Actual source code: asm.c

petsc-3.6.1 2015-07-22
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  2: /*
  3:   This file defines an additive Schwarz preconditioner for any Mat implementation.

  5:   Note that each processor may have any number of subdomains. But in order to
  6:   deal easily with the VecScatter(), we treat each processor as if it has the
  7:   same number of subdomains.

  9:        n - total number of true subdomains on all processors
 10:        n_local_true - actual number of subdomains on this processor
 11:        n_local = maximum over all processors of n_local_true
 12: */
 13: #include <petsc/private/pcimpl.h>     /*I "petscpc.h" I*/
 14: #include <petscdm.h>

 16: typedef struct {
 17:   PetscInt   n, n_local, n_local_true;
 18:   PetscInt   overlap;             /* overlap requested by user */
 19:   KSP        *ksp;                /* linear solvers for each block */
 20:   VecScatter *restriction;        /* mapping from global to subregion */
 21:   VecScatter *localization;       /* mapping from overlapping to non-overlapping subregion */
 22:   VecScatter *prolongation;       /* mapping from subregion to global */
 23:   Vec        *x,*y,*y_local;      /* work vectors */
 24:   IS         *is;                 /* index set that defines each overlapping subdomain */
 25:   IS         *is_local;           /* index set that defines each non-overlapping subdomain, may be NULL */
 26:   Mat        *mat,*pmat;          /* mat is not currently used */
 27:   PCASMType  type;                /* use reduced interpolation, restriction or both */
 28:   PetscBool  type_set;            /* if user set this value (so won't change it for symmetric problems) */
 29:   PetscBool  same_local_solves;   /* flag indicating whether all local solvers are same */
 30:   PetscBool  sort_indices;        /* flag to sort subdomain indices */
 31:   PetscBool  dm_subdomains;       /* whether DM is allowed to define subdomains */
 32:   PCCompositeType loctype;        /* the type of composition for local solves */
 33: } PC_ASM;

 37: static PetscErrorCode PCView_ASM(PC pc,PetscViewer viewer)
 38: {
 39:   PC_ASM         *osm = (PC_ASM*)pc->data;
 41:   PetscMPIInt    rank;
 42:   PetscInt       i,bsz;
 43:   PetscBool      iascii,isstring;
 44:   PetscViewer    sviewer;

 47:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
 48:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);
 49:   if (iascii) {
 50:     char overlaps[256] = "user-defined overlap",blocks[256] = "total subdomain blocks not yet set";
 51:     if (osm->overlap >= 0) {PetscSNPrintf(overlaps,sizeof(overlaps),"amount of overlap = %D",osm->overlap);}
 52:     if (osm->n > 0) {PetscSNPrintf(blocks,sizeof(blocks),"total subdomain blocks = %D",osm->n);}
 53:     PetscViewerASCIIPrintf(viewer,"  Additive Schwarz: %s, %s\n",blocks,overlaps);
 54:     PetscViewerASCIIPrintf(viewer,"  Additive Schwarz: restriction/interpolation type - %s\n",PCASMTypes[osm->type]);
 55:     if (osm->loctype != PC_COMPOSITE_ADDITIVE) {PetscViewerASCIIPrintf(viewer,"  Additive Schwarz: local solve composition type - %s\n",PCCompositeTypes[osm->loctype]);}
 56:     MPI_Comm_rank(PetscObjectComm((PetscObject)pc),&rank);
 57:     if (osm->same_local_solves) {
 58:       if (osm->ksp) {
 59:         PetscViewerASCIIPrintf(viewer,"  Local solve is same for all blocks, in the following KSP and PC objects:\n");
 60:         PetscViewerGetSingleton(viewer,&sviewer);
 61:         if (!rank) {
 62:           PetscViewerASCIIPushTab(viewer);
 63:           KSPView(osm->ksp[0],sviewer);
 64:           PetscViewerASCIIPopTab(viewer);
 65:         }
 66:         PetscViewerRestoreSingleton(viewer,&sviewer);
 67:       }
 68:     } else {
 69:       PetscViewerASCIISynchronizedAllow(viewer,PETSC_TRUE);
 70:       PetscViewerASCIISynchronizedPrintf(viewer,"  [%d] number of local blocks = %D\n",(int)rank,osm->n_local_true);
 71:       PetscViewerFlush(viewer);
 72:       PetscViewerASCIIPrintf(viewer,"  Local solve info for each block is in the following KSP and PC objects:\n");
 73:       PetscViewerASCIIPushTab(viewer);
 74:       PetscViewerASCIIPrintf(viewer,"- - - - - - - - - - - - - - - - - -\n");
 75:       PetscViewerGetSingleton(viewer,&sviewer);
 76:       for (i=0; i<osm->n_local_true; i++) {
 77:         ISGetLocalSize(osm->is[i],&bsz);
 78:         PetscViewerASCIISynchronizedPrintf(sviewer,"[%d] local block number %D, size = %D\n",(int)rank,i,bsz);
 79:         KSPView(osm->ksp[i],sviewer);
 80:         PetscViewerASCIISynchronizedPrintf(sviewer,"- - - - - - - - - - - - - - - - - -\n");
 81:       }
 82:       PetscViewerRestoreSingleton(viewer,&sviewer);
 83:       PetscViewerASCIIPopTab(viewer);
 84:       PetscViewerFlush(viewer);
 85:       PetscViewerASCIISynchronizedAllow(viewer,PETSC_FALSE);
 86:     }
 87:   } else if (isstring) {
 88:     PetscViewerStringSPrintf(viewer," blocks=%D, overlap=%D, type=%s",osm->n,osm->overlap,PCASMTypes[osm->type]);
 89:     PetscViewerGetSingleton(viewer,&sviewer);
 90:     if (osm->ksp) {KSPView(osm->ksp[0],sviewer);}
 91:     PetscViewerRestoreSingleton(viewer,&sviewer);
 92:   }
 93:   return(0);
 94: }

 98: static PetscErrorCode PCASMPrintSubdomains(PC pc)
 99: {
100:   PC_ASM         *osm = (PC_ASM*)pc->data;
101:   const char     *prefix;
102:   char           fname[PETSC_MAX_PATH_LEN+1];
103:   PetscViewer    viewer, sviewer;
104:   char           *s;
105:   PetscInt       i,j,nidx;
106:   const PetscInt *idx;
107:   PetscMPIInt    rank, size;

111:   MPI_Comm_size(PetscObjectComm((PetscObject)pc), &size);
112:   MPI_Comm_rank(PetscObjectComm((PetscObject)pc), &rank);
113:   PCGetOptionsPrefix(pc,&prefix);
114:   PetscOptionsGetString(prefix,"-pc_asm_print_subdomains",fname,PETSC_MAX_PATH_LEN,NULL);
115:   if (fname[0] == 0) { PetscStrcpy(fname,"stdout"); };
116:   PetscViewerASCIIOpen(PetscObjectComm((PetscObject)pc),fname,&viewer);
117:   for (i=0; i<osm->n_local; i++) {
118:     if (i < osm->n_local_true) {
119:       ISGetLocalSize(osm->is[i],&nidx);
120:       ISGetIndices(osm->is[i],&idx);
121:       /* Print to a string viewer; no more than 15 characters per index plus 512 char for the header.*/
122:       PetscMalloc1(16*(nidx+1)+512, &s);
123:       PetscViewerStringOpen(PETSC_COMM_SELF, s, 16*(nidx+1)+512, &sviewer);
124:       PetscViewerStringSPrintf(sviewer, "[%D:%D] Subdomain %D with overlap:\n", rank, size, i);
125:       for (j=0; j<nidx; j++) {
126:         PetscViewerStringSPrintf(sviewer,"%D ",idx[j]);
127:       }
128:       ISRestoreIndices(osm->is[i],&idx);
129:       PetscViewerStringSPrintf(sviewer,"\n");
130:       PetscViewerDestroy(&sviewer);
131:       PetscViewerASCIISynchronizedAllow(viewer, PETSC_TRUE);
132:       PetscViewerASCIISynchronizedPrintf(viewer, s);
133:       PetscViewerFlush(viewer);
134:       PetscViewerASCIISynchronizedAllow(viewer, PETSC_FALSE);
135:       PetscFree(s);
136:       if (osm->is_local) {
137:         /* Print to a string viewer; no more than 15 characters per index plus 512 char for the header.*/
138:         PetscMalloc1(16*(nidx+1)+512, &s);
139:         PetscViewerStringOpen(PETSC_COMM_SELF, s, 16*(nidx+1)+512, &sviewer);
140:         PetscViewerStringSPrintf(sviewer, "[%D:%D] Subdomain %D without overlap:\n", rank, size, i);
141:         ISGetLocalSize(osm->is_local[i],&nidx);
142:         ISGetIndices(osm->is_local[i],&idx);
143:         for (j=0; j<nidx; j++) {
144:           PetscViewerStringSPrintf(sviewer,"%D ",idx[j]);
145:         }
146:         ISRestoreIndices(osm->is_local[i],&idx);
147:         PetscViewerStringSPrintf(sviewer,"\n");
148:         PetscViewerDestroy(&sviewer);
149:         PetscViewerASCIISynchronizedAllow(viewer, PETSC_TRUE);
150:         PetscViewerASCIISynchronizedPrintf(viewer, s);
151:         PetscViewerFlush(viewer);
152:         PetscViewerASCIISynchronizedAllow(viewer, PETSC_FALSE);
153:         PetscFree(s);
154:       }
155:     } else {
156:       /* Participate in collective viewer calls. */
157:       PetscViewerASCIISynchronizedAllow(viewer, PETSC_TRUE);
158:       PetscViewerFlush(viewer);
159:       PetscViewerASCIISynchronizedAllow(viewer, PETSC_FALSE);
160:       /* Assume either all ranks have is_local or none do. */
161:       if (osm->is_local) {
162:         PetscViewerASCIISynchronizedAllow(viewer, PETSC_TRUE);
163:         PetscViewerFlush(viewer);
164:         PetscViewerASCIISynchronizedAllow(viewer, PETSC_FALSE);
165:       }
166:     }
167:   }
168:   PetscViewerFlush(viewer);
169:   PetscViewerDestroy(&viewer);
170:   return(0);
171: }

175: static PetscErrorCode PCSetUp_ASM(PC pc)
176: {
177:   PC_ASM         *osm = (PC_ASM*)pc->data;
179:   PetscBool      symset,flg;
180:   PetscInt       i,m,m_local;
181:   MatReuse       scall = MAT_REUSE_MATRIX;
182:   IS             isl;
183:   KSP            ksp;
184:   PC             subpc;
185:   const char     *prefix,*pprefix;
186:   Vec            vec;
187:   DM             *domain_dm = NULL;

190:   if (!pc->setupcalled) {

192:     if (!osm->type_set) {
193:       MatIsSymmetricKnown(pc->pmat,&symset,&flg);
194:       if (symset && flg) osm->type = PC_ASM_BASIC;
195:     }

197:     /* Note: if subdomains have been set either via PCASMSetTotalSubdomains() or via PCASMSetLocalSubdomains(), osm->n_local_true will not be PETSC_DECIDE */
198:     if (osm->n_local_true == PETSC_DECIDE) {
199:       /* no subdomains given */
200:       /* try pc->dm first, if allowed */
201:       if (osm->dm_subdomains && pc->dm) {
202:         PetscInt  num_domains, d;
203:         char      **domain_names;
204:         IS        *inner_domain_is, *outer_domain_is;
205:         DMCreateDomainDecomposition(pc->dm, &num_domains, &domain_names, &inner_domain_is, &outer_domain_is, &domain_dm);
206:         if (num_domains) {
207:           PCASMSetLocalSubdomains(pc, num_domains, outer_domain_is, inner_domain_is);
208:         }
209:         for (d = 0; d < num_domains; ++d) {
210:           if (domain_names)    {PetscFree(domain_names[d]);}
211:           if (inner_domain_is) {ISDestroy(&inner_domain_is[d]);}
212:           if (outer_domain_is) {ISDestroy(&outer_domain_is[d]);}
213:         }
214:         PetscFree(domain_names);
215:         PetscFree(inner_domain_is);
216:         PetscFree(outer_domain_is);
217:       }
218:       if (osm->n_local_true == PETSC_DECIDE) {
219:         /* still no subdomains; use one subdomain per processor */
220:         osm->n_local_true = 1;
221:       }
222:     }
223:     { /* determine the global and max number of subdomains */
224:       struct {PetscInt max,sum;} inwork,outwork;
225:       inwork.max   = osm->n_local_true;
226:       inwork.sum   = osm->n_local_true;
227:       MPI_Allreduce(&inwork,&outwork,1,MPIU_2INT,PetscMaxSum_Op,PetscObjectComm((PetscObject)pc));
228:       osm->n_local = outwork.max;
229:       osm->n       = outwork.sum;
230:     }
231:     if (!osm->is) { /* create the index sets */
232:       PCASMCreateSubdomains(pc->pmat,osm->n_local_true,&osm->is);
233:     }
234:     if (osm->n_local_true > 1 && !osm->is_local) {
235:       PetscMalloc1(osm->n_local_true,&osm->is_local);
236:       for (i=0; i<osm->n_local_true; i++) {
237:         if (osm->overlap > 0) { /* With positive overlap, osm->is[i] will be modified */
238:           ISDuplicate(osm->is[i],&osm->is_local[i]);
239:           ISCopy(osm->is[i],osm->is_local[i]);
240:         } else {
241:           PetscObjectReference((PetscObject)osm->is[i]);
242:           osm->is_local[i] = osm->is[i];
243:         }
244:       }
245:     }
246:     PCGetOptionsPrefix(pc,&prefix);
247:     flg  = PETSC_FALSE;
248:     PetscOptionsGetBool(prefix,"-pc_asm_print_subdomains",&flg,NULL);
249:     if (flg) { PCASMPrintSubdomains(pc); }

251:     if (osm->overlap > 0) {
252:       /* Extend the "overlapping" regions by a number of steps */
253:       MatIncreaseOverlap(pc->pmat,osm->n_local_true,osm->is,osm->overlap);
254:     }
255:     if (osm->sort_indices) {
256:       for (i=0; i<osm->n_local_true; i++) {
257:         ISSort(osm->is[i]);
258:         if (osm->is_local) {
259:           ISSort(osm->is_local[i]);
260:         }
261:       }
262:     }
263:     /* Create the local work vectors and scatter contexts */
264:     MatCreateVecs(pc->pmat,&vec,0);
265:     PetscMalloc1(osm->n_local,&osm->restriction);
266:     if (osm->is_local) {PetscMalloc1(osm->n_local,&osm->localization);}
267:     PetscMalloc1(osm->n_local,&osm->prolongation);
268:     PetscMalloc1(osm->n_local,&osm->x);
269:     PetscMalloc1(osm->n_local,&osm->y);
270:     PetscMalloc1(osm->n_local,&osm->y_local);
271:     for (i=0; i<osm->n_local_true; ++i) {
272:       ISGetLocalSize(osm->is[i],&m);
273:       VecCreateSeq(PETSC_COMM_SELF,m,&osm->x[i]);
274:       ISCreateStride(PETSC_COMM_SELF,m,0,1,&isl);
275:       VecScatterCreate(vec,osm->is[i],osm->x[i],isl,&osm->restriction[i]);
276:       ISDestroy(&isl);
277:       VecDuplicate(osm->x[i],&osm->y[i]);
278:       if (osm->is_local) {
279:         ISLocalToGlobalMapping ltog;
280:         IS                     isll;
281:         const PetscInt         *idx_local;
282:         PetscInt               *idx,nout;

284:         ISLocalToGlobalMappingCreateIS(osm->is[i],&ltog);
285:         ISGetLocalSize(osm->is_local[i],&m_local);
286:         ISGetIndices(osm->is_local[i], &idx_local);
287:         PetscMalloc1(m_local,&idx);
288:         ISGlobalToLocalMappingApply(ltog,IS_GTOLM_DROP,m_local,idx_local,&nout,idx);
289:         ISLocalToGlobalMappingDestroy(&ltog);
290:         if (nout != m_local) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"is_local not a subset of is");
291:         ISRestoreIndices(osm->is_local[i], &idx_local);
292:         ISCreateGeneral(PETSC_COMM_SELF,m_local,idx,PETSC_OWN_POINTER,&isll);
293:         ISCreateStride(PETSC_COMM_SELF,m_local,0,1,&isl);
294:         VecCreateSeq(PETSC_COMM_SELF,m_local,&osm->y_local[i]);
295:         VecScatterCreate(osm->y[i],isll,osm->y_local[i],isl,&osm->localization[i]);
296:         ISDestroy(&isll);

298:         VecScatterCreate(vec,osm->is_local[i],osm->y_local[i],isl,&osm->prolongation[i]);
299:         ISDestroy(&isl);
300:       } else {
301:         VecGetLocalSize(vec,&m_local);

303:         osm->y_local[i] = osm->y[i];

305:         PetscObjectReference((PetscObject) osm->y[i]);

307:         osm->prolongation[i] = osm->restriction[i];

309:         PetscObjectReference((PetscObject) osm->restriction[i]);
310:       }
311:     }
312:     for (i=osm->n_local_true; i<osm->n_local; i++) {
313:       VecCreateSeq(PETSC_COMM_SELF,0,&osm->x[i]);
314:       VecDuplicate(osm->x[i],&osm->y[i]);
315:       VecDuplicate(osm->x[i],&osm->y_local[i]);
316:       ISCreateStride(PETSC_COMM_SELF,0,0,1,&isl);
317:       VecScatterCreate(vec,isl,osm->x[i],isl,&osm->restriction[i]);
318:       if (osm->is_local) {
319:         VecScatterCreate(osm->y[i],isl,osm->y_local[i],isl,&osm->localization[i]);
320:         VecScatterCreate(vec,isl,osm->x[i],isl,&osm->prolongation[i]);
321:       } else {
322:         osm->prolongation[i] = osm->restriction[i];
323:         PetscObjectReference((PetscObject) osm->restriction[i]);
324:       }
325:       ISDestroy(&isl);
326:     }
327:     VecDestroy(&vec);

329:     if (!osm->ksp) {
330:       /* Create the local solvers */
331:       PetscMalloc1(osm->n_local_true,&osm->ksp);
332:       if (domain_dm) {
333:         PetscInfo(pc,"Setting up ASM subproblems using the embedded DM\n");
334:       }
335:       for (i=0; i<osm->n_local_true; i++) {
336:         KSPCreate(PETSC_COMM_SELF,&ksp);
337:         KSPSetErrorIfNotConverged(ksp,pc->erroriffailure);
338:         PetscLogObjectParent((PetscObject)pc,(PetscObject)ksp);
339:         PetscObjectIncrementTabLevel((PetscObject)ksp,(PetscObject)pc,1);
340:         KSPSetType(ksp,KSPPREONLY);
341:         KSPGetPC(ksp,&subpc);
342:         PCGetOptionsPrefix(pc,&prefix);
343:         KSPSetOptionsPrefix(ksp,prefix);
344:         KSPAppendOptionsPrefix(ksp,"sub_");
345:         if (domain_dm) {
346:           KSPSetDM(ksp, domain_dm[i]);
347:           KSPSetDMActive(ksp, PETSC_FALSE);
348:           DMDestroy(&domain_dm[i]);
349:         }
350:         osm->ksp[i] = ksp;
351:       }
352:       if (domain_dm) {
353:         PetscFree(domain_dm);
354:       }
355:     }
356:     scall = MAT_INITIAL_MATRIX;
357:   } else {
358:     /*
359:        Destroy the blocks from the previous iteration
360:     */
361:     if (pc->flag == DIFFERENT_NONZERO_PATTERN) {
362:       MatDestroyMatrices(osm->n_local_true,&osm->pmat);
363:       scall = MAT_INITIAL_MATRIX;
364:     }
365:   }

367:   /*
368:      Extract out the submatrices
369:   */
370:   MatGetSubMatrices(pc->pmat,osm->n_local_true,osm->is,osm->is,scall,&osm->pmat);
371:   if (scall == MAT_INITIAL_MATRIX) {
372:     PetscObjectGetOptionsPrefix((PetscObject)pc->pmat,&pprefix);
373:     for (i=0; i<osm->n_local_true; i++) {
374:       PetscLogObjectParent((PetscObject)pc,(PetscObject)osm->pmat[i]);
375:       PetscObjectSetOptionsPrefix((PetscObject)osm->pmat[i],pprefix);
376:     }
377:   }

379:   /* Return control to the user so that the submatrices can be modified (e.g., to apply
380:      different boundary conditions for the submatrices than for the global problem) */
381:   PCModifySubMatrices(pc,osm->n_local_true,osm->is,osm->is,osm->pmat,pc->modifysubmatricesP);

383:   /*
384:      Loop over subdomains putting them into local ksp
385:   */
386:   for (i=0; i<osm->n_local_true; i++) {
387:     KSPSetOperators(osm->ksp[i],osm->pmat[i],osm->pmat[i]);
388:     if (!pc->setupcalled) {
389:       KSPSetFromOptions(osm->ksp[i]);
390:     }
391:   }
392:   return(0);
393: }

397: static PetscErrorCode PCSetUpOnBlocks_ASM(PC pc)
398: {
399:   PC_ASM         *osm = (PC_ASM*)pc->data;
401:   PetscInt       i;

404:   for (i=0; i<osm->n_local_true; i++) {
405:     KSPSetUp(osm->ksp[i]);
406:   }
407:   return(0);
408: }

412: static PetscErrorCode PCApply_ASM(PC pc,Vec x,Vec y)
413: {
414:   PC_ASM         *osm = (PC_ASM*)pc->data;
416:   PetscInt       i,n_local = osm->n_local,n_local_true = osm->n_local_true;
417:   ScatterMode    forward = SCATTER_FORWARD,reverse = SCATTER_REVERSE;

420:   /*
421:      Support for limiting the restriction or interpolation to only local
422:      subdomain values (leaving the other values 0).
423:   */
424:   if (!(osm->type & PC_ASM_RESTRICT)) {
425:     forward = SCATTER_FORWARD_LOCAL;
426:     /* have to zero the work RHS since scatter may leave some slots empty */
427:     for (i=0; i<n_local_true; i++) {
428:       VecZeroEntries(osm->x[i]);
429:     }
430:   }
431:   if (!(osm->type & PC_ASM_INTERPOLATE)) reverse = SCATTER_REVERSE_LOCAL;

433:   switch (osm->loctype)
434:   {
435:   case PC_COMPOSITE_ADDITIVE:
436:     for (i=0; i<n_local; i++) {
437:       VecScatterBegin(osm->restriction[i],x,osm->x[i],INSERT_VALUES,forward);
438:     }
439:     VecZeroEntries(y);
440:     /* do the local solves */
441:     for (i=0; i<n_local_true; i++) {
442:       VecScatterEnd(osm->restriction[i],x,osm->x[i],INSERT_VALUES,forward);
443:       KSPSolve(osm->ksp[i],osm->x[i],osm->y[i]);
444:       if (osm->localization) {
445:         VecScatterBegin(osm->localization[i],osm->y[i],osm->y_local[i],INSERT_VALUES,forward);
446:         VecScatterEnd(osm->localization[i],osm->y[i],osm->y_local[i],INSERT_VALUES,forward);
447:       }
448:       VecScatterBegin(osm->prolongation[i],osm->y_local[i],y,ADD_VALUES,reverse);
449:     }
450:     /* handle the rest of the scatters that do not have local solves */
451:     for (i=n_local_true; i<n_local; i++) {
452:       VecScatterEnd(osm->restriction[i],x,osm->x[i],INSERT_VALUES,forward);
453:       VecScatterBegin(osm->prolongation[i],osm->y_local[i],y,ADD_VALUES,reverse);
454:     }
455:     for (i=0; i<n_local; i++) {
456:       VecScatterEnd(osm->prolongation[i],osm->y_local[i],y,ADD_VALUES,reverse);
457:     }
458:     break;
459:   case PC_COMPOSITE_MULTIPLICATIVE:
460:     VecZeroEntries(y);
461:     /* do the local solves */
462:     for (i = 0; i < n_local_true; ++i) {
463:       if (i > 0) {
464:         /* Update initial guess */
465:         VecScatterBegin(osm->restriction[i], y, osm->y[i], INSERT_VALUES, forward);
466:         VecScatterEnd(osm->restriction[i], y, osm->y[i], INSERT_VALUES, forward);
467:         MatMult(osm->pmat[i], osm->y[i], osm->x[i]);
468:         VecScale(osm->x[i], -1.0);
469:       } else {
470:         VecZeroEntries(osm->x[i]);
471:       }
472:       VecScatterBegin(osm->restriction[i], x, osm->x[i], ADD_VALUES, forward);
473:       VecScatterEnd(osm->restriction[i], x, osm->x[i], ADD_VALUES, forward);
474:       KSPSolve(osm->ksp[i], osm->x[i], osm->y[i]);
475:       if (osm->localization) {
476:         VecScatterBegin(osm->localization[i], osm->y[i], osm->y_local[i], INSERT_VALUES, forward);
477:         VecScatterEnd(osm->localization[i], osm->y[i], osm->y_local[i], INSERT_VALUES, forward);
478:       }
479:       VecScatterBegin(osm->prolongation[i], osm->y_local[i], y, ADD_VALUES, reverse);
480:       VecScatterEnd(osm->prolongation[i], osm->y_local[i], y, ADD_VALUES, reverse);
481:     }
482:     /* handle the rest of the scatters that do not have local solves */
483:     for (i = n_local_true; i < n_local; ++i) {
484:       VecScatterBegin(osm->restriction[i], x, osm->x[i], INSERT_VALUES, forward);
485:       VecScatterEnd(osm->restriction[i], x, osm->x[i], INSERT_VALUES, forward);
486:       VecScatterBegin(osm->prolongation[i], osm->y_local[i], y, ADD_VALUES, reverse);
487:       VecScatterEnd(osm->prolongation[i], osm->y_local[i], y, ADD_VALUES, reverse);
488:     }
489:     break;
490:   default: SETERRQ1(PetscObjectComm((PetscObject) pc), PETSC_ERR_ARG_WRONG, "Invalid local composition type: %s", PCCompositeTypes[osm->loctype]);
491:   }
492:   return(0);
493: }

497: static PetscErrorCode PCApplyTranspose_ASM(PC pc,Vec x,Vec y)
498: {
499:   PC_ASM         *osm = (PC_ASM*)pc->data;
501:   PetscInt       i,n_local = osm->n_local,n_local_true = osm->n_local_true;
502:   ScatterMode    forward = SCATTER_FORWARD,reverse = SCATTER_REVERSE;

505:   /*
506:      Support for limiting the restriction or interpolation to only local
507:      subdomain values (leaving the other values 0).

509:      Note: these are reversed from the PCApply_ASM() because we are applying the
510:      transpose of the three terms
511:   */
512:   if (!(osm->type & PC_ASM_INTERPOLATE)) {
513:     forward = SCATTER_FORWARD_LOCAL;
514:     /* have to zero the work RHS since scatter may leave some slots empty */
515:     for (i=0; i<n_local_true; i++) {
516:       VecZeroEntries(osm->x[i]);
517:     }
518:   }
519:   if (!(osm->type & PC_ASM_RESTRICT)) reverse = SCATTER_REVERSE_LOCAL;

521:   for (i=0; i<n_local; i++) {
522:     VecScatterBegin(osm->restriction[i],x,osm->x[i],INSERT_VALUES,forward);
523:   }
524:   VecZeroEntries(y);
525:   /* do the local solves */
526:   for (i=0; i<n_local_true; i++) {
527:     VecScatterEnd(osm->restriction[i],x,osm->x[i],INSERT_VALUES,forward);
528:     KSPSolveTranspose(osm->ksp[i],osm->x[i],osm->y[i]);
529:     if (osm->localization) {
530:       VecScatterBegin(osm->localization[i],osm->y[i],osm->y_local[i],INSERT_VALUES,forward);
531:       VecScatterEnd(osm->localization[i],osm->y[i],osm->y_local[i],INSERT_VALUES,forward);
532:     }
533:     VecScatterBegin(osm->prolongation[i],osm->y_local[i],y,ADD_VALUES,reverse);
534:   }
535:   /* handle the rest of the scatters that do not have local solves */
536:   for (i=n_local_true; i<n_local; i++) {
537:     VecScatterEnd(osm->restriction[i],x,osm->x[i],INSERT_VALUES,forward);
538:     VecScatterBegin(osm->prolongation[i],osm->y_local[i],y,ADD_VALUES,reverse);
539:   }
540:   for (i=0; i<n_local; i++) {
541:     VecScatterEnd(osm->prolongation[i],osm->y_local[i],y,ADD_VALUES,reverse);
542:   }
543:   return(0);
544: }

548: static PetscErrorCode PCReset_ASM(PC pc)
549: {
550:   PC_ASM         *osm = (PC_ASM*)pc->data;
552:   PetscInt       i;

555:   if (osm->ksp) {
556:     for (i=0; i<osm->n_local_true; i++) {
557:       KSPReset(osm->ksp[i]);
558:     }
559:   }
560:   if (osm->pmat) {
561:     if (osm->n_local_true > 0) {
562:       MatDestroyMatrices(osm->n_local_true,&osm->pmat);
563:     }
564:   }
565:   if (osm->restriction) {
566:     for (i=0; i<osm->n_local; i++) {
567:       VecScatterDestroy(&osm->restriction[i]);
568:       if (osm->localization) {VecScatterDestroy(&osm->localization[i]);}
569:       VecScatterDestroy(&osm->prolongation[i]);
570:       VecDestroy(&osm->x[i]);
571:       VecDestroy(&osm->y[i]);
572:       VecDestroy(&osm->y_local[i]);
573:     }
574:     PetscFree(osm->restriction);
575:     if (osm->localization) {PetscFree(osm->localization);}
576:     PetscFree(osm->prolongation);
577:     PetscFree(osm->x);
578:     PetscFree(osm->y);
579:     PetscFree(osm->y_local);
580:   }
581:   PCASMDestroySubdomains(osm->n_local_true,osm->is,osm->is_local);

583:   osm->is       = 0;
584:   osm->is_local = 0;
585:   return(0);
586: }

590: static PetscErrorCode PCDestroy_ASM(PC pc)
591: {
592:   PC_ASM         *osm = (PC_ASM*)pc->data;
594:   PetscInt       i;

597:   PCReset_ASM(pc);
598:   if (osm->ksp) {
599:     for (i=0; i<osm->n_local_true; i++) {
600:       KSPDestroy(&osm->ksp[i]);
601:     }
602:     PetscFree(osm->ksp);
603:   }
604:   PetscFree(pc->data);
605:   return(0);
606: }

610: static PetscErrorCode PCSetFromOptions_ASM(PetscOptions *PetscOptionsObject,PC pc)
611: {
612:   PC_ASM         *osm = (PC_ASM*)pc->data;
614:   PetscInt       blocks,ovl;
615:   PetscBool      symset,flg;
616:   PCASMType      asmtype;
617:   PCCompositeType loctype;

620:   /* set the type to symmetric if matrix is symmetric */
621:   if (!osm->type_set && pc->pmat) {
622:     MatIsSymmetricKnown(pc->pmat,&symset,&flg);
623:     if (symset && flg) osm->type = PC_ASM_BASIC;
624:   }
625:   PetscOptionsHead(PetscOptionsObject,"Additive Schwarz options");
626:   PetscOptionsBool("-pc_asm_dm_subdomains","Use DMCreateDomainDecomposition() to define subdomains","PCASMSetDMSubdomains",osm->dm_subdomains,&osm->dm_subdomains,&flg);
627:   PetscOptionsInt("-pc_asm_blocks","Number of subdomains","PCASMSetTotalSubdomains",osm->n,&blocks,&flg);
628:   if (flg) {
629:     PCASMSetTotalSubdomains(pc,blocks,NULL,NULL);
630:     osm->dm_subdomains = PETSC_FALSE;
631:   }
632:   PetscOptionsInt("-pc_asm_overlap","Number of grid points overlap","PCASMSetOverlap",osm->overlap,&ovl,&flg);
633:   if (flg) {
634:     PCASMSetOverlap(pc,ovl);
635:     osm->dm_subdomains = PETSC_FALSE;
636:   }
637:   flg  = PETSC_FALSE;
638:   PetscOptionsEnum("-pc_asm_type","Type of restriction/extension","PCASMSetType",PCASMTypes,(PetscEnum)osm->type,(PetscEnum*)&asmtype,&flg);
639:   if (flg) {PCASMSetType(pc,asmtype); }
640:   flg  = PETSC_FALSE;
641:   PetscOptionsEnum("-pc_asm_local_type","Type of local solver composition","PCASMSetLocalType",PCCompositeTypes,(PetscEnum)osm->loctype,(PetscEnum*)&loctype,&flg);
642:   if (flg) {PCASMSetLocalType(pc,loctype); }
643:   PetscOptionsTail();
644:   return(0);
645: }

647: /*------------------------------------------------------------------------------------*/

651: static PetscErrorCode  PCASMSetLocalSubdomains_ASM(PC pc,PetscInt n,IS is[],IS is_local[])
652: {
653:   PC_ASM         *osm = (PC_ASM*)pc->data;
655:   PetscInt       i;

658:   if (n < 1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Each process must have 1 or more blocks, n = %D",n);
659:   if (pc->setupcalled && (n != osm->n_local_true || is)) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"PCASMSetLocalSubdomains() should be called before calling PCSetUp().");

661:   if (!pc->setupcalled) {
662:     if (is) {
663:       for (i=0; i<n; i++) {PetscObjectReference((PetscObject)is[i]);}
664:     }
665:     if (is_local) {
666:       for (i=0; i<n; i++) {PetscObjectReference((PetscObject)is_local[i]);}
667:     }
668:     PCASMDestroySubdomains(osm->n_local_true,osm->is,osm->is_local);

670:     osm->n_local_true = n;
671:     osm->is           = 0;
672:     osm->is_local     = 0;
673:     if (is) {
674:       PetscMalloc1(n,&osm->is);
675:       for (i=0; i<n; i++) osm->is[i] = is[i];
676:       /* Flag indicating that the user has set overlapping subdomains so PCASM should not increase their size. */
677:       osm->overlap = -1;
678:     }
679:     if (is_local) {
680:       PetscMalloc1(n,&osm->is_local);
681:       for (i=0; i<n; i++) osm->is_local[i] = is_local[i];
682:       if (!is) {
683:         PetscMalloc1(osm->n_local_true,&osm->is);
684:         for (i=0; i<osm->n_local_true; i++) {
685:           if (osm->overlap > 0) { /* With positive overlap, osm->is[i] will be modified */
686:             ISDuplicate(osm->is_local[i],&osm->is[i]);
687:             ISCopy(osm->is_local[i],osm->is[i]);
688:           } else {
689:             PetscObjectReference((PetscObject)osm->is_local[i]);
690:             osm->is[i] = osm->is_local[i];
691:           }
692:         }
693:       }
694:     }
695:   }
696:   return(0);
697: }

701: static PetscErrorCode  PCASMSetTotalSubdomains_ASM(PC pc,PetscInt N,IS *is,IS *is_local)
702: {
703:   PC_ASM         *osm = (PC_ASM*)pc->data;
705:   PetscMPIInt    rank,size;
706:   PetscInt       n;

709:   if (N < 1) SETERRQ1(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_OUTOFRANGE,"Number of total blocks must be > 0, N = %D",N);
710:   if (is || is_local) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Use PCASMSetLocalSubdomains() to set specific index sets\n\they cannot be set globally yet.");

712:   /*
713:      Split the subdomains equally among all processors
714:   */
715:   MPI_Comm_rank(PetscObjectComm((PetscObject)pc),&rank);
716:   MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
717:   n    = N/size + ((N % size) > rank);
718:   if (!n) SETERRQ3(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Process %d must have at least one block: total processors %d total blocks %D",(int)rank,(int)size,N);
719:   if (pc->setupcalled && n != osm->n_local_true) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"PCASMSetTotalSubdomains() should be called before PCSetUp().");
720:   if (!pc->setupcalled) {
721:     PCASMDestroySubdomains(osm->n_local_true,osm->is,osm->is_local);

723:     osm->n_local_true = n;
724:     osm->is           = 0;
725:     osm->is_local     = 0;
726:   }
727:   return(0);
728: }

732: static PetscErrorCode  PCASMSetOverlap_ASM(PC pc,PetscInt ovl)
733: {
734:   PC_ASM *osm = (PC_ASM*)pc->data;

737:   if (ovl < 0) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_OUTOFRANGE,"Negative overlap value requested");
738:   if (pc->setupcalled && ovl != osm->overlap) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"PCASMSetOverlap() should be called before PCSetUp().");
739:   if (!pc->setupcalled) osm->overlap = ovl;
740:   return(0);
741: }

745: static PetscErrorCode  PCASMSetType_ASM(PC pc,PCASMType type)
746: {
747:   PC_ASM *osm = (PC_ASM*)pc->data;

750:   osm->type     = type;
751:   osm->type_set = PETSC_TRUE;
752:   return(0);
753: }

757: static PetscErrorCode  PCASMGetType_ASM(PC pc,PCASMType *type)
758: {
759:   PC_ASM *osm = (PC_ASM*)pc->data;

762:   *type = osm->type;
763:   return(0);
764: }

768: static PetscErrorCode  PCASMSetLocalType_ASM(PC pc, PCCompositeType type)
769: {
770:   PC_ASM *osm = (PC_ASM *) pc->data;

773:   osm->loctype = type;
774:   return(0);
775: }

779: static PetscErrorCode  PCASMGetLocalType_ASM(PC pc, PCCompositeType *type)
780: {
781:   PC_ASM *osm = (PC_ASM *) pc->data;

784:   *type = osm->loctype;
785:   return(0);
786: }

790: static PetscErrorCode  PCASMSetSortIndices_ASM(PC pc,PetscBool  doSort)
791: {
792:   PC_ASM *osm = (PC_ASM*)pc->data;

795:   osm->sort_indices = doSort;
796:   return(0);
797: }

801: static PetscErrorCode  PCASMGetSubKSP_ASM(PC pc,PetscInt *n_local,PetscInt *first_local,KSP **ksp)
802: {
803:   PC_ASM         *osm = (PC_ASM*)pc->data;

807:   if (osm->n_local_true < 1) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ORDER,"Need to call PCSetUP() on PC (or KSPSetUp() on the outer KSP object) before calling here");

809:   if (n_local) *n_local = osm->n_local_true;
810:   if (first_local) {
811:     MPI_Scan(&osm->n_local_true,first_local,1,MPIU_INT,MPI_SUM,PetscObjectComm((PetscObject)pc));
812:     *first_local -= osm->n_local_true;
813:   }
814:   if (ksp) {
815:     /* Assume that local solves are now different; not necessarily
816:        true though!  This flag is used only for PCView_ASM() */
817:     *ksp                   = osm->ksp;
818:     osm->same_local_solves = PETSC_FALSE;
819:   }
820:   return(0);
821: }

825: /*@C
826:     PCASMSetLocalSubdomains - Sets the local subdomains (for this processor only) for the additive Schwarz preconditioner.

828:     Collective on PC

830:     Input Parameters:
831: +   pc - the preconditioner context
832: .   n - the number of subdomains for this processor (default value = 1)
833: .   is - the index set that defines the subdomains for this processor
834:          (or NULL for PETSc to determine subdomains)
835: -   is_local - the index sets that define the local part of the subdomains for this processor
836:          (or NULL to use the default of 1 subdomain per process)

838:     Notes:
839:     The IS numbering is in the parallel, global numbering of the vector for both is and is_local

841:     By default the ASM preconditioner uses 1 block per processor.

843:     Use PCASMSetTotalSubdomains() to set the subdomains for all processors.

845:     Level: advanced

847: .keywords: PC, ASM, set, local, subdomains, additive Schwarz

849: .seealso: PCASMSetTotalSubdomains(), PCASMSetOverlap(), PCASMGetSubKSP(),
850:           PCASMCreateSubdomains2D(), PCASMGetLocalSubdomains()
851: @*/
852: PetscErrorCode  PCASMSetLocalSubdomains(PC pc,PetscInt n,IS is[],IS is_local[])
853: {

858:   PetscTryMethod(pc,"PCASMSetLocalSubdomains_C",(PC,PetscInt,IS[],IS[]),(pc,n,is,is_local));
859:   return(0);
860: }

864: /*@C
865:     PCASMSetTotalSubdomains - Sets the subdomains for all processors for the
866:     additive Schwarz preconditioner.  Either all or no processors in the
867:     PC communicator must call this routine, with the same index sets.

869:     Collective on PC

871:     Input Parameters:
872: +   pc - the preconditioner context
873: .   N  - the number of subdomains for all processors
874: .   is - the index sets that define the subdomains for all processors
875:          (or NULL to ask PETSc to compe up with subdomains)
876: -   is_local - the index sets that define the local part of the subdomains for this processor
877:          (or NULL to use the default of 1 subdomain per process)

879:     Options Database Key:
880:     To set the total number of subdomain blocks rather than specify the
881:     index sets, use the option
882: .    -pc_asm_blocks <blks> - Sets total blocks

884:     Notes:
885:     Currently you cannot use this to set the actual subdomains with the argument is.

887:     By default the ASM preconditioner uses 1 block per processor.

889:     These index sets cannot be destroyed until after completion of the
890:     linear solves for which the ASM preconditioner is being used.

892:     Use PCASMSetLocalSubdomains() to set local subdomains.

894:     The IS numbering is in the parallel, global numbering of the vector for both is and is_local

896:     Level: advanced

898: .keywords: PC, ASM, set, total, global, subdomains, additive Schwarz

900: .seealso: PCASMSetLocalSubdomains(), PCASMSetOverlap(), PCASMGetSubKSP(),
901:           PCASMCreateSubdomains2D()
902: @*/
903: PetscErrorCode  PCASMSetTotalSubdomains(PC pc,PetscInt N,IS is[],IS is_local[])
904: {

909:   PetscTryMethod(pc,"PCASMSetTotalSubdomains_C",(PC,PetscInt,IS[],IS[]),(pc,N,is,is_local));
910:   return(0);
911: }

915: /*@
916:     PCASMSetOverlap - Sets the overlap between a pair of subdomains for the
917:     additive Schwarz preconditioner.  Either all or no processors in the
918:     PC communicator must call this routine.

920:     Logically Collective on PC

922:     Input Parameters:
923: +   pc  - the preconditioner context
924: -   ovl - the amount of overlap between subdomains (ovl >= 0, default value = 1)

926:     Options Database Key:
927: .   -pc_asm_overlap <ovl> - Sets overlap

929:     Notes:
930:     By default the ASM preconditioner uses 1 block per processor.  To use
931:     multiple blocks per perocessor, see PCASMSetTotalSubdomains() and
932:     PCASMSetLocalSubdomains() (and the option -pc_asm_blocks <blks>).

934:     The overlap defaults to 1, so if one desires that no additional
935:     overlap be computed beyond what may have been set with a call to
936:     PCASMSetTotalSubdomains() or PCASMSetLocalSubdomains(), then ovl
937:     must be set to be 0.  In particular, if one does not explicitly set
938:     the subdomains an application code, then all overlap would be computed
939:     internally by PETSc, and using an overlap of 0 would result in an ASM
940:     variant that is equivalent to the block Jacobi preconditioner.

942:     Note that one can define initial index sets with any overlap via
943:     PCASMSetTotalSubdomains() or PCASMSetLocalSubdomains(); the routine
944:     PCASMSetOverlap() merely allows PETSc to extend that overlap further
945:     if desired.

947:     Level: intermediate

949: .keywords: PC, ASM, set, overlap

951: .seealso: PCASMSetTotalSubdomains(), PCASMSetLocalSubdomains(), PCASMGetSubKSP(),
952:           PCASMCreateSubdomains2D(), PCASMGetLocalSubdomains()
953: @*/
954: PetscErrorCode  PCASMSetOverlap(PC pc,PetscInt ovl)
955: {

961:   PetscTryMethod(pc,"PCASMSetOverlap_C",(PC,PetscInt),(pc,ovl));
962:   return(0);
963: }

967: /*@
968:     PCASMSetType - Sets the type of restriction and interpolation used
969:     for local problems in the additive Schwarz method.

971:     Logically Collective on PC

973:     Input Parameters:
974: +   pc  - the preconditioner context
975: -   type - variant of ASM, one of
976: .vb
977:       PC_ASM_BASIC       - full interpolation and restriction
978:       PC_ASM_RESTRICT    - full restriction, local processor interpolation
979:       PC_ASM_INTERPOLATE - full interpolation, local processor restriction
980:       PC_ASM_NONE        - local processor restriction and interpolation
981: .ve

983:     Options Database Key:
984: .   -pc_asm_type [basic,restrict,interpolate,none] - Sets ASM type

986:     Level: intermediate

988: .keywords: PC, ASM, set, type

990: .seealso: PCASMSetTotalSubdomains(), PCASMSetTotalSubdomains(), PCASMGetSubKSP(),
991:           PCASMCreateSubdomains2D()
992: @*/
993: PetscErrorCode  PCASMSetType(PC pc,PCASMType type)
994: {

1000:   PetscTryMethod(pc,"PCASMSetType_C",(PC,PCASMType),(pc,type));
1001:   return(0);
1002: }

1006: /*@
1007:     PCASMGetType - Gets the type of restriction and interpolation used
1008:     for local problems in the additive Schwarz method.

1010:     Logically Collective on PC

1012:     Input Parameter:
1013: .   pc  - the preconditioner context

1015:     Output Parameter:
1016: .   type - variant of ASM, one of

1018: .vb
1019:       PC_ASM_BASIC       - full interpolation and restriction
1020:       PC_ASM_RESTRICT    - full restriction, local processor interpolation
1021:       PC_ASM_INTERPOLATE - full interpolation, local processor restriction
1022:       PC_ASM_NONE        - local processor restriction and interpolation
1023: .ve

1025:     Options Database Key:
1026: .   -pc_asm_type [basic,restrict,interpolate,none] - Sets ASM type

1028:     Level: intermediate

1030: .keywords: PC, ASM, set, type

1032: .seealso: PCASMSetTotalSubdomains(), PCASMSetTotalSubdomains(), PCASMGetSubKSP(),
1033:           PCASMCreateSubdomains2D()
1034: @*/
1035: PetscErrorCode  PCASMGetType(PC pc,PCASMType *type)
1036: {

1041:   PetscUseMethod(pc,"PCASMGetType_C",(PC,PCASMType*),(pc,type));
1042:   return(0);
1043: }

1047: /*@
1048:   PCASMSetLocalType - Sets the type of composition used for local problems in the additive Schwarz method.

1050:   Logically Collective on PC

1052:   Input Parameters:
1053: + pc  - the preconditioner context
1054: - type - type of composition, one of
1055: .vb
1056:   PC_COMPOSITE_ADDITIVE       - local additive combination
1057:   PC_COMPOSITE_MULTIPLICATIVE - local multiplicative combination
1058: .ve

1060:   Options Database Key:
1061: . -pc_asm_local_type [additive,multiplicative] - Sets local solver composition type

1063:   Level: intermediate

1065: .seealso: PCASMSetType(), PCASMGetType(), PCASMGetLocalType(), PCASMCreate()
1066: @*/
1067: PetscErrorCode PCASMSetLocalType(PC pc, PCCompositeType type)
1068: {

1074:   PetscTryMethod(pc, "PCASMSetLocalType_C", (PC, PCCompositeType), (pc, type));
1075:   return(0);
1076: }

1080: /*@
1081:   PCASMGetLocalType - Gets the type of composition used for local problems in the additive Schwarz method.

1083:   Logically Collective on PC

1085:   Input Parameter:
1086: . pc  - the preconditioner context

1088:   Output Parameter:
1089: . type - type of composition, one of
1090: .vb
1091:   PC_COMPOSITE_ADDITIVE       - local additive combination
1092:   PC_COMPOSITE_MULTIPLICATIVE - local multiplicative combination
1093: .ve

1095:   Options Database Key:
1096: . -pc_asm_local_type [additive,multiplicative] - Sets local solver composition type

1098:   Level: intermediate

1100: .seealso: PCASMSetType(), PCASMGetType(), PCASMSetLocalType(), PCASMCreate()
1101: @*/
1102: PetscErrorCode PCASMGetLocalType(PC pc, PCCompositeType *type)
1103: {

1109:   PetscUseMethod(pc, "PCASMGetLocalType_C", (PC, PCCompositeType *), (pc, type));
1110:   return(0);
1111: }

1115: /*@
1116:     PCASMSetSortIndices - Determines whether subdomain indices are sorted.

1118:     Logically Collective on PC

1120:     Input Parameters:
1121: +   pc  - the preconditioner context
1122: -   doSort - sort the subdomain indices

1124:     Level: intermediate

1126: .keywords: PC, ASM, set, type

1128: .seealso: PCASMSetLocalSubdomains(), PCASMSetTotalSubdomains(), PCASMGetSubKSP(),
1129:           PCASMCreateSubdomains2D()
1130: @*/
1131: PetscErrorCode  PCASMSetSortIndices(PC pc,PetscBool doSort)
1132: {

1138:   PetscTryMethod(pc,"PCASMSetSortIndices_C",(PC,PetscBool),(pc,doSort));
1139:   return(0);
1140: }

1144: /*@C
1145:    PCASMGetSubKSP - Gets the local KSP contexts for all blocks on
1146:    this processor.

1148:    Collective on PC iff first_local is requested

1150:    Input Parameter:
1151: .  pc - the preconditioner context

1153:    Output Parameters:
1154: +  n_local - the number of blocks on this processor or NULL
1155: .  first_local - the global number of the first block on this processor or NULL,
1156:                  all processors must request or all must pass NULL
1157: -  ksp - the array of KSP contexts

1159:    Note:
1160:    After PCASMGetSubKSP() the array of KSPes is not to be freed.

1162:    Currently for some matrix implementations only 1 block per processor
1163:    is supported.

1165:    You must call KSPSetUp() before calling PCASMGetSubKSP().

1167:    Fortran note:
1168:    The output argument 'ksp' must be an array of sufficient length or NULL_OBJECT. The latter can be used to learn the necessary length.

1170:    Level: advanced

1172: .keywords: PC, ASM, additive Schwarz, get, sub, KSP, context

1174: .seealso: PCASMSetTotalSubdomains(), PCASMSetTotalSubdomains(), PCASMSetOverlap(),
1175:           PCASMCreateSubdomains2D(),
1176: @*/
1177: PetscErrorCode  PCASMGetSubKSP(PC pc,PetscInt *n_local,PetscInt *first_local,KSP *ksp[])
1178: {

1183:   PetscUseMethod(pc,"PCASMGetSubKSP_C",(PC,PetscInt*,PetscInt*,KSP **),(pc,n_local,first_local,ksp));
1184:   return(0);
1185: }

1187: /* -------------------------------------------------------------------------------------*/
1188: /*MC
1189:    PCASM - Use the (restricted) additive Schwarz method, each block is (approximately) solved with
1190:            its own KSP object.

1192:    Options Database Keys:
1193: +  -pc_asm_blocks <blks> - Sets total blocks
1194: .  -pc_asm_overlap <ovl> - Sets overlap
1195: -  -pc_asm_type [basic,restrict,interpolate,none] - Sets ASM type

1197:      IMPORTANT: If you run with, for example, 3 blocks on 1 processor or 3 blocks on 3 processors you
1198:       will get a different convergence rate due to the default option of -pc_asm_type restrict. Use
1199:       -pc_asm_type basic to use the standard ASM.

1201:    Notes: Each processor can have one or more blocks, but a block cannot be shared by more
1202:      than one processor. Defaults to one block per processor.

1204:      To set options on the solvers for each block append -sub_ to all the KSP, and PC
1205:         options database keys. For example, -sub_pc_type ilu -sub_pc_factor_levels 1 -sub_ksp_type preonly

1207:      To set the options on the solvers separate for each block call PCASMGetSubKSP()
1208:          and set the options directly on the resulting KSP object (you can access its PC
1209:          with KSPGetPC())


1212:    Level: beginner

1214:    Concepts: additive Schwarz method

1216:     References:
1217:     An additive variant of the Schwarz alternating method for the case of many subregions
1218:     M Dryja, OB Widlund - Courant Institute, New York University Technical report

1220:     Domain Decompositions: Parallel Multilevel Methods for Elliptic Partial Differential Equations,
1221:     Barry Smith, Petter Bjorstad, and William Gropp, Cambridge University Press, ISBN 0-521-49589-X.

1223: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC,
1224:            PCBJACOBI, PCASMGetSubKSP(), PCASMSetLocalSubdomains(),
1225:            PCASMSetTotalSubdomains(), PCSetModifySubmatrices(), PCASMSetOverlap(), PCASMSetType()

1227: M*/

1231: PETSC_EXTERN PetscErrorCode PCCreate_ASM(PC pc)
1232: {
1234:   PC_ASM         *osm;

1237:   PetscNewLog(pc,&osm);

1239:   osm->n                 = PETSC_DECIDE;
1240:   osm->n_local           = 0;
1241:   osm->n_local_true      = PETSC_DECIDE;
1242:   osm->overlap           = 1;
1243:   osm->ksp               = 0;
1244:   osm->restriction       = 0;
1245:   osm->localization      = 0;
1246:   osm->prolongation      = 0;
1247:   osm->x                 = 0;
1248:   osm->y                 = 0;
1249:   osm->y_local           = 0;
1250:   osm->is                = 0;
1251:   osm->is_local          = 0;
1252:   osm->mat               = 0;
1253:   osm->pmat              = 0;
1254:   osm->type              = PC_ASM_RESTRICT;
1255:   osm->loctype           = PC_COMPOSITE_ADDITIVE;
1256:   osm->same_local_solves = PETSC_TRUE;
1257:   osm->sort_indices      = PETSC_TRUE;
1258:   osm->dm_subdomains     = PETSC_FALSE;

1260:   pc->data                 = (void*)osm;
1261:   pc->ops->apply           = PCApply_ASM;
1262:   pc->ops->applytranspose  = PCApplyTranspose_ASM;
1263:   pc->ops->setup           = PCSetUp_ASM;
1264:   pc->ops->reset           = PCReset_ASM;
1265:   pc->ops->destroy         = PCDestroy_ASM;
1266:   pc->ops->setfromoptions  = PCSetFromOptions_ASM;
1267:   pc->ops->setuponblocks   = PCSetUpOnBlocks_ASM;
1268:   pc->ops->view            = PCView_ASM;
1269:   pc->ops->applyrichardson = 0;

1271:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetLocalSubdomains_C",PCASMSetLocalSubdomains_ASM);
1272:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetTotalSubdomains_C",PCASMSetTotalSubdomains_ASM);
1273:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetOverlap_C",PCASMSetOverlap_ASM);
1274:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetType_C",PCASMSetType_ASM);
1275:   PetscObjectComposeFunction((PetscObject)pc,"PCASMGetType_C",PCASMGetType_ASM);
1276:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetLocalType_C",PCASMSetLocalType_ASM);
1277:   PetscObjectComposeFunction((PetscObject)pc,"PCASMGetLocalType_C",PCASMGetLocalType_ASM);
1278:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetSortIndices_C",PCASMSetSortIndices_ASM);
1279:   PetscObjectComposeFunction((PetscObject)pc,"PCASMGetSubKSP_C",PCASMGetSubKSP_ASM);
1280:   return(0);
1281: }

1285: /*@C
1286:    PCASMCreateSubdomains - Creates the index sets for the overlapping Schwarz
1287:    preconditioner for a any problem on a general grid.

1289:    Collective

1291:    Input Parameters:
1292: +  A - The global matrix operator
1293: -  n - the number of local blocks

1295:    Output Parameters:
1296: .  outis - the array of index sets defining the subdomains

1298:    Level: advanced

1300:    Note: this generates nonoverlapping subdomains; the PCASM will generate the overlap
1301:     from these if you use PCASMSetLocalSubdomains()

1303:     In the Fortran version you must provide the array outis[] already allocated of length n.

1305: .keywords: PC, ASM, additive Schwarz, create, subdomains, unstructured grid

1307: .seealso: PCASMSetLocalSubdomains(), PCASMDestroySubdomains()
1308: @*/
1309: PetscErrorCode  PCASMCreateSubdomains(Mat A, PetscInt n, IS* outis[])
1310: {
1311:   MatPartitioning mpart;
1312:   const char      *prefix;
1313:   PetscErrorCode  (*f)(Mat,Mat*);
1314:   PetscMPIInt     size;
1315:   PetscInt        i,j,rstart,rend,bs;
1316:   PetscBool       isbaij = PETSC_FALSE,foundpart = PETSC_FALSE;
1317:   Mat             Ad     = NULL, adj;
1318:   IS              ispart,isnumb,*is;
1319:   PetscErrorCode  ierr;

1324:   if (n < 1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"number of local blocks must be > 0, n = %D",n);

1326:   /* Get prefix, row distribution, and block size */
1327:   MatGetOptionsPrefix(A,&prefix);
1328:   MatGetOwnershipRange(A,&rstart,&rend);
1329:   MatGetBlockSize(A,&bs);
1330:   if (rstart/bs*bs != rstart || rend/bs*bs != rend) SETERRQ3(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"bad row distribution [%D,%D) for matrix block size %D",rstart,rend,bs);

1332:   /* Get diagonal block from matrix if possible */
1333:   MPI_Comm_size(PetscObjectComm((PetscObject)A),&size);
1334:   PetscObjectQueryFunction((PetscObject)A,"MatGetDiagonalBlock_C",&f);
1335:   if (f) {
1336:     MatGetDiagonalBlock(A,&Ad);
1337:   } else if (size == 1) {
1338:     Ad = A;
1339:   }
1340:   if (Ad) {
1341:     PetscObjectTypeCompare((PetscObject)Ad,MATSEQBAIJ,&isbaij);
1342:     if (!isbaij) {PetscObjectTypeCompare((PetscObject)Ad,MATSEQSBAIJ,&isbaij);}
1343:   }
1344:   if (Ad && n > 1) {
1345:     PetscBool match,done;
1346:     /* Try to setup a good matrix partitioning if available */
1347:     MatPartitioningCreate(PETSC_COMM_SELF,&mpart);
1348:     PetscObjectSetOptionsPrefix((PetscObject)mpart,prefix);
1349:     MatPartitioningSetFromOptions(mpart);
1350:     PetscObjectTypeCompare((PetscObject)mpart,MATPARTITIONINGCURRENT,&match);
1351:     if (!match) {
1352:       PetscObjectTypeCompare((PetscObject)mpart,MATPARTITIONINGSQUARE,&match);
1353:     }
1354:     if (!match) { /* assume a "good" partitioner is available */
1355:       PetscInt       na;
1356:       const PetscInt *ia,*ja;
1357:       MatGetRowIJ(Ad,0,PETSC_TRUE,isbaij,&na,&ia,&ja,&done);
1358:       if (done) {
1359:         /* Build adjacency matrix by hand. Unfortunately a call to
1360:            MatConvert(Ad,MATMPIADJ,MAT_INITIAL_MATRIX,&adj) will
1361:            remove the block-aij structure and we cannot expect
1362:            MatPartitioning to split vertices as we need */
1363:         PetscInt       i,j,len,nnz,cnt,*iia=0,*jja=0;
1364:         const PetscInt *row;
1365:         nnz = 0;
1366:         for (i=0; i<na; i++) { /* count number of nonzeros */
1367:           len = ia[i+1] - ia[i];
1368:           row = ja + ia[i];
1369:           for (j=0; j<len; j++) {
1370:             if (row[j] == i) { /* don't count diagonal */
1371:               len--; break;
1372:             }
1373:           }
1374:           nnz += len;
1375:         }
1376:         PetscMalloc1(na+1,&iia);
1377:         PetscMalloc1(nnz,&jja);
1378:         nnz    = 0;
1379:         iia[0] = 0;
1380:         for (i=0; i<na; i++) { /* fill adjacency */
1381:           cnt = 0;
1382:           len = ia[i+1] - ia[i];
1383:           row = ja + ia[i];
1384:           for (j=0; j<len; j++) {
1385:             if (row[j] != i) { /* if not diagonal */
1386:               jja[nnz+cnt++] = row[j];
1387:             }
1388:           }
1389:           nnz     += cnt;
1390:           iia[i+1] = nnz;
1391:         }
1392:         /* Partitioning of the adjacency matrix */
1393:         MatCreateMPIAdj(PETSC_COMM_SELF,na,na,iia,jja,NULL,&adj);
1394:         MatPartitioningSetAdjacency(mpart,adj);
1395:         MatPartitioningSetNParts(mpart,n);
1396:         MatPartitioningApply(mpart,&ispart);
1397:         ISPartitioningToNumbering(ispart,&isnumb);
1398:         MatDestroy(&adj);
1399:         foundpart = PETSC_TRUE;
1400:       }
1401:       MatRestoreRowIJ(Ad,0,PETSC_TRUE,isbaij,&na,&ia,&ja,&done);
1402:     }
1403:     MatPartitioningDestroy(&mpart);
1404:   }

1406:   PetscMalloc1(n,&is);
1407:   *outis = is;

1409:   if (!foundpart) {

1411:     /* Partitioning by contiguous chunks of rows */

1413:     PetscInt mbs   = (rend-rstart)/bs;
1414:     PetscInt start = rstart;
1415:     for (i=0; i<n; i++) {
1416:       PetscInt count = (mbs/n + ((mbs % n) > i)) * bs;
1417:       ISCreateStride(PETSC_COMM_SELF,count,start,1,&is[i]);
1418:       start += count;
1419:     }

1421:   } else {

1423:     /* Partitioning by adjacency of diagonal block  */

1425:     const PetscInt *numbering;
1426:     PetscInt       *count,nidx,*indices,*newidx,start=0;
1427:     /* Get node count in each partition */
1428:     PetscMalloc1(n,&count);
1429:     ISPartitioningCount(ispart,n,count);
1430:     if (isbaij && bs > 1) { /* adjust for the block-aij case */
1431:       for (i=0; i<n; i++) count[i] *= bs;
1432:     }
1433:     /* Build indices from node numbering */
1434:     ISGetLocalSize(isnumb,&nidx);
1435:     PetscMalloc1(nidx,&indices);
1436:     for (i=0; i<nidx; i++) indices[i] = i; /* needs to be initialized */
1437:     ISGetIndices(isnumb,&numbering);
1438:     PetscSortIntWithPermutation(nidx,numbering,indices);
1439:     ISRestoreIndices(isnumb,&numbering);
1440:     if (isbaij && bs > 1) { /* adjust for the block-aij case */
1441:       PetscMalloc1(nidx*bs,&newidx);
1442:       for (i=0; i<nidx; i++) {
1443:         for (j=0; j<bs; j++) newidx[i*bs+j] = indices[i]*bs + j;
1444:       }
1445:       PetscFree(indices);
1446:       nidx   *= bs;
1447:       indices = newidx;
1448:     }
1449:     /* Shift to get global indices */
1450:     for (i=0; i<nidx; i++) indices[i] += rstart;

1452:     /* Build the index sets for each block */
1453:     for (i=0; i<n; i++) {
1454:       ISCreateGeneral(PETSC_COMM_SELF,count[i],&indices[start],PETSC_COPY_VALUES,&is[i]);
1455:       ISSort(is[i]);
1456:       start += count[i];
1457:     }

1459:     PetscFree(count);
1460:     PetscFree(indices);
1461:     ISDestroy(&isnumb);
1462:     ISDestroy(&ispart);

1464:   }
1465:   return(0);
1466: }

1470: /*@C
1471:    PCASMDestroySubdomains - Destroys the index sets created with
1472:    PCASMCreateSubdomains(). Should be called after setting subdomains
1473:    with PCASMSetLocalSubdomains().

1475:    Collective

1477:    Input Parameters:
1478: +  n - the number of index sets
1479: .  is - the array of index sets
1480: -  is_local - the array of local index sets, can be NULL

1482:    Level: advanced

1484: .keywords: PC, ASM, additive Schwarz, create, subdomains, unstructured grid

1486: .seealso: PCASMCreateSubdomains(), PCASMSetLocalSubdomains()
1487: @*/
1488: PetscErrorCode  PCASMDestroySubdomains(PetscInt n, IS is[], IS is_local[])
1489: {
1490:   PetscInt       i;

1494:   if (n <= 0) return(0);
1495:   if (is) {
1497:     for (i=0; i<n; i++) { ISDestroy(&is[i]); }
1498:     PetscFree(is);
1499:   }
1500:   if (is_local) {
1502:     for (i=0; i<n; i++) { ISDestroy(&is_local[i]); }
1503:     PetscFree(is_local);
1504:   }
1505:   return(0);
1506: }

1510: /*@
1511:    PCASMCreateSubdomains2D - Creates the index sets for the overlapping Schwarz
1512:    preconditioner for a two-dimensional problem on a regular grid.

1514:    Not Collective

1516:    Input Parameters:
1517: +  m, n - the number of mesh points in the x and y directions
1518: .  M, N - the number of subdomains in the x and y directions
1519: .  dof - degrees of freedom per node
1520: -  overlap - overlap in mesh lines

1522:    Output Parameters:
1523: +  Nsub - the number of subdomains created
1524: .  is - array of index sets defining overlapping (if overlap > 0) subdomains
1525: -  is_local - array of index sets defining non-overlapping subdomains

1527:    Note:
1528:    Presently PCAMSCreateSubdomains2d() is valid only for sequential
1529:    preconditioners.  More general related routines are
1530:    PCASMSetTotalSubdomains() and PCASMSetLocalSubdomains().

1532:    Level: advanced

1534: .keywords: PC, ASM, additive Schwarz, create, subdomains, 2D, regular grid

1536: .seealso: PCASMSetTotalSubdomains(), PCASMSetLocalSubdomains(), PCASMGetSubKSP(),
1537:           PCASMSetOverlap()
1538: @*/
1539: PetscErrorCode  PCASMCreateSubdomains2D(PetscInt m,PetscInt n,PetscInt M,PetscInt N,PetscInt dof,PetscInt overlap,PetscInt *Nsub,IS **is,IS **is_local)
1540: {
1541:   PetscInt       i,j,height,width,ystart,xstart,yleft,yright,xleft,xright,loc_outer;
1543:   PetscInt       nidx,*idx,loc,ii,jj,count;

1546:   if (dof != 1) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP," ");

1548:   *Nsub     = N*M;
1549:   PetscMalloc1(*Nsub,is);
1550:   PetscMalloc1(*Nsub,is_local);
1551:   ystart    = 0;
1552:   loc_outer = 0;
1553:   for (i=0; i<N; i++) {
1554:     height = n/N + ((n % N) > i); /* height of subdomain */
1555:     if (height < 2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many N subdomains for mesh dimension n");
1556:     yleft  = ystart - overlap; if (yleft < 0) yleft = 0;
1557:     yright = ystart + height + overlap; if (yright > n) yright = n;
1558:     xstart = 0;
1559:     for (j=0; j<M; j++) {
1560:       width = m/M + ((m % M) > j); /* width of subdomain */
1561:       if (width < 2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many M subdomains for mesh dimension m");
1562:       xleft  = xstart - overlap; if (xleft < 0) xleft = 0;
1563:       xright = xstart + width + overlap; if (xright > m) xright = m;
1564:       nidx   = (xright - xleft)*(yright - yleft);
1565:       PetscMalloc1(nidx,&idx);
1566:       loc    = 0;
1567:       for (ii=yleft; ii<yright; ii++) {
1568:         count = m*ii + xleft;
1569:         for (jj=xleft; jj<xright; jj++) idx[loc++] = count++;
1570:       }
1571:       ISCreateGeneral(PETSC_COMM_SELF,nidx,idx,PETSC_COPY_VALUES,(*is)+loc_outer);
1572:       if (overlap == 0) {
1573:         PetscObjectReference((PetscObject)(*is)[loc_outer]);

1575:         (*is_local)[loc_outer] = (*is)[loc_outer];
1576:       } else {
1577:         for (loc=0,ii=ystart; ii<ystart+height; ii++) {
1578:           for (jj=xstart; jj<xstart+width; jj++) {
1579:             idx[loc++] = m*ii + jj;
1580:           }
1581:         }
1582:         ISCreateGeneral(PETSC_COMM_SELF,loc,idx,PETSC_COPY_VALUES,*is_local+loc_outer);
1583:       }
1584:       PetscFree(idx);
1585:       xstart += width;
1586:       loc_outer++;
1587:     }
1588:     ystart += height;
1589:   }
1590:   for (i=0; i<*Nsub; i++) { ISSort((*is)[i]); }
1591:   return(0);
1592: }

1596: /*@C
1597:     PCASMGetLocalSubdomains - Gets the local subdomains (for this processor
1598:     only) for the additive Schwarz preconditioner.

1600:     Not Collective

1602:     Input Parameter:
1603: .   pc - the preconditioner context

1605:     Output Parameters:
1606: +   n - the number of subdomains for this processor (default value = 1)
1607: .   is - the index sets that define the subdomains for this processor
1608: -   is_local - the index sets that define the local part of the subdomains for this processor (can be NULL)


1611:     Notes:
1612:     The IS numbering is in the parallel, global numbering of the vector.

1614:     Level: advanced

1616: .keywords: PC, ASM, set, local, subdomains, additive Schwarz

1618: .seealso: PCASMSetTotalSubdomains(), PCASMSetOverlap(), PCASMGetSubKSP(),
1619:           PCASMCreateSubdomains2D(), PCASMSetLocalSubdomains(), PCASMGetLocalSubmatrices()
1620: @*/
1621: PetscErrorCode  PCASMGetLocalSubdomains(PC pc,PetscInt *n,IS *is[],IS *is_local[])
1622: {
1623:   PC_ASM         *osm;
1625:   PetscBool      match;

1631:   PetscObjectTypeCompare((PetscObject)pc,PCASM,&match);
1632:   if (!match) {
1633:     if (n) *n = 0;
1634:     if (is) *is = NULL;
1635:   } else {
1636:     osm = (PC_ASM*)pc->data;
1637:     if (n) *n = osm->n_local_true;
1638:     if (is) *is = osm->is;
1639:     if (is_local) *is_local = osm->is_local;
1640:   }
1641:   return(0);
1642: }

1646: /*@C
1647:     PCASMGetLocalSubmatrices - Gets the local submatrices (for this processor
1648:     only) for the additive Schwarz preconditioner.

1650:     Not Collective

1652:     Input Parameter:
1653: .   pc - the preconditioner context

1655:     Output Parameters:
1656: +   n - the number of matrices for this processor (default value = 1)
1657: -   mat - the matrices


1660:     Level: advanced

1662:     Notes: Call after PCSetUp() (or KSPSetUp()) but before PCApply() (or KSPApply()) and before PCSetUpOnBlocks())

1664:            Usually one would use PCSetModifySubmatrices() to change the submatrices in building the preconditioner.

1666: .keywords: PC, ASM, set, local, subdomains, additive Schwarz, block Jacobi

1668: .seealso: PCASMSetTotalSubdomains(), PCASMSetOverlap(), PCASMGetSubKSP(),
1669:           PCASMCreateSubdomains2D(), PCASMSetLocalSubdomains(), PCASMGetLocalSubdomains(), PCSetModifySubmatrices()
1670: @*/
1671: PetscErrorCode  PCASMGetLocalSubmatrices(PC pc,PetscInt *n,Mat *mat[])
1672: {
1673:   PC_ASM         *osm;
1675:   PetscBool      match;

1681:   if (!pc->setupcalled) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Must call after KSPSetUP() or PCSetUp().");
1682:   PetscObjectTypeCompare((PetscObject)pc,PCASM,&match);
1683:   if (!match) {
1684:     if (n) *n = 0;
1685:     if (mat) *mat = NULL;
1686:   } else {
1687:     osm = (PC_ASM*)pc->data;
1688:     if (n) *n = osm->n_local_true;
1689:     if (mat) *mat = osm->pmat;
1690:   }
1691:   return(0);
1692: }

1696: /*@
1697:     PCASMSetDMSubdomains - Indicates whether to use DMCreateDomainDecomposition() to define the subdomains, whenever possible.
1698:     Logically Collective

1700:     Input Parameter:
1701: +   pc  - the preconditioner
1702: -   flg - boolean indicating whether to use subdomains defined by the DM

1704:     Options Database Key:
1705: .   -pc_asm_dm_subdomains

1707:     Level: intermediate

1709:     Notes:
1710:     PCASMSetTotalSubdomains() and PCASMSetOverlap() take precedence over PCASMSetDMSubdomains(),
1711:     so setting either of the first two effectively turns the latter off.

1713: .keywords: PC, ASM, DM, set, subdomains, additive Schwarz

1715: .seealso: PCASMGetDMSubdomains(), PCASMSetTotalSubdomains(), PCASMSetOverlap()
1716:           PCASMCreateSubdomains2D(), PCASMSetLocalSubdomains(), PCASMGetLocalSubdomains()
1717: @*/
1718: PetscErrorCode  PCASMSetDMSubdomains(PC pc,PetscBool flg)
1719: {
1720:   PC_ASM         *osm = (PC_ASM*)pc->data;
1722:   PetscBool      match;

1727:   if (pc->setupcalled) SETERRQ(((PetscObject)pc)->comm,PETSC_ERR_ARG_WRONGSTATE,"Not for a setup PC.");
1728:   PetscObjectTypeCompare((PetscObject)pc,PCASM,&match);
1729:   if (match) {
1730:     osm->dm_subdomains = flg;
1731:   }
1732:   return(0);
1733: }

1737: /*@
1738:     PCASMGetDMSubdomains - Returns flag indicating whether to use DMCreateDomainDecomposition() to define the subdomains, whenever possible.
1739:     Not Collective

1741:     Input Parameter:
1742: .   pc  - the preconditioner

1744:     Output Parameter:
1745: .   flg - boolean indicating whether to use subdomains defined by the DM

1747:     Level: intermediate

1749: .keywords: PC, ASM, DM, set, subdomains, additive Schwarz

1751: .seealso: PCASMSetDMSubdomains(), PCASMSetTotalSubdomains(), PCASMSetOverlap()
1752:           PCASMCreateSubdomains2D(), PCASMSetLocalSubdomains(), PCASMGetLocalSubdomains()
1753: @*/
1754: PetscErrorCode  PCASMGetDMSubdomains(PC pc,PetscBool* flg)
1755: {
1756:   PC_ASM         *osm = (PC_ASM*)pc->data;
1758:   PetscBool      match;

1763:   PetscObjectTypeCompare((PetscObject)pc,PCASM,&match);
1764:   if (match) {
1765:     if (flg) *flg = osm->dm_subdomains;
1766:   }
1767:   return(0);
1768: }