else {
222: PetscInfo2(ksp,"Detected happy breakdown, current hapbnd = %g tt = %g\n",(double)hapbnd,(double)tt);
223: hapend = PETSC_TRUE;
224: }
226: /* Now apply rotations to new col of hessenberg (and right side of system),
227: calculate new rotation, and get new residual norm at the same time*/
228: KSPLGMRESUpdateHessenberg(ksp,loc_it,hapend,&res);
229: if (ksp->reason) break;
231: loc_it++;
232: lgmres->it = (loc_it-1); /* Add this here in case it has converged */
234: PetscObjectSAWsTakeAccess((PetscObject)ksp);
235: ksp->its++;
236: ksp->rnorm = res;
237: PetscObjectSAWsGrantAccess((PetscObject)ksp);
239: (*ksp->converged)(ksp,ksp->its,res,&ksp->reason,ksp->cnvP);
241: /* Catch error in happy breakdown and signal convergence and break from loop */
242: if (hapend) {
243: if (!ksp->reason) {
244: if (ksp->errorifnotconverged) SETERRQ1(PetscObjectComm((PetscObject)ksp),PETSC_ERR_NOT_CONVERGED,"You reached the happy break down, but convergence was not indicated. Residual norm = %g",(double)res);
245: else {
246: ksp->reason = KSP_DIVERGED_BREAKDOWN;
247: break;
248: }
249: }
250: }
251: }
252: /* END OF ITERATION LOOP */
253: KSPLogResidualHistory(ksp,res);
255: /* Monitor if we know that we will not return for a restart */
256: if (ksp->reason || ksp->its >= max_it) {
257: KSPMonitor(ksp, ksp->its, res);
258: }
260: if (itcount) *itcount = loc_it;
262: /*
263: Down here we have to solve for the "best" coefficients of the Krylov
264: columns, add the solution values together, and possibly unwind the
265: preconditioning from the solution
266: */
268: /* Form the solution (or the solution so far) */
269: /* Note: must pass in (loc_it-1) for iteration count so that KSPLGMRESBuildSoln
270: properly navigates */
272: KSPLGMRESBuildSoln(GRS(0),ksp->vec_sol,ksp->vec_sol,ksp,loc_it-1);
275: /* LGMRES_MOD collect aug vector and A*augvector for future restarts -
276: only if we will be restarting (i.e. this cycle performed it_total
277: iterations) */
278: if (!ksp->reason && ksp->its < max_it && aug_dim > 0) {
280: /*AUG_TEMP contains the new augmentation vector (assigned in KSPLGMRESBuildSoln) */
281: if (!lgmres->aug_ct) {
282: spot = 0;
283: lgmres->aug_ct++;
284: } else if (lgmres->aug_ct < aug_dim) {
285: spot = lgmres->aug_ct;
286: lgmres->aug_ct++;
287: } else { /* truncate */
288: for (ii=0; ii<aug_dim; ii++) {
289: if (lgmres->aug_order[ii] == aug_dim) spot = ii;
290: }
291: }
295: VecCopy(AUG_TEMP, AUGVEC(spot));
296: /*need to normalize */
297: VecNorm(AUGVEC(spot), NORM_2, &tmp_norm);
299: inv_tmp_norm = 1.0/tmp_norm;
301: VecScale(AUGVEC(spot),inv_tmp_norm);
303: /*set new aug vector to order 1 - move all others back one */
304: for (ii=0; ii < aug_dim; ii++) AUG_ORDER(ii)++;
305: AUG_ORDER(spot) = 1;
307: /*now add the A*aug vector to A_AUGVEC(spot) - this is independ. of preconditioning type*/
308: /* want V*H*y - y is in GRS, V is in VEC_VV and H is in HES */
311: /* first do H+*y */
312: avec = lgmres->hwork;
313: PetscMemzero(avec,(it_total+1)*sizeof(*avec));
314: for (ii=0; ii < it_total + 1; ii++) {
315: for (jj=0; jj <= ii+1 && jj < it_total+1; jj++) {
316: avec[jj] += *HES(jj ,ii) * *GRS(ii);
317: }
318: }
320: /*now multiply result by V+ */
321: VecSet(VEC_TEMP,0.0);
322: VecMAXPY(VEC_TEMP, it_total+1, avec, &VEC_VV(0)); /*answer is in VEC_TEMP*/
324: /*copy answer to aug location and scale*/
325: VecCopy(VEC_TEMP, A_AUGVEC(spot));
326: VecScale(A_AUGVEC(spot),inv_tmp_norm);
327: }
328: return(0);
329: }
331: /*
332: KSPSolve_LGMRES - This routine applies the LGMRES method.
335: Input Parameter:
336: . ksp - the Krylov space object that was set to use lgmres
338: Output Parameter:
339: . outits - number of iterations used
341: */
345: PetscErrorCode KSPSolve_LGMRES(KSP ksp)346: {
348: PetscInt cycle_its; /* iterations done in a call to KSPLGMRESCycle */
349: PetscInt itcount; /* running total of iterations, incl. those in restarts */
350: KSP_LGMRES *lgmres = (KSP_LGMRES*)ksp->data;
351: PetscBool guess_zero = ksp->guess_zero;
352: PetscInt ii; /*LGMRES_MOD variable */
355: if (ksp->calc_sings && !lgmres->Rsvd) SETERRQ(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ORDER,"Must call KSPSetComputeSingularValues() before KSPSetUp() is called");
357: PetscObjectSAWsTakeAccess((PetscObject)ksp);
359: ksp->its = 0;
360: lgmres->aug_ct = 0;
361: lgmres->matvecs = 0;
363: PetscObjectSAWsGrantAccess((PetscObject)ksp);
365: /* initialize */
366: itcount = 0;
367: ksp->reason = KSP_CONVERGED_ITERATING;
368: /*LGMRES_MOD*/
369: for (ii=0; ii<lgmres->aug_dim; ii++) lgmres->aug_order[ii] = 0;
371: while (!ksp->reason) {
372: /* calc residual - puts in VEC_VV(0) */
373: KSPInitialResidual(ksp,ksp->vec_sol,VEC_TEMP,VEC_TEMP_MATOP,VEC_VV(0),ksp->vec_rhs);
374: KSPLGMRESCycle(&cycle_its,ksp);
375: itcount += cycle_its;
376: if (itcount >= ksp->max_it) {
377: if (!ksp->reason) ksp->reason = KSP_DIVERGED_ITS;
378: break;
379: }
380: ksp->guess_zero = PETSC_FALSE; /* every future call to KSPInitialResidual() will have nonzero guess */
381: }
382: ksp->guess_zero = guess_zero; /* restore if user provided nonzero initial guess */
383: return(0);
384: }
386: /*
388: KSPDestroy_LGMRES - Frees all memory space used by the Krylov method.
390: */
393: PetscErrorCode KSPDestroy_LGMRES(KSP ksp)394: {
395: KSP_LGMRES *lgmres = (KSP_LGMRES*)ksp->data;
399: PetscFree(lgmres->augvecs);
400: if (lgmres->augwork_alloc) {
401: VecDestroyVecs(lgmres->augwork_alloc,&lgmres->augvecs_user_work[0]);
402: }
403: PetscFree(lgmres->augvecs_user_work);
404: PetscFree(lgmres->aug_order);
405: PetscFree(lgmres->hwork);
406: KSPDestroy_GMRES(ksp);
407: return(0);
408: }
410: /*
411: KSPLGMRESBuildSoln - create the solution from the starting vector and the
412: current iterates.
414: Input parameters:
415: nrs - work area of size it + 1.
416: vguess - index of initial guess
417: vdest - index of result. Note that vguess may == vdest (replace
418: guess with the solution).
419: it - HH upper triangular part is a block of size (it+1) x (it+1)
421: This is an internal routine that knows about the LGMRES internals.
422: */
425: static PetscErrorCode KSPLGMRESBuildSoln(PetscScalar *nrs,Vec vguess,Vec vdest,KSP ksp,PetscInt it)426: {
427: PetscScalar tt;
429: PetscInt ii,k,j;
430: KSP_LGMRES *lgmres = (KSP_LGMRES*)(ksp->data);
431: /*LGMRES_MOD */
432: PetscInt it_arnoldi, it_aug;
433: PetscInt jj, spot = 0;
436: /* Solve for solution vector that minimizes the residual */
438: /* If it is < 0, no lgmres steps have been performed */
439: if (it < 0) {
440: VecCopy(vguess,vdest); /* VecCopy() is smart, exists immediately if vguess == vdest */
441: return(0);
442: }
444: /* so (it+1) lgmres steps HAVE been performed */
446: /* LGMRES_MOD - determine if we need to use augvecs for the soln - do not assume that
447: this is called after the total its allowed for an approx space */
448: if (lgmres->approx_constant) {
449: it_arnoldi = lgmres->max_k - lgmres->aug_ct;
450: } else {
451: it_arnoldi = lgmres->max_k - lgmres->aug_dim;
452: }
453: if (it_arnoldi >= it +1) {
454: it_aug = 0;
455: it_arnoldi = it+1;
456: } else {
457: it_aug = (it + 1) - it_arnoldi;
458: }
460: /* now it_arnoldi indicates the number of matvecs that took place */
461: lgmres->matvecs += it_arnoldi;
464: /* solve the upper triangular system - GRS is the right side and HH is
465: the upper triangular matrix - put soln in nrs */
466: if (*HH(it,it) == 0.0) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_CONV_FAILED,"HH(it,it) is identically zero; it = %D GRS(it) = %g",it,(double)PetscAbsScalar(*GRS(it)));
467: if (*HH(it,it) != 0.0) {
468: nrs[it] = *GRS(it) / *HH(it,it);
469: } else {
470: nrs[it] = 0.0;
471: }
473: for (ii=1; ii<=it; ii++) {
474: k = it - ii;
475: tt = *GRS(k);
476: for (j=k+1; j<=it; j++) tt = tt - *HH(k,j) * nrs[j];
477: nrs[k] = tt / *HH(k,k);
478: }
480: /* Accumulate the correction to the soln of the preconditioned prob. in VEC_TEMP */
481: VecSet(VEC_TEMP,0.0); /* set VEC_TEMP components to 0 */
483: /*LGMRES_MOD - if augmenting has happened we need to form the solution
484: using the augvecs */
485: if (!it_aug) { /* all its are from arnoldi */
486: VecMAXPY(VEC_TEMP,it+1,nrs,&VEC_VV(0));
487: } else { /*use aug vecs */
488: /*first do regular krylov directions */
489: VecMAXPY(VEC_TEMP,it_arnoldi,nrs,&VEC_VV(0));
490: /*now add augmented portions - add contribution of aug vectors one at a time*/
493: for (ii=0; ii<it_aug; ii++) {
494: for (jj=0; jj<lgmres->aug_dim; jj++) {
495: if (lgmres->aug_order[jj] == (ii+1)) {
496: spot = jj;
497: break; /* must have this because there will be duplicates before aug_ct = aug_dim */
498: }
499: }
500: VecAXPY(VEC_TEMP,nrs[it_arnoldi+ii],AUGVEC(spot));
501: }
502: }
503: /* now VEC_TEMP is what we want to keep for augmenting purposes - grab before the
504: preconditioner is "unwound" from right-precondtioning*/
505: VecCopy(VEC_TEMP, AUG_TEMP);
507: KSPUnwindPreconditioner(ksp,VEC_TEMP,VEC_TEMP_MATOP);
509: /* add solution to previous solution */
510: /* put updated solution into vdest.*/
511: VecCopy(vguess,vdest);
512: VecAXPY(vdest,1.0,VEC_TEMP);
513: return(0);
514: }
516: /*
518: KSPLGMRESUpdateHessenberg - Do the scalar work for the orthogonalization.
519: Return new residual.
521: input parameters:
523: . ksp - Krylov space object
524: . it - plane rotations are applied to the (it+1)th column of the
525: modified hessenberg (i.e. HH(:,it))
526: . hapend - PETSC_FALSE not happy breakdown ending.
528: output parameters:
529: . res - the new residual
531: */
534: static PetscErrorCode KSPLGMRESUpdateHessenberg(KSP ksp,PetscInt it,PetscBool hapend,PetscReal *res)535: {
536: PetscScalar *hh,*cc,*ss,tt;
537: PetscInt j;
538: KSP_LGMRES *lgmres = (KSP_LGMRES*)(ksp->data);
541: hh = HH(0,it); /* pointer to beginning of column to update - so
542: incrementing hh "steps down" the (it+1)th col of HH*/
543: cc = CC(0); /* beginning of cosine rotations */
544: ss = SS(0); /* beginning of sine rotations */
546: /* Apply all the previously computed plane rotations to the new column
547: of the Hessenberg matrix */
548: /* Note: this uses the rotation [conj(c) s ; -s c], c= cos(theta), s= sin(theta) */
550: for (j=1; j<=it; j++) {
551: tt = *hh;
552: *hh = PetscConj(*cc) * tt + *ss * *(hh+1);
553: hh++;
554: *hh = *cc++ * *hh - (*ss++ * tt);
555: /* hh, cc, and ss have all been incremented one by end of loop */
556: }
558: /*
559: compute the new plane rotation, and apply it to:
560: 1) the right-hand-side of the Hessenberg system (GRS)
561: note: it affects GRS(it) and GRS(it+1)
562: 2) the new column of the Hessenberg matrix
563: note: it affects HH(it,it) which is currently pointed to
564: by hh and HH(it+1, it) (*(hh+1))
565: thus obtaining the updated value of the residual...
566: */
568: /* compute new plane rotation */
570: if (!hapend) {
571: tt = PetscSqrtScalar(PetscConj(*hh) * *hh + PetscConj(*(hh+1)) * *(hh+1));
572: if (tt == 0.0) {
573: ksp->reason = KSP_DIVERGED_NULL;
574: return(0);
575: }
576: *cc = *hh / tt; /* new cosine value */
577: *ss = *(hh+1) / tt; /* new sine value */
579: /* apply to 1) and 2) */
580: *GRS(it+1) = -(*ss * *GRS(it));
581: *GRS(it) = PetscConj(*cc) * *GRS(it);
582: *hh = PetscConj(*cc) * *hh + *ss * *(hh+1);
584: /* residual is the last element (it+1) of right-hand side! */
585: *res = PetscAbsScalar(*GRS(it+1));
587: } else { /* happy breakdown: HH(it+1, it) = 0, therfore we don't need to apply
588: another rotation matrix (so RH doesn't change). The new residual is
589: always the new sine term times the residual from last time (GRS(it)),
590: but now the new sine rotation would be zero...so the residual should
591: be zero...so we will multiply "zero" by the last residual. This might
592: not be exactly what we want to do here -could just return "zero". */
594: *res = 0.0;
595: }
596: return(0);
597: }
599: /*
601: KSPLGMRESGetNewVectors - This routine allocates more work vectors, starting from
602: VEC_VV(it)
604: */
607: static PetscErrorCode KSPLGMRESGetNewVectors(KSP ksp,PetscInt it)608: {
609: KSP_LGMRES *lgmres = (KSP_LGMRES*)ksp->data;
610: PetscInt nwork = lgmres->nwork_alloc; /* number of work vector chunks allocated */
611: PetscInt nalloc; /* number to allocate */
613: PetscInt k;
616: nalloc = lgmres->delta_allocate; /* number of vectors to allocate
617: in a single chunk */
619: /* Adjust the number to allocate to make sure that we don't exceed the
620: number of available slots (lgmres->vecs_allocated)*/
621: if (it + VEC_OFFSET + nalloc >= lgmres->vecs_allocated) {
622: nalloc = lgmres->vecs_allocated - it - VEC_OFFSET;
623: }
624: if (!nalloc) return(0);
626: lgmres->vv_allocated += nalloc; /* vv_allocated is the number of vectors allocated */
628: /* work vectors */
629: KSPCreateVecs(ksp,nalloc,&lgmres->user_work[nwork],0,NULL);
630: PetscLogObjectParents(ksp,nalloc,lgmres->user_work[nwork]);
631: /* specify size of chunk allocated */
632: lgmres->mwork_alloc[nwork] = nalloc;
634: for (k=0; k < nalloc; k++) {
635: lgmres->vecs[it+VEC_OFFSET+k] = lgmres->user_work[nwork][k];
636: }
639: /* LGMRES_MOD - for now we are preallocating the augmentation vectors */
642: /* increment the number of work vector chunks */
643: lgmres->nwork_alloc++;
644: return(0);
645: }
647: /*
649: KSPBuildSolution_LGMRES
651: Input Parameter:
652: . ksp - the Krylov space object
653: . ptr-
655: Output Parameter:
656: . result - the solution
658: Note: this calls KSPLGMRESBuildSoln - the same function that KSPLGMRESCycle
659: calls directly.
661: */
664: PetscErrorCode KSPBuildSolution_LGMRES(KSP ksp,Vec ptr,Vec *result)665: {
666: KSP_LGMRES *lgmres = (KSP_LGMRES*)ksp->data;
670: if (!ptr) {
671: if (!lgmres->sol_temp) {
672: VecDuplicate(ksp->vec_sol,&lgmres->sol_temp);
673: PetscLogObjectParent((PetscObject)ksp,(PetscObject)lgmres->sol_temp);
674: }
675: ptr = lgmres->sol_temp;
676: }
677: if (!lgmres->nrs) {
678: /* allocate the work area */
679: PetscMalloc1(lgmres->max_k,&lgmres->nrs);
680: PetscLogObjectMemory((PetscObject)ksp,lgmres->max_k*sizeof(PetscScalar));
681: }
683: KSPLGMRESBuildSoln(lgmres->nrs,ksp->vec_sol,ptr,ksp,lgmres->it);
684: if (result) *result = ptr;
685: return(0);
686: }
690: PetscErrorCode KSPView_LGMRES(KSP ksp,PetscViewer viewer)691: {
692: KSP_LGMRES *lgmres = (KSP_LGMRES*)ksp->data;
694: PetscBool iascii;
697: KSPView_GMRES(ksp,viewer);
698: PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
699: if (iascii) {
700: /*LGMRES_MOD */
701: PetscViewerASCIIPrintf(viewer," LGMRES: aug. dimension=%D\n",lgmres->aug_dim);
702: if (lgmres->approx_constant) {
703: PetscViewerASCIIPrintf(viewer," LGMRES: approx. space size was kept constant.\n");
704: }
705: PetscViewerASCIIPrintf(viewer," LGMRES: number of matvecs=%D\n",lgmres->matvecs);
706: }
707: return(0);
708: }
712: PetscErrorCode KSPSetFromOptions_LGMRES(PetscOptionItems *PetscOptionsObject,KSP ksp)713: {
715: PetscInt aug;
716: KSP_LGMRES *lgmres = (KSP_LGMRES*) ksp->data;
717: PetscBool flg = PETSC_FALSE;
720: KSPSetFromOptions_GMRES(PetscOptionsObject,ksp);
721: PetscOptionsHead(PetscOptionsObject,"KSP LGMRES Options");
722: PetscOptionsBool("-ksp_lgmres_constant","Use constant approx. space size","KSPGMRESSetConstant",lgmres->approx_constant,&lgmres->approx_constant,NULL);
723: PetscOptionsInt("-ksp_lgmres_augment","Number of error approximations to augment the Krylov space with","KSPLGMRESSetAugDim",lgmres->aug_dim,&aug,&flg);
724: if (flg) { KSPLGMRESSetAugDim(ksp,aug); }
725: PetscOptionsTail();
726: return(0);
727: }
729: /*functions for extra lgmres options here*/
732: static PetscErrorCode KSPLGMRESSetConstant_LGMRES(KSP ksp)733: {
734: KSP_LGMRES *lgmres = (KSP_LGMRES*)ksp->data;
737: lgmres->approx_constant = PETSC_TRUE;
738: return(0);
739: }
743: static PetscErrorCode KSPLGMRESSetAugDim_LGMRES(KSP ksp,PetscInt aug_dim)744: {
745: KSP_LGMRES *lgmres = (KSP_LGMRES*)ksp->data;
748: if (aug_dim < 0) SETERRQ(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_OUTOFRANGE,"Augmentation dimension must be positive");
749: if (aug_dim > (lgmres->max_k -1)) SETERRQ(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_OUTOFRANGE,"Augmentation dimension must be <= (restart size-1)");
750: lgmres->aug_dim = aug_dim;
751: return(0);
752: }
754: /* end new lgmres functions */
756: /*MC
757: KSPLGMRES - Augments the standard GMRES approximation space with approximations to
758: the error from previous restart cycles.
760: Options Database Keys:
761: + -ksp_gmres_restart <restart> - total approximation space size (Krylov directions + error approximations)
762: . -ksp_gmres_haptol <tol> - sets the tolerance for "happy ending" (exact convergence)
763: . -ksp_gmres_preallocate - preallocate all the Krylov search directions initially (otherwise groups of
764: vectors are allocated as needed)
765: . -ksp_gmres_classicalgramschmidt - use classical (unmodified) Gram-Schmidt to orthogonalize against the Krylov space (fast) (the default)
766: . -ksp_gmres_modifiedgramschmidt - use modified Gram-Schmidt in the orthogonalization (more stable, but slower)
767: . -ksp_gmres_cgs_refinement_type <never,ifneeded,always> - determine if iterative refinement is used to increase the
768: stability of the classical Gram-Schmidt orthogonalization.
769: . -ksp_gmres_krylov_monitor - plot the Krylov space generated
770: . -ksp_lgmres_augment <k> - number of error approximations to augment the Krylov space with
771: - -ksp_lgmres_constant - use a constant approx. space size (only affects restart cycles < num. error approx.(k), i.e. the first k restarts)
773: To run LGMRES(m, k) as described in the above paper, use:
774: -ksp_gmres_restart <m+k>
775: -ksp_lgmres_augment <k>
777: Level: beginner
779: Notes: Supports both left and right preconditioning, but not symmetric.
781: References:
782: . 1. - A. H. Baker, E.R. Jessup, and T.A. Manteuffel. A technique for accelerating the convergence of restarted GMRES. SIAM Journal on Matrix Analysis and Applications, 26 (2005).
784: Developer Notes: This object is subclassed off of KSPGMRES786: Contributed by: Allison Baker
788: .seealso: KSPCreate(), KSPSetType(), KSPType (for list of available types), KSP, KSPFGMRES, KSPGMRES,
789: KSPGMRESSetRestart(), KSPGMRESSetHapTol(), KSPGMRESSetPreAllocateVectors(), KSPGMRESSetOrthogonalization(), KSPGMRESGetOrthogonalization(),
790: KSPGMRESClassicalGramSchmidtOrthogonalization(), KSPGMRESModifiedGramSchmidtOrthogonalization(),
791: KSPGMRESCGSRefinementType, KSPGMRESSetCGSRefinementType(), KSPGMRESGetCGSRefinementType(), KSPGMRESMonitorKrylov(), KSPLGMRESSetAugDim(),
792: KSPGMRESSetConstant()
794: M*/
798: PETSC_EXTERN PetscErrorCode KSPCreate_LGMRES(KSP ksp)799: {
800: KSP_LGMRES *lgmres;
804: PetscNewLog(ksp,&lgmres);
806: ksp->data = (void*)lgmres;
807: ksp->ops->buildsolution = KSPBuildSolution_LGMRES;
809: ksp->ops->setup = KSPSetUp_LGMRES;
810: ksp->ops->solve = KSPSolve_LGMRES;
811: ksp->ops->destroy = KSPDestroy_LGMRES;
812: ksp->ops->view = KSPView_LGMRES;
813: ksp->ops->setfromoptions = KSPSetFromOptions_LGMRES;
814: ksp->ops->computeextremesingularvalues = KSPComputeExtremeSingularValues_GMRES;
815: ksp->ops->computeeigenvalues = KSPComputeEigenvalues_GMRES;
817: KSPSetSupportedNorm(ksp,KSP_NORM_PRECONDITIONED,PC_LEFT,3);
818: KSPSetSupportedNorm(ksp,KSP_NORM_UNPRECONDITIONED,PC_RIGHT,2);
820: PetscObjectComposeFunction((PetscObject)ksp,"KSPGMRESSetPreAllocateVectors_C",KSPGMRESSetPreAllocateVectors_GMRES);
821: PetscObjectComposeFunction((PetscObject)ksp,"KSPGMRESSetOrthogonalization_C",KSPGMRESSetOrthogonalization_GMRES);
822: PetscObjectComposeFunction((PetscObject)ksp,"KSPGMRESGetOrthogonalization_C",KSPGMRESGetOrthogonalization_GMRES);
823: PetscObjectComposeFunction((PetscObject)ksp,"KSPGMRESSetRestart_C",KSPGMRESSetRestart_GMRES);
824: PetscObjectComposeFunction((PetscObject)ksp,"KSPGMRESGetRestart_C",KSPGMRESGetRestart_GMRES);
825: PetscObjectComposeFunction((PetscObject)ksp,"KSPGMRESSetHapTol_C",KSPGMRESSetHapTol_GMRES);
826: PetscObjectComposeFunction((PetscObject)ksp,"KSPGMRESSetCGSRefinementType_C",KSPGMRESSetCGSRefinementType_GMRES);
827: PetscObjectComposeFunction((PetscObject)ksp,"KSPGMRESGetCGSRefinementType_C",KSPGMRESGetCGSRefinementType_GMRES);
829: /*LGMRES_MOD add extra functions here - like the one to set num of aug vectors */
830: PetscObjectComposeFunction((PetscObject)ksp,"KSPLGMRESSetConstant_C",KSPLGMRESSetConstant_LGMRES);
831: PetscObjectComposeFunction((PetscObject)ksp,"KSPLGMRESSetAugDim_C",KSPLGMRESSetAugDim_LGMRES);
834: /*defaults */
835: lgmres->haptol = 1.0e-30;
836: lgmres->q_preallocate = 0;
837: lgmres->delta_allocate = LGMRES_DELTA_DIRECTIONS;
838: lgmres->orthog = KSPGMRESClassicalGramSchmidtOrthogonalization;
839: lgmres->nrs = 0;
840: lgmres->sol_temp = 0;
841: lgmres->max_k = LGMRES_DEFAULT_MAXK;
842: lgmres->Rsvd = 0;
843: lgmres->cgstype = KSP_GMRES_CGS_REFINE_NEVER;
844: lgmres->orthogwork = 0;
846: /*LGMRES_MOD - new defaults */
847: lgmres->aug_dim = LGMRES_DEFAULT_AUGDIM;
848: lgmres->aug_ct = 0; /* start with no aug vectors */
849: lgmres->approx_constant = PETSC_FALSE;
850: lgmres->matvecs = 0;
851: return(0);
852: }