Actual source code: gasm.c

  1: /*
  2:   This file defines an "generalized" additive Schwarz preconditioner for any Mat implementation.
  3:   In this version each processor may intersect multiple subdomains and any subdomain may
  4:   intersect multiple processors.  Intersections of subdomains with processors are called *local
  5:   subdomains*.

  7:        N    - total number of distinct global subdomains          (set explicitly in PCGASMSetTotalSubdomains() or implicitly PCGASMSetSubdomains() and then calculated in PCSetUp_GASM())
  8:        n    - actual number of local subdomains on this processor (set in PCGASMSetSubdomains() or calculated in PCGASMSetTotalSubdomains())
  9:        nmax - maximum number of local subdomains per processor    (calculated in PCSetUp_GASM())
 10: */
 11: #include <petsc/private/pcimpl.h>
 12: #include <petscdm.h>

 14: typedef struct {
 15:   PetscInt    N,n,nmax;
 16:   PetscInt    overlap;                  /* overlap requested by user */
 17:   PCGASMType  type;                     /* use reduced interpolation, restriction or both */
 18:   PetscBool   type_set;                 /* if user set this value (so won't change it for symmetric problems) */
 19:   PetscBool   same_subdomain_solvers;   /* flag indicating whether all local solvers are same */
 20:   PetscBool   sort_indices;             /* flag to sort subdomain indices */
 21:   PetscBool   user_subdomains;          /* whether the user set explicit subdomain index sets -- keep them on PCReset() */
 22:   PetscBool   dm_subdomains;            /* whether DM is allowed to define subdomains */
 23:   PetscBool   hierarchicalpartitioning;
 24:   IS          *ois;                     /* index sets that define the outer (conceptually, overlapping) subdomains */
 25:   IS          *iis;                     /* index sets that define the inner (conceptually, nonoverlapping) subdomains */
 26:   KSP         *ksp;                     /* linear solvers for each subdomain */
 27:   Mat         *pmat;                    /* subdomain block matrices */
 28:   Vec         gx,gy;                    /* Merged work vectors */
 29:   Vec         *x,*y;                    /* Split work vectors; storage aliases pieces of storage of the above merged vectors. */
 30:   VecScatter  gorestriction;            /* merged restriction to disjoint union of outer subdomains */
 31:   VecScatter  girestriction;            /* merged restriction to disjoint union of inner subdomains */
 32:   VecScatter  pctoouter;
 33:   IS          permutationIS;
 34:   Mat         permutationP;
 35:   Mat         pcmat;
 36:   Vec         pcx,pcy;
 37: } PC_GASM;

 39: static PetscErrorCode  PCGASMComputeGlobalSubdomainNumbering_Private(PC pc,PetscInt **numbering,PetscInt **permutation)
 40: {
 41:   PC_GASM        *osm = (PC_GASM*)pc->data;
 42:   PetscInt       i;

 46:   /* Determine the number of globally-distinct subdomains and compute a global numbering for them. */
 47:   PetscMalloc2(osm->n,numbering,osm->n,permutation);
 48:   PetscObjectsListGetGlobalNumbering(PetscObjectComm((PetscObject)pc),osm->n,(PetscObject*)osm->iis,NULL,*numbering);
 49:   for (i = 0; i < osm->n; ++i) (*permutation)[i] = i;
 50:   PetscSortIntWithPermutation(osm->n,*numbering,*permutation);
 51:   return(0);
 52: }

 54: static PetscErrorCode  PCGASMSubdomainView_Private(PC pc, PetscInt i, PetscViewer viewer)
 55: {
 56:   PC_GASM        *osm = (PC_GASM*)pc->data;
 57:   PetscInt       j,nidx;
 58:   const PetscInt *idx;
 59:   PetscViewer    sviewer;
 60:   char           *cidx;

 64:   if (i < 0 || i > osm->n) SETERRQ2(PetscObjectComm((PetscObject)viewer), PETSC_ERR_ARG_WRONG, "Invalid subdomain %D: must nonnegative and less than %D", i, osm->n);
 65:   /* Inner subdomains. */
 66:   ISGetLocalSize(osm->iis[i], &nidx);
 67:   /*
 68:    No more than 15 characters per index plus a space.
 69:    PetscViewerStringSPrintf requires a string of size at least 2, so use (nidx+1) instead of nidx,
 70:    in case nidx == 0. That will take care of the space for the trailing '\0' as well.
 71:    For nidx == 0, the whole string 16 '\0'.
 72:    */
 73: #define len  16*(nidx+1)+1
 74:   PetscMalloc1(len, &cidx);
 75:   PetscViewerStringOpen(PETSC_COMM_SELF, cidx, len, &sviewer);
 76: #undef len
 77:   ISGetIndices(osm->iis[i], &idx);
 78:   for (j = 0; j < nidx; ++j) {
 79:     PetscViewerStringSPrintf(sviewer, "%D ", idx[j]);
 80:   }
 81:   ISRestoreIndices(osm->iis[i],&idx);
 82:   PetscViewerDestroy(&sviewer);
 83:   PetscViewerASCIIPrintf(viewer, "Inner subdomain:\n");
 84:   PetscViewerFlush(viewer);
 85:   PetscViewerASCIIPushSynchronized(viewer);
 86:   PetscViewerASCIISynchronizedPrintf(viewer, "%s", cidx);
 87:   PetscViewerFlush(viewer);
 88:   PetscViewerASCIIPopSynchronized(viewer);
 89:   PetscViewerASCIIPrintf(viewer, "\n");
 90:   PetscViewerFlush(viewer);
 91:   PetscFree(cidx);
 92:   /* Outer subdomains. */
 93:   ISGetLocalSize(osm->ois[i], &nidx);
 94:   /*
 95:    No more than 15 characters per index plus a space.
 96:    PetscViewerStringSPrintf requires a string of size at least 2, so use (nidx+1) instead of nidx,
 97:    in case nidx == 0. That will take care of the space for the trailing '\0' as well.
 98:    For nidx == 0, the whole string 16 '\0'.
 99:    */
100: #define len  16*(nidx+1)+1
101:   PetscMalloc1(len, &cidx);
102:   PetscViewerStringOpen(PETSC_COMM_SELF, cidx, len, &sviewer);
103: #undef len
104:   ISGetIndices(osm->ois[i], &idx);
105:   for (j = 0; j < nidx; ++j) {
106:     PetscViewerStringSPrintf(sviewer,"%D ", idx[j]);
107:   }
108:   PetscViewerDestroy(&sviewer);
109:   ISRestoreIndices(osm->ois[i],&idx);
110:   PetscViewerASCIIPrintf(viewer, "Outer subdomain:\n");
111:   PetscViewerFlush(viewer);
112:   PetscViewerASCIIPushSynchronized(viewer);
113:   PetscViewerASCIISynchronizedPrintf(viewer, "%s", cidx);
114:   PetscViewerFlush(viewer);
115:   PetscViewerASCIIPopSynchronized(viewer);
116:   PetscViewerASCIIPrintf(viewer, "\n");
117:   PetscViewerFlush(viewer);
118:   PetscFree(cidx);
119:   return(0);
120: }

122: static PetscErrorCode  PCGASMPrintSubdomains(PC pc)
123: {
124:   PC_GASM        *osm = (PC_GASM*)pc->data;
125:   const char     *prefix;
126:   char           fname[PETSC_MAX_PATH_LEN+1];
127:   PetscInt       l, d, count;
128:   PetscBool      doprint,found;
129:   PetscViewer    viewer, sviewer = NULL;
130:   PetscInt       *numbering,*permutation;/* global numbering of locally-supported subdomains and the permutation from the local ordering */

134:   PCGetOptionsPrefix(pc,&prefix);
135:   doprint  = PETSC_FALSE;
136:   PetscOptionsGetBool(NULL,prefix,"-pc_gasm_print_subdomains",&doprint,NULL);
137:   if (!doprint) return(0);
138:   PetscOptionsGetString(NULL,prefix,"-pc_gasm_print_subdomains",fname,sizeof(fname),&found);
139:   if (!found) { PetscStrcpy(fname,"stdout"); };
140:   PetscViewerASCIIOpen(PetscObjectComm((PetscObject)pc),fname,&viewer);
141:   /*
142:    Make sure the viewer has a name. Otherwise this may cause a deadlock or other weird errors when creating a subcomm viewer:
143:    the subcomm viewer will attempt to inherit the viewer's name, which, if not set, will be constructed collectively on the comm.
144:   */
145:   PetscObjectName((PetscObject)viewer);
146:   l    = 0;
147:   PCGASMComputeGlobalSubdomainNumbering_Private(pc,&numbering,&permutation);
148:   for (count = 0; count < osm->N; ++count) {
149:     /* Now let subdomains go one at a time in the global numbering order and print their subdomain/solver info. */
150:     if (l<osm->n) {
151:       d = permutation[l]; /* d is the local number of the l-th smallest (in the global ordering) among the locally supported subdomains */
152:       if (numbering[d] == count) {
153:         PetscViewerGetSubViewer(viewer,((PetscObject)osm->ois[d])->comm, &sviewer);
154:         PCGASMSubdomainView_Private(pc,d,sviewer);
155:         PetscViewerRestoreSubViewer(viewer,((PetscObject)osm->ois[d])->comm, &sviewer);
156:         ++l;
157:       }
158:     }
159:     MPI_Barrier(PetscObjectComm((PetscObject)pc));
160:   }
161:   PetscFree2(numbering,permutation);
162:   PetscViewerDestroy(&viewer);
163:   return(0);
164: }

166: static PetscErrorCode PCView_GASM(PC pc,PetscViewer viewer)
167: {
168:   PC_GASM        *osm = (PC_GASM*)pc->data;
169:   const char     *prefix;
171:   PetscMPIInt    rank, size;
172:   PetscInt       bsz;
173:   PetscBool      iascii,view_subdomains=PETSC_FALSE;
174:   PetscViewer    sviewer;
175:   PetscInt       count, l;
176:   char           overlap[256]     = "user-defined overlap";
177:   char           gsubdomains[256] = "unknown total number of subdomains";
178:   char           msubdomains[256] = "unknown max number of local subdomains";
179:   PetscInt       *numbering,*permutation;/* global numbering of locally-supported subdomains and the permutation from the local ordering */

182:   MPI_Comm_size(PetscObjectComm((PetscObject)pc), &size);
183:   MPI_Comm_rank(PetscObjectComm((PetscObject)pc), &rank);

185:   if (osm->overlap >= 0) {
186:     PetscSNPrintf(overlap,sizeof(overlap),"requested amount of overlap = %D",osm->overlap);
187:   }
188:   if (osm->N != PETSC_DETERMINE) {
189:     PetscSNPrintf(gsubdomains, sizeof(gsubdomains), "total number of subdomains = %D",osm->N);
190:   }
191:   if (osm->nmax != PETSC_DETERMINE) {
192:     PetscSNPrintf(msubdomains,sizeof(msubdomains),"max number of local subdomains = %D",osm->nmax);
193:   }

195:   PCGetOptionsPrefix(pc,&prefix);
196:   PetscOptionsGetBool(NULL,prefix,"-pc_gasm_view_subdomains",&view_subdomains,NULL);

198:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
199:   if (iascii) {
200:     /*
201:      Make sure the viewer has a name. Otherwise this may cause a deadlock when creating a subcomm viewer:
202:      the subcomm viewer will attempt to inherit the viewer's name, which, if not set, will be constructed
203:      collectively on the comm.
204:      */
205:     PetscObjectName((PetscObject)viewer);
206:     PetscViewerASCIIPrintf(viewer,"  Restriction/interpolation type: %s\n",PCGASMTypes[osm->type]);
207:     PetscViewerASCIIPrintf(viewer,"  %s\n",overlap);
208:     PetscViewerASCIIPrintf(viewer,"  %s\n",gsubdomains);
209:     PetscViewerASCIIPrintf(viewer,"  %s\n",msubdomains);
210:     PetscViewerASCIIPushSynchronized(viewer);
211:     PetscViewerASCIISynchronizedPrintf(viewer,"  [%d|%d] number of locally-supported subdomains = %D\n",rank,size,osm->n);
212:     PetscViewerFlush(viewer);
213:     PetscViewerASCIIPopSynchronized(viewer);
214:     /* Cannot take advantage of osm->same_subdomain_solvers without a global numbering of subdomains. */
215:     PetscViewerASCIIPrintf(viewer,"  Subdomain solver info is as follows:\n");
216:     PetscViewerASCIIPushTab(viewer);
217:     PetscViewerASCIIPrintf(viewer,"  - - - - - - - - - - - - - - - - - -\n");
218:     /* Make sure that everybody waits for the banner to be printed. */
219:     MPI_Barrier(PetscObjectComm((PetscObject)viewer));
220:     /* Now let subdomains go one at a time in the global numbering order and print their subdomain/solver info. */
221:     PCGASMComputeGlobalSubdomainNumbering_Private(pc,&numbering,&permutation);
222:     l = 0;
223:     for (count = 0; count < osm->N; ++count) {
224:       PetscMPIInt srank, ssize;
225:       if (l<osm->n) {
226:         PetscInt d = permutation[l]; /* d is the local number of the l-th smallest (in the global ordering) among the locally supported subdomains */
227:         if (numbering[d] == count) {
228:           MPI_Comm_size(((PetscObject)osm->ois[d])->comm, &ssize);
229:           MPI_Comm_rank(((PetscObject)osm->ois[d])->comm, &srank);
230:           PetscViewerGetSubViewer(viewer,((PetscObject)osm->ois[d])->comm, &sviewer);
231:           ISGetLocalSize(osm->ois[d],&bsz);
232:           PetscViewerASCIISynchronizedPrintf(sviewer,"  [%d|%d] (subcomm [%d|%d]) local subdomain number %D, local size = %D\n",rank,size,srank,ssize,d,bsz);
233:           PetscViewerFlush(sviewer);
234:           if (view_subdomains) {
235:             PCGASMSubdomainView_Private(pc,d,sviewer);
236:           }
237:           if (!pc->setupcalled) {
238:             PetscViewerASCIIPrintf(sviewer, "  Solver not set up yet: PCSetUp() not yet called\n");
239:           } else {
240:             KSPView(osm->ksp[d],sviewer);
241:           }
242:           PetscViewerASCIIPrintf(sviewer,"  - - - - - - - - - - - - - - - - - -\n");
243:           PetscViewerFlush(sviewer);
244:           PetscViewerRestoreSubViewer(viewer,((PetscObject)osm->ois[d])->comm, &sviewer);
245:           ++l;
246:         }
247:       }
248:       MPI_Barrier(PetscObjectComm((PetscObject)pc));
249:     }
250:     PetscFree2(numbering,permutation);
251:     PetscViewerASCIIPopTab(viewer);
252:     PetscViewerFlush(viewer);
253:     /* this line is needed to match the extra PetscViewerASCIIPushSynchronized() in PetscViewerGetSubViewer() */
254:     PetscViewerASCIIPopSynchronized(viewer);
255:   }
256:   return(0);
257: }

259: PETSC_INTERN PetscErrorCode  PCGASMCreateLocalSubdomains(Mat A, PetscInt nloc, IS *iis[]);

261: PetscErrorCode PCGASMSetHierarchicalPartitioning(PC pc)
262: {
263:    PC_GASM              *osm = (PC_GASM*)pc->data;
264:    MatPartitioning       part;
265:    MPI_Comm              comm;
266:    PetscMPIInt           size;
267:    PetscInt              nlocalsubdomains,fromrows_localsize;
268:    IS                    partitioning,fromrows,isn;
269:    Vec                   outervec;
270:    PetscErrorCode        ierr;

273:    PetscObjectGetComm((PetscObject)pc,&comm);
274:    MPI_Comm_size(comm,&size);
275:    /* we do not need a hierarchical partitioning when
276:     * the total number of subdomains is consistent with
277:     * the number of MPI tasks.
278:     * For the following cases, we do not need to use HP
279:     * */
280:    if (osm->N==PETSC_DETERMINE || osm->N>=size || osm->N==1) return(0);
281:    if (size%osm->N != 0) SETERRQ2(PETSC_COMM_WORLD,PETSC_ERR_ARG_INCOMP,"have to specify the total number of subdomains %D to be a factor of the number of processors %d \n",osm->N,size);
282:    nlocalsubdomains = size/osm->N;
283:    osm->n           = 1;
284:    MatPartitioningCreate(comm,&part);
285:    MatPartitioningSetAdjacency(part,pc->pmat);
286:    MatPartitioningSetType(part,MATPARTITIONINGHIERARCH);
287:    MatPartitioningHierarchicalSetNcoarseparts(part,osm->N);
288:    MatPartitioningHierarchicalSetNfineparts(part,nlocalsubdomains);
289:    MatPartitioningSetFromOptions(part);
290:    /* get new processor owner number of each vertex */
291:    MatPartitioningApply(part,&partitioning);
292:    ISBuildTwoSided(partitioning,NULL,&fromrows);
293:    ISPartitioningToNumbering(partitioning,&isn);
294:    ISDestroy(&isn);
295:    ISGetLocalSize(fromrows,&fromrows_localsize);
296:    MatPartitioningDestroy(&part);
297:    MatCreateVecs(pc->pmat,&outervec,NULL);
298:    VecCreateMPI(comm,fromrows_localsize,PETSC_DETERMINE,&(osm->pcx));
299:    VecDuplicate(osm->pcx,&(osm->pcy));
300:    VecScatterCreate(osm->pcx,NULL,outervec,fromrows,&(osm->pctoouter));
301:    MatCreateSubMatrix(pc->pmat,fromrows,fromrows,MAT_INITIAL_MATRIX,&(osm->permutationP));
302:    PetscObjectReference((PetscObject)fromrows);
303:    osm->permutationIS = fromrows;
304:    osm->pcmat =  pc->pmat;
305:    PetscObjectReference((PetscObject)osm->permutationP);
306:    pc->pmat = osm->permutationP;
307:    VecDestroy(&outervec);
308:    ISDestroy(&fromrows);
309:    ISDestroy(&partitioning);
310:    osm->n           = PETSC_DETERMINE;
311:    return(0);
312: }

314: static PetscErrorCode PCSetUp_GASM(PC pc)
315: {
316:   PC_GASM        *osm = (PC_GASM*)pc->data;
318:   PetscInt       i,nInnerIndices,nTotalInnerIndices;
319:   PetscMPIInt    rank, size;
320:   MatReuse       scall = MAT_REUSE_MATRIX;
321:   KSP            ksp;
322:   PC             subpc;
323:   const char     *prefix,*pprefix;
324:   Vec            x,y;
325:   PetscInt       oni;       /* Number of indices in the i-th local outer subdomain.               */
326:   const PetscInt *oidxi;    /* Indices from the i-th subdomain local outer subdomain.             */
327:   PetscInt       on;        /* Number of indices in the disjoint union of local outer subdomains. */
328:   PetscInt       *oidx;     /* Indices in the disjoint union of local outer subdomains. */
329:   IS             gois;      /* Disjoint union the global indices of outer subdomains.             */
330:   IS             goid;      /* Identity IS of the size of the disjoint union of outer subdomains. */
331:   PetscScalar    *gxarray, *gyarray;
332:   PetscInt       gostart;   /* Start of locally-owned indices in the vectors -- osm->gx,osm->gy -- over the disjoint union of outer subdomains. */
333:   PetscInt       num_subdomains    = 0;
334:   DM             *subdomain_dm     = NULL;
335:   char           **subdomain_names = NULL;
336:   PetscInt       *numbering;

339:   MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
340:   MPI_Comm_rank(PetscObjectComm((PetscObject)pc),&rank);
341:   if (!pc->setupcalled) {
342:         /* use a hierarchical partitioning */
343:     if (osm->hierarchicalpartitioning) {
344:       PCGASMSetHierarchicalPartitioning(pc);
345:     }
346:     if (osm->n == PETSC_DETERMINE) {
347:       if (osm->N != PETSC_DETERMINE) {
348:            /* No local subdomains given, but the desired number of total subdomains is known, so construct them accordingly. */
349:            PCGASMCreateSubdomains(pc->pmat,osm->N,&osm->n,&osm->iis);
350:       } else if (osm->dm_subdomains && pc->dm) {
351:         /* try pc->dm next, if allowed */
352:         PetscInt  d;
353:         IS       *inner_subdomain_is, *outer_subdomain_is;
354:         DMCreateDomainDecomposition(pc->dm, &num_subdomains, &subdomain_names, &inner_subdomain_is, &outer_subdomain_is, &subdomain_dm);
355:         if (num_subdomains) {
356:           PCGASMSetSubdomains(pc, num_subdomains, inner_subdomain_is, outer_subdomain_is);
357:         }
358:         for (d = 0; d < num_subdomains; ++d) {
359:           if (inner_subdomain_is) {ISDestroy(&inner_subdomain_is[d]);}
360:           if (outer_subdomain_is) {ISDestroy(&outer_subdomain_is[d]);}
361:         }
362:         PetscFree(inner_subdomain_is);
363:         PetscFree(outer_subdomain_is);
364:       } else {
365:         /* still no subdomains; use one per processor */
366:         osm->nmax = osm->n = 1;
367:         MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
368:         osm->N    = size;
369:         PCGASMCreateLocalSubdomains(pc->pmat,osm->n,&osm->iis);
370:       }
371:     }
372:     if (!osm->iis) {
373:       /*
374:        osm->n was set in PCGASMSetSubdomains(), but the actual subdomains have not been supplied.
375:        We create the requisite number of local inner subdomains and then expand them into
376:        out subdomains, if necessary.
377:        */
378:       PCGASMCreateLocalSubdomains(pc->pmat,osm->n,&osm->iis);
379:     }
380:     if (!osm->ois) {
381:       /*
382:             Initially make outer subdomains the same as inner subdomains. If nonzero additional overlap
383:             has been requested, copy the inner subdomains over so they can be modified.
384:       */
385:       PetscMalloc1(osm->n,&osm->ois);
386:       for (i=0; i<osm->n; ++i) {
387:         if (osm->overlap > 0 && osm->N>1) { /* With positive overlap, osm->iis[i] will be modified */
388:           ISDuplicate(osm->iis[i],(osm->ois)+i);
389:           ISCopy(osm->iis[i],osm->ois[i]);
390:         } else {
391:           PetscObjectReference((PetscObject)((osm->iis)[i]));
392:           osm->ois[i] = osm->iis[i];
393:         }
394:       }
395:       if (osm->overlap>0 && osm->N>1) {
396:         /* Extend the "overlapping" regions by a number of steps */
397:         MatIncreaseOverlapSplit(pc->pmat,osm->n,osm->ois,osm->overlap);
398:       }
399:     }

401:     /* Now the subdomains are defined.  Determine their global and max local numbers, if necessary. */
402:     if (osm->nmax == PETSC_DETERMINE) {
403:       PetscMPIInt inwork,outwork;
404:       /* determine global number of subdomains and the max number of local subdomains */
405:       inwork     = osm->n;
406:       MPIU_Allreduce(&inwork,&outwork,1,MPI_INT,MPI_MAX,PetscObjectComm((PetscObject)pc));
407:       osm->nmax  = outwork;
408:     }
409:     if (osm->N == PETSC_DETERMINE) {
410:       /* Determine the number of globally-distinct subdomains and compute a global numbering for them. */
411:       PetscObjectsListGetGlobalNumbering(PetscObjectComm((PetscObject)pc),osm->n,(PetscObject*)osm->ois,&osm->N,NULL);
412:     }

414:     if (osm->sort_indices) {
415:       for (i=0; i<osm->n; i++) {
416:         ISSort(osm->ois[i]);
417:         ISSort(osm->iis[i]);
418:       }
419:     }
420:     PCGetOptionsPrefix(pc,&prefix);
421:     PCGASMPrintSubdomains(pc);

423:     /*
424:        Merge the ISs, create merged vectors and restrictions.
425:      */
426:     /* Merge outer subdomain ISs and construct a restriction onto the disjoint union of local outer subdomains. */
427:     on = 0;
428:     for (i=0; i<osm->n; i++) {
429:       ISGetLocalSize(osm->ois[i],&oni);
430:       on  += oni;
431:     }
432:     PetscMalloc1(on, &oidx);
433:     on   = 0;
434:     /* Merge local indices together */
435:     for (i=0; i<osm->n; i++) {
436:       ISGetLocalSize(osm->ois[i],&oni);
437:       ISGetIndices(osm->ois[i],&oidxi);
438:       PetscArraycpy(oidx+on,oidxi,oni);
439:       ISRestoreIndices(osm->ois[i],&oidxi);
440:       on  += oni;
441:     }
442:     ISCreateGeneral(((PetscObject)(pc))->comm,on,oidx,PETSC_OWN_POINTER,&gois);
443:     nTotalInnerIndices = 0;
444:     for (i=0; i<osm->n; i++) {
445:       ISGetLocalSize(osm->iis[i],&nInnerIndices);
446:       nTotalInnerIndices += nInnerIndices;
447:     }
448:     VecCreateMPI(((PetscObject)(pc))->comm,nTotalInnerIndices,PETSC_DETERMINE,&x);
449:     VecDuplicate(x,&y);

451:     VecCreateMPI(PetscObjectComm((PetscObject)pc),on,PETSC_DECIDE,&osm->gx);
452:     VecDuplicate(osm->gx,&osm->gy);
453:     VecGetOwnershipRange(osm->gx, &gostart, NULL);
454:     ISCreateStride(PetscObjectComm((PetscObject)pc),on,gostart,1, &goid);
455:     /* gois might indices not on local */
456:     VecScatterCreate(x,gois,osm->gx,goid, &(osm->gorestriction));
457:     PetscMalloc1(osm->n,&numbering);
458:     PetscObjectsListGetGlobalNumbering(PetscObjectComm((PetscObject)pc),osm->n,(PetscObject*)osm->ois,NULL,numbering);
459:     VecDestroy(&x);
460:     ISDestroy(&gois);

462:     /* Merge inner subdomain ISs and construct a restriction onto the disjoint union of local inner subdomains. */
463:     {
464:       PetscInt        ini;           /* Number of indices the i-th a local inner subdomain. */
465:       PetscInt        in;            /* Number of indices in the disjoint union of local inner subdomains. */
466:       PetscInt       *iidx;          /* Global indices in the merged local inner subdomain. */
467:       PetscInt       *ioidx;         /* Global indices of the disjoint union of inner subdomains within the disjoint union of outer subdomains. */
468:       IS              giis;          /* IS for the disjoint union of inner subdomains. */
469:       IS              giois;         /* IS for the disjoint union of inner subdomains within the disjoint union of outer subdomains. */
470:       PetscScalar    *array;
471:       const PetscInt *indices;
472:       PetscInt        k;
473:       on = 0;
474:       for (i=0; i<osm->n; i++) {
475:         ISGetLocalSize(osm->ois[i],&oni);
476:         on  += oni;
477:       }
478:       PetscMalloc1(on, &iidx);
479:       PetscMalloc1(on, &ioidx);
480:       VecGetArray(y,&array);
481:       /* set communicator id to determine where overlap is */
482:       in   = 0;
483:       for (i=0; i<osm->n; i++) {
484:         ISGetLocalSize(osm->iis[i],&ini);
485:         for (k = 0; k < ini; ++k) {
486:           array[in+k] = numbering[i];
487:         }
488:         in += ini;
489:       }
490:       VecRestoreArray(y,&array);
491:       VecScatterBegin(osm->gorestriction,y,osm->gy,INSERT_VALUES,SCATTER_FORWARD);
492:       VecScatterEnd(osm->gorestriction,y,osm->gy,INSERT_VALUES,SCATTER_FORWARD);
493:       VecGetOwnershipRange(osm->gy,&gostart, NULL);
494:       VecGetArray(osm->gy,&array);
495:       on  = 0;
496:       in  = 0;
497:       for (i=0; i<osm->n; i++) {
498:         ISGetLocalSize(osm->ois[i],&oni);
499:         ISGetIndices(osm->ois[i],&indices);
500:         for (k=0; k<oni; k++) {
501:           /*  skip overlapping indices to get inner domain */
502:           if (PetscRealPart(array[on+k]) != numbering[i]) continue;
503:           iidx[in]    = indices[k];
504:           ioidx[in++] = gostart+on+k;
505:         }
506:         ISRestoreIndices(osm->ois[i], &indices);
507:         on += oni;
508:       }
509:       VecRestoreArray(osm->gy,&array);
510:       ISCreateGeneral(PetscObjectComm((PetscObject)pc),in,iidx,PETSC_OWN_POINTER,&giis);
511:       ISCreateGeneral(PetscObjectComm((PetscObject)pc),in,ioidx,PETSC_OWN_POINTER,&giois);
512:       VecScatterCreate(y,giis,osm->gy,giois,&osm->girestriction);
513:       VecDestroy(&y);
514:       ISDestroy(&giis);
515:       ISDestroy(&giois);
516:     }
517:     ISDestroy(&goid);
518:     PetscFree(numbering);

520:     /* Create the subdomain work vectors. */
521:     PetscMalloc1(osm->n,&osm->x);
522:     PetscMalloc1(osm->n,&osm->y);
523:     VecGetArray(osm->gx, &gxarray);
524:     VecGetArray(osm->gy, &gyarray);
525:     for (i=0, on=0; i<osm->n; ++i, on += oni) {
526:       PetscInt oNi;
527:       ISGetLocalSize(osm->ois[i],&oni);
528:       /* on a sub communicator */
529:       ISGetSize(osm->ois[i],&oNi);
530:       VecCreateMPIWithArray(((PetscObject)(osm->ois[i]))->comm,1,oni,oNi,gxarray+on,&osm->x[i]);
531:       VecCreateMPIWithArray(((PetscObject)(osm->ois[i]))->comm,1,oni,oNi,gyarray+on,&osm->y[i]);
532:     }
533:     VecRestoreArray(osm->gx, &gxarray);
534:     VecRestoreArray(osm->gy, &gyarray);
535:     /* Create the subdomain solvers */
536:     PetscMalloc1(osm->n,&osm->ksp);
537:     for (i=0; i<osm->n; i++) {
538:       char subprefix[PETSC_MAX_PATH_LEN+1];
539:       KSPCreate(((PetscObject)(osm->ois[i]))->comm,&ksp);
540:       KSPSetErrorIfNotConverged(ksp,pc->erroriffailure);
541:       PetscLogObjectParent((PetscObject)pc,(PetscObject)ksp);
542:       PetscObjectIncrementTabLevel((PetscObject)ksp,(PetscObject)pc,1);
543:       KSPSetType(ksp,KSPPREONLY);
544:       KSPGetPC(ksp,&subpc); /* Why do we need this here? */
545:       if (subdomain_dm) {
546:         KSPSetDM(ksp,subdomain_dm[i]);
547:         DMDestroy(subdomain_dm+i);
548:       }
549:       PCGetOptionsPrefix(pc,&prefix);
550:       KSPSetOptionsPrefix(ksp,prefix);
551:       if (subdomain_names && subdomain_names[i]) {
552:         PetscSNPrintf(subprefix,PETSC_MAX_PATH_LEN,"sub_%s_",subdomain_names[i]);
553:         KSPAppendOptionsPrefix(ksp,subprefix);
554:         PetscFree(subdomain_names[i]);
555:       }
556:       KSPAppendOptionsPrefix(ksp,"sub_");
557:       osm->ksp[i] = ksp;
558:     }
559:     PetscFree(subdomain_dm);
560:     PetscFree(subdomain_names);
561:     scall = MAT_INITIAL_MATRIX;
562:   } else { /* if (pc->setupcalled) */
563:     /*
564:        Destroy the submatrices from the previous iteration
565:     */
566:     if (pc->flag == DIFFERENT_NONZERO_PATTERN) {
567:       MatDestroyMatrices(osm->n,&osm->pmat);
568:       scall = MAT_INITIAL_MATRIX;
569:     }
570:     if (osm->permutationIS) {
571:       MatCreateSubMatrix(pc->pmat,osm->permutationIS,osm->permutationIS,scall,&osm->permutationP);
572:       PetscObjectReference((PetscObject)osm->permutationP);
573:       osm->pcmat = pc->pmat;
574:       pc->pmat   = osm->permutationP;
575:     }
576:   }

578:   /*
579:      Extract the submatrices.
580:   */
581:   if (size > 1) {
582:     MatCreateSubMatricesMPI(pc->pmat,osm->n,osm->ois,osm->ois,scall,&osm->pmat);
583:   } else {
584:     MatCreateSubMatrices(pc->pmat,osm->n,osm->ois,osm->ois,scall,&osm->pmat);
585:   }
586:   if (scall == MAT_INITIAL_MATRIX) {
587:     PetscObjectGetOptionsPrefix((PetscObject)pc->pmat,&pprefix);
588:     for (i=0; i<osm->n; i++) {
589:       PetscLogObjectParent((PetscObject)pc,(PetscObject)osm->pmat[i]);
590:       PetscObjectSetOptionsPrefix((PetscObject)osm->pmat[i],pprefix);
591:     }
592:   }

594:   /* Return control to the user so that the submatrices can be modified (e.g., to apply
595:      different boundary conditions for the submatrices than for the global problem) */
596:   PCModifySubMatrices(pc,osm->n,osm->ois,osm->ois,osm->pmat,pc->modifysubmatricesP);

598:   /*
599:      Loop over submatrices putting them into local ksps
600:   */
601:   for (i=0; i<osm->n; i++) {
602:     KSPSetOperators(osm->ksp[i],osm->pmat[i],osm->pmat[i]);
603:     KSPGetOptionsPrefix(osm->ksp[i],&prefix);
604:     MatSetOptionsPrefix(osm->pmat[i],prefix);
605:     if (!pc->setupcalled) {
606:       KSPSetFromOptions(osm->ksp[i]);
607:     }
608:   }
609:   if (osm->pcmat) {
610:     MatDestroy(&pc->pmat);
611:     pc->pmat   = osm->pcmat;
612:     osm->pcmat = NULL;
613:   }
614:   return(0);
615: }

617: static PetscErrorCode PCSetUpOnBlocks_GASM(PC pc)
618: {
619:   PC_GASM        *osm = (PC_GASM*)pc->data;
621:   PetscInt       i;

624:   for (i=0; i<osm->n; i++) {
625:     KSPSetUp(osm->ksp[i]);
626:   }
627:   return(0);
628: }

630: static PetscErrorCode PCApply_GASM(PC pc,Vec xin,Vec yout)
631: {
632:   PC_GASM        *osm = (PC_GASM*)pc->data;
634:   PetscInt       i;
635:   Vec            x,y;
636:   ScatterMode    forward = SCATTER_FORWARD,reverse = SCATTER_REVERSE;

639:   if (osm->pctoouter) {
640:     VecScatterBegin(osm->pctoouter,xin,osm->pcx,INSERT_VALUES,SCATTER_REVERSE);
641:     VecScatterEnd(osm->pctoouter,xin,osm->pcx,INSERT_VALUES,SCATTER_REVERSE);
642:     x = osm->pcx;
643:     y = osm->pcy;
644:   } else {
645:     x = xin;
646:     y = yout;
647:   }
648:   /*
649:      support for limiting the restriction or interpolation only to the inner
650:      subdomain values (leaving the other values 0).
651:   */
652:   if (!(osm->type & PC_GASM_RESTRICT)) {
653:     /* have to zero the work RHS since scatter may leave some slots empty */
654:     VecZeroEntries(osm->gx);
655:     VecScatterBegin(osm->girestriction,x,osm->gx,INSERT_VALUES,forward);
656:   } else {
657:     VecScatterBegin(osm->gorestriction,x,osm->gx,INSERT_VALUES,forward);
658:   }
659:   VecZeroEntries(osm->gy);
660:   if (!(osm->type & PC_GASM_RESTRICT)) {
661:     VecScatterEnd(osm->girestriction,x,osm->gx,INSERT_VALUES,forward);
662:   } else {
663:     VecScatterEnd(osm->gorestriction,x,osm->gx,INSERT_VALUES,forward);
664:   }
665:   /* do the subdomain solves */
666:   for (i=0; i<osm->n; ++i) {
667:     KSPSolve(osm->ksp[i],osm->x[i],osm->y[i]);
668:     KSPCheckSolve(osm->ksp[i],pc,osm->y[i]);
669:   }
670:   /* do we need to zero y? */
671:   VecZeroEntries(y);
672:   if (!(osm->type & PC_GASM_INTERPOLATE)) {
673:     VecScatterBegin(osm->girestriction,osm->gy,y,ADD_VALUES,reverse);
674:     VecScatterEnd(osm->girestriction,osm->gy,y,ADD_VALUES,reverse);
675:   } else {
676:     VecScatterBegin(osm->gorestriction,osm->gy,y,ADD_VALUES,reverse);
677:     VecScatterEnd(osm->gorestriction,osm->gy,y,ADD_VALUES,reverse);
678:   }
679:   if (osm->pctoouter) {
680:     VecScatterBegin(osm->pctoouter,y,yout,INSERT_VALUES,SCATTER_FORWARD);
681:     VecScatterEnd(osm->pctoouter,y,yout,INSERT_VALUES,SCATTER_FORWARD);
682:   }
683:   return(0);
684: }

686: static PetscErrorCode PCMatApply_GASM(PC pc,Mat Xin,Mat Yout)
687: {
688:   PC_GASM        *osm = (PC_GASM*)pc->data;
689:   Mat            X,Y,O=NULL,Z,W;
690:   Vec            x,y;
691:   PetscInt       i,m,M,N;
692:   ScatterMode    forward = SCATTER_FORWARD,reverse = SCATTER_REVERSE;

696:   if (osm->n != 1) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Not yet implemented");
697:   MatGetSize(Xin,NULL,&N);
698:   if (osm->pctoouter) {
699:     VecGetLocalSize(osm->pcx,&m);
700:     VecGetSize(osm->pcx,&M);
701:     MatCreateDense(PetscObjectComm((PetscObject)osm->ois[0]),m,PETSC_DECIDE,M,N,NULL,&O);
702:     for (i = 0; i < N; ++i) {
703:       MatDenseGetColumnVecRead(Xin,i,&x);
704:       MatDenseGetColumnVecWrite(O,i,&y);
705:       VecScatterBegin(osm->pctoouter,x,y,INSERT_VALUES,SCATTER_REVERSE);
706:       VecScatterEnd(osm->pctoouter,x,y,INSERT_VALUES,SCATTER_REVERSE);
707:       MatDenseRestoreColumnVecWrite(O,i,&y);
708:       MatDenseRestoreColumnVecRead(Xin,i,&x);
709:     }
710:     X = Y = O;
711:   } else {
712:     X = Xin;
713:     Y = Yout;
714:   }
715:   /*
716:      support for limiting the restriction or interpolation only to the inner
717:      subdomain values (leaving the other values 0).
718:   */
719:   VecGetLocalSize(osm->x[0],&m);
720:   VecGetSize(osm->x[0],&M);
721:   MatCreateDense(PetscObjectComm((PetscObject)osm->ois[0]),m,PETSC_DECIDE,M,N,NULL,&Z);
722:   for (i = 0; i < N; ++i) {
723:     MatDenseGetColumnVecRead(X,i,&x);
724:     MatDenseGetColumnVecWrite(Z,i,&y);
725:     if (!(osm->type & PC_GASM_RESTRICT)) {
726:       /* have to zero the work RHS since scatter may leave some slots empty */
727:       VecZeroEntries(y);
728:       VecScatterBegin(osm->girestriction,x,y,INSERT_VALUES,forward);
729:       VecScatterEnd(osm->girestriction,x,y,INSERT_VALUES,forward);
730:     } else {
731:       VecScatterBegin(osm->gorestriction,x,y,INSERT_VALUES,forward);
732:       VecScatterEnd(osm->gorestriction,x,y,INSERT_VALUES,forward);
733:     }
734:     MatDenseRestoreColumnVecWrite(Z,i,&y);
735:     MatDenseRestoreColumnVecRead(X,i,&x);
736:   }
737:   MatCreateDense(PetscObjectComm((PetscObject)osm->ois[0]),m,PETSC_DECIDE,M,N,NULL,&W);
738:   MatSetOption(Z,MAT_NO_OFF_PROC_ENTRIES,PETSC_TRUE);
739:   MatAssemblyBegin(Z,MAT_FINAL_ASSEMBLY);
740:   MatAssemblyEnd(Z,MAT_FINAL_ASSEMBLY);
741:   /* do the subdomain solve */
742:   KSPMatSolve(osm->ksp[0],Z,W);
743:   KSPCheckSolve(osm->ksp[0],pc,NULL);
744:   MatDestroy(&Z);
745:   /* do we need to zero y? */
746:   MatZeroEntries(Y);
747:   for (i = 0; i < N; ++i) {
748:     MatDenseGetColumnVecWrite(Y,i,&y);
749:     MatDenseGetColumnVecRead(W,i,&x);
750:     if (!(osm->type & PC_GASM_INTERPOLATE)) {
751:       VecScatterBegin(osm->girestriction,x,y,ADD_VALUES,reverse);
752:       VecScatterEnd(osm->girestriction,x,y,ADD_VALUES,reverse);
753:     } else {
754:       VecScatterBegin(osm->gorestriction,x,y,ADD_VALUES,reverse);
755:       VecScatterEnd(osm->gorestriction,x,y,ADD_VALUES,reverse);
756:     }
757:     MatDenseRestoreColumnVecRead(W,i,&x);
758:     if (osm->pctoouter) {
759:       MatDenseGetColumnVecWrite(Yout,i,&x);
760:       VecScatterBegin(osm->pctoouter,y,x,INSERT_VALUES,SCATTER_FORWARD);
761:       VecScatterEnd(osm->pctoouter,y,x,INSERT_VALUES,SCATTER_FORWARD);
762:       MatDenseRestoreColumnVecRead(Yout,i,&x);
763:     }
764:     MatDenseRestoreColumnVecWrite(Y,i,&y);
765:   }
766:   MatDestroy(&W);
767:   MatDestroy(&O);
768:   return(0);
769: }

771: static PetscErrorCode PCApplyTranspose_GASM(PC pc,Vec xin,Vec yout)
772: {
773:   PC_GASM        *osm = (PC_GASM*)pc->data;
775:   PetscInt       i;
776:   Vec            x,y;
777:   ScatterMode    forward = SCATTER_FORWARD,reverse = SCATTER_REVERSE;

780:   if (osm->pctoouter) {
781:    VecScatterBegin(osm->pctoouter,xin,osm->pcx,INSERT_VALUES,SCATTER_REVERSE);
782:    VecScatterEnd(osm->pctoouter,xin,osm->pcx,INSERT_VALUES,SCATTER_REVERSE);
783:    x = osm->pcx;
784:    y = osm->pcy;
785:   }else{
786:         x = xin;
787:         y = yout;
788:   }
789:   /*
790:      Support for limiting the restriction or interpolation to only local
791:      subdomain values (leaving the other values 0).

793:      Note: these are reversed from the PCApply_GASM() because we are applying the
794:      transpose of the three terms
795:   */
796:   if (!(osm->type & PC_GASM_INTERPOLATE)) {
797:     /* have to zero the work RHS since scatter may leave some slots empty */
798:     VecZeroEntries(osm->gx);
799:     VecScatterBegin(osm->girestriction,x,osm->gx,INSERT_VALUES,forward);
800:   } else {
801:     VecScatterBegin(osm->gorestriction,x,osm->gx,INSERT_VALUES,forward);
802:   }
803:   VecZeroEntries(osm->gy);
804:   if (!(osm->type & PC_GASM_INTERPOLATE)) {
805:     VecScatterEnd(osm->girestriction,x,osm->gx,INSERT_VALUES,forward);
806:   } else {
807:     VecScatterEnd(osm->gorestriction,x,osm->gx,INSERT_VALUES,forward);
808:   }
809:   /* do the local solves */
810:   for (i=0; i<osm->n; ++i) { /* Note that the solves are local, so we can go to osm->n, rather than osm->nmax. */
811:     KSPSolveTranspose(osm->ksp[i],osm->x[i],osm->y[i]);
812:     KSPCheckSolve(osm->ksp[i],pc,osm->y[i]);
813:   }
814:   VecZeroEntries(y);
815:   if (!(osm->type & PC_GASM_RESTRICT)) {
816:     VecScatterBegin(osm->girestriction,osm->gy,y,ADD_VALUES,reverse);
817:     VecScatterEnd(osm->girestriction,osm->gy,y,ADD_VALUES,reverse);
818:   } else {
819:     VecScatterBegin(osm->gorestriction,osm->gy,y,ADD_VALUES,reverse);
820:     VecScatterEnd(osm->gorestriction,osm->gy,y,ADD_VALUES,reverse);
821:   }
822:   if (osm->pctoouter) {
823:    VecScatterBegin(osm->pctoouter,y,yout,INSERT_VALUES,SCATTER_FORWARD);
824:    VecScatterEnd(osm->pctoouter,y,yout,INSERT_VALUES,SCATTER_FORWARD);
825:   }
826:   return(0);
827: }

829: static PetscErrorCode PCReset_GASM(PC pc)
830: {
831:   PC_GASM        *osm = (PC_GASM*)pc->data;
833:   PetscInt       i;

836:   if (osm->ksp) {
837:     for (i=0; i<osm->n; i++) {
838:       KSPReset(osm->ksp[i]);
839:     }
840:   }
841:   if (osm->pmat) {
842:     if (osm->n > 0) {
843:       PetscMPIInt size;
844:       MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
845:       if (size > 1) {
846:         /* osm->pmat is created by MatCreateSubMatricesMPI(), cannot use MatDestroySubMatrices() */
847:         MatDestroyMatrices(osm->n,&osm->pmat);
848:       } else {
849:         MatDestroySubMatrices(osm->n,&osm->pmat);
850:       }
851:     }
852:   }
853:   if (osm->x) {
854:     for (i=0; i<osm->n; i++) {
855:       VecDestroy(&osm->x[i]);
856:       VecDestroy(&osm->y[i]);
857:     }
858:   }
859:   VecDestroy(&osm->gx);
860:   VecDestroy(&osm->gy);

862:   VecScatterDestroy(&osm->gorestriction);
863:   VecScatterDestroy(&osm->girestriction);
864:   if (!osm->user_subdomains) {
865:     PCGASMDestroySubdomains(osm->n,&osm->ois,&osm->iis);
866:     osm->N    = PETSC_DETERMINE;
867:     osm->nmax = PETSC_DETERMINE;
868:   }
869:   if (osm->pctoouter) {
870:         VecScatterDestroy(&(osm->pctoouter));
871:   }
872:   if (osm->permutationIS) {
873:         ISDestroy(&(osm->permutationIS));
874:   }
875:   if (osm->pcx) {
876:         VecDestroy(&(osm->pcx));
877:   }
878:   if (osm->pcy) {
879:         VecDestroy(&(osm->pcy));
880:   }
881:   if (osm->permutationP) {
882:     MatDestroy(&(osm->permutationP));
883:   }
884:   if (osm->pcmat) {
885:         MatDestroy(&osm->pcmat);
886:   }
887:   return(0);
888: }

890: static PetscErrorCode PCDestroy_GASM(PC pc)
891: {
892:   PC_GASM        *osm = (PC_GASM*)pc->data;
894:   PetscInt       i;

897:   PCReset_GASM(pc);
898:   /* PCReset will not destroy subdomains, if user_subdomains is true. */
899:   PCGASMDestroySubdomains(osm->n,&osm->ois,&osm->iis);
900:   if (osm->ksp) {
901:     for (i=0; i<osm->n; i++) {
902:       KSPDestroy(&osm->ksp[i]);
903:     }
904:     PetscFree(osm->ksp);
905:   }
906:   PetscFree(osm->x);
907:   PetscFree(osm->y);
908:   PetscFree(pc->data);
909:   return(0);
910: }

912: static PetscErrorCode PCSetFromOptions_GASM(PetscOptionItems *PetscOptionsObject,PC pc)
913: {
914:   PC_GASM        *osm = (PC_GASM*)pc->data;
916:   PetscInt       blocks,ovl;
917:   PetscBool      flg;
918:   PCGASMType     gasmtype;

921:   PetscOptionsHead(PetscOptionsObject,"Generalized additive Schwarz options");
922:   PetscOptionsBool("-pc_gasm_use_dm_subdomains","If subdomains aren't set, use DMCreateDomainDecomposition() to define subdomains.","PCGASMSetUseDMSubdomains",osm->dm_subdomains,&osm->dm_subdomains,&flg);
923:   PetscOptionsInt("-pc_gasm_total_subdomains","Total number of subdomains across communicator","PCGASMSetTotalSubdomains",osm->N,&blocks,&flg);
924:   if (flg) {
925:     PCGASMSetTotalSubdomains(pc,blocks);
926:   }
927:   PetscOptionsInt("-pc_gasm_overlap","Number of overlapping degrees of freedom","PCGASMSetOverlap",osm->overlap,&ovl,&flg);
928:   if (flg) {
929:     PCGASMSetOverlap(pc,ovl);
930:     osm->dm_subdomains = PETSC_FALSE;
931:   }
932:   flg  = PETSC_FALSE;
933:   PetscOptionsEnum("-pc_gasm_type","Type of restriction/extension","PCGASMSetType",PCGASMTypes,(PetscEnum)osm->type,(PetscEnum*)&gasmtype,&flg);
934:   if (flg) {PCGASMSetType(pc,gasmtype);}
935:   PetscOptionsBool("-pc_gasm_use_hierachical_partitioning","use hierarchical partitioning",NULL,osm->hierarchicalpartitioning,&osm->hierarchicalpartitioning,&flg);
936:   PetscOptionsTail();
937:   return(0);
938: }

940: /*------------------------------------------------------------------------------------*/

942: /*@
943:     PCGASMSetTotalSubdomains - sets the total number of subdomains to use across the
944:                                communicator.
945:     Logically collective on pc

947:     Input Parameters:
948: +   pc  - the preconditioner
949: -   N   - total number of subdomains

951:     Level: beginner

953: .seealso: PCGASMSetSubdomains(), PCGASMSetOverlap()
954:           PCGASMCreateSubdomains2D()
955: @*/
956: PetscErrorCode  PCGASMSetTotalSubdomains(PC pc,PetscInt N)
957: {
958:   PC_GASM        *osm = (PC_GASM*)pc->data;
959:   PetscMPIInt    size,rank;

963:   if (N < 1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Total number of subdomains must be 1 or more, got N = %D",N);
964:   if (pc->setupcalled) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"PCGASMSetTotalSubdomains() should be called before calling PCSetUp().");

966:   PCGASMDestroySubdomains(osm->n,&osm->iis,&osm->ois);
967:   osm->ois = osm->iis = NULL;

969:   MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
970:   MPI_Comm_rank(PetscObjectComm((PetscObject)pc),&rank);
971:   osm->N    = N;
972:   osm->n    = PETSC_DETERMINE;
973:   osm->nmax = PETSC_DETERMINE;
974:   osm->dm_subdomains = PETSC_FALSE;
975:   return(0);
976: }

978: static PetscErrorCode  PCGASMSetSubdomains_GASM(PC pc,PetscInt n,IS iis[],IS ois[])
979: {
980:   PC_GASM         *osm = (PC_GASM*)pc->data;
981:   PetscErrorCode  ierr;
982:   PetscInt        i;

985:   if (n < 1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Each process must have 1 or more subdomains, got n = %D",n);
986:   if (pc->setupcalled) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"PCGASMSetSubdomains() should be called before calling PCSetUp().");

988:   PCGASMDestroySubdomains(osm->n,&osm->iis,&osm->ois);
989:   osm->iis  = osm->ois = NULL;
990:   osm->n    = n;
991:   osm->N    = PETSC_DETERMINE;
992:   osm->nmax = PETSC_DETERMINE;
993:   if (ois) {
994:     PetscMalloc1(n,&osm->ois);
995:     for (i=0; i<n; i++) {
996:       PetscObjectReference((PetscObject)ois[i]);
997:       osm->ois[i] = ois[i];
998:     }
999:     /*
1000:        Since the user set the outer subdomains, even if nontrivial overlap was requested via PCGASMSetOverlap(),
1001:        it will be ignored.  To avoid confusion later on (e.g., when viewing the PC), the overlap size is set to -1.
1002:     */
1003:     osm->overlap = -1;
1004:     /* inner subdomains must be provided  */
1005:     if (!iis) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_NULL,"inner indices have to be provided \n");
1006:   }/* end if */
1007:   if (iis) {
1008:     PetscMalloc1(n,&osm->iis);
1009:     for (i=0; i<n; i++) {
1010:       PetscObjectReference((PetscObject)iis[i]);
1011:       osm->iis[i] = iis[i];
1012:     }
1013:     if (!ois) {
1014:       osm->ois = NULL;
1015:       /* if user does not provide outer indices, we will create the corresponding outer indices using  osm->overlap =1 in PCSetUp_GASM */
1016:     }
1017:   }
1018:   if (PetscDefined(USE_DEBUG)) {
1019:     PetscInt        j,rstart,rend,*covered,lsize;
1020:     const PetscInt  *indices;
1021:     /* check if the inner indices cover and only cover the local portion of the preconditioning matrix */
1022:     MatGetOwnershipRange(pc->pmat,&rstart,&rend);
1023:     PetscCalloc1(rend-rstart,&covered);
1024:     /* check if the current processor owns indices from others */
1025:     for (i=0; i<n; i++) {
1026:       ISGetIndices(osm->iis[i],&indices);
1027:       ISGetLocalSize(osm->iis[i],&lsize);
1028:       for (j=0; j<lsize; j++) {
1029:         if (indices[j]<rstart || indices[j]>=rend) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"inner subdomains can not own an index %d from other processors", indices[j]);
1030:         else if (covered[indices[j]-rstart]==1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"inner subdomains can not have an overlapping index %d ",indices[j]);
1031:         else covered[indices[j]-rstart] = 1;
1032:       }
1033:     ISRestoreIndices(osm->iis[i],&indices);
1034:     }
1035:     /* check if we miss any indices */
1036:     for (i=rstart; i<rend; i++) {
1037:       if (!covered[i-rstart]) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_NULL,"local entity %d was not covered by inner subdomains",i);
1038:     }
1039:     PetscFree(covered);
1040:   }
1041:   if (iis)  osm->user_subdomains = PETSC_TRUE;
1042:   return(0);
1043: }

1045: static PetscErrorCode  PCGASMSetOverlap_GASM(PC pc,PetscInt ovl)
1046: {
1047:   PC_GASM *osm = (PC_GASM*)pc->data;

1050:   if (ovl < 0) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_OUTOFRANGE,"Negative overlap value requested");
1051:   if (pc->setupcalled && ovl != osm->overlap) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"PCGASMSetOverlap() should be called before PCSetUp().");
1052:   if (!pc->setupcalled) osm->overlap = ovl;
1053:   return(0);
1054: }

1056: static PetscErrorCode  PCGASMSetType_GASM(PC pc,PCGASMType type)
1057: {
1058:   PC_GASM *osm = (PC_GASM*)pc->data;

1061:   osm->type     = type;
1062:   osm->type_set = PETSC_TRUE;
1063:   return(0);
1064: }

1066: static PetscErrorCode  PCGASMSetSortIndices_GASM(PC pc,PetscBool doSort)
1067: {
1068:   PC_GASM *osm = (PC_GASM*)pc->data;

1071:   osm->sort_indices = doSort;
1072:   return(0);
1073: }

1075: /*
1076:    FIXME: This routine might need to be modified now that multiple ranks per subdomain are allowed.
1077:         In particular, it would upset the global subdomain number calculation.
1078: */
1079: static PetscErrorCode  PCGASMGetSubKSP_GASM(PC pc,PetscInt *n,PetscInt *first,KSP **ksp)
1080: {
1081:   PC_GASM        *osm = (PC_GASM*)pc->data;

1085:   if (osm->n < 1) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ORDER,"Need to call PCSetUp() on PC (or KSPSetUp() on the outer KSP object) before calling here");

1087:   if (n) *n = osm->n;
1088:   if (first) {
1089:     MPI_Scan(&osm->n,first,1,MPIU_INT,MPI_SUM,PetscObjectComm((PetscObject)pc));
1090:     *first -= osm->n;
1091:   }
1092:   if (ksp) {
1093:     /* Assume that local solves are now different; not necessarily
1094:        true, though!  This flag is used only for PCView_GASM() */
1095:     *ksp                        = osm->ksp;
1096:     osm->same_subdomain_solvers = PETSC_FALSE;
1097:   }
1098:   return(0);
1099: } /* PCGASMGetSubKSP_GASM() */

1101: /*@C
1102:     PCGASMSetSubdomains - Sets the subdomains for this processor
1103:     for the additive Schwarz preconditioner.

1105:     Collective on pc

1107:     Input Parameters:
1108: +   pc  - the preconditioner object
1109: .   n   - the number of subdomains for this processor
1110: .   iis - the index sets that define the inner subdomains (or NULL for PETSc to determine subdomains)
1111: -   ois - the index sets that define the outer subdomains (or NULL to use the same as iis, or to construct by expanding iis by the requested overlap)

1113:     Notes:
1114:     The IS indices use the parallel, global numbering of the vector entries.
1115:     Inner subdomains are those where the correction is applied.
1116:     Outer subdomains are those where the residual necessary to obtain the
1117:     corrections is obtained (see PCGASMType for the use of inner/outer subdomains).
1118:     Both inner and outer subdomains can extend over several processors.
1119:     This processor's portion of a subdomain is known as a local subdomain.

1121:     Inner subdomains can not overlap with each other, do not have any entities from remote processors,
1122:     and  have to cover the entire local subdomain owned by the current processor. The index sets on each
1123:     process should be ordered such that the ith local subdomain is connected to the ith remote subdomain
1124:     on another MPI process.

1126:     By default the GASM preconditioner uses 1 (local) subdomain per processor.

1128:     Level: advanced

1130: .seealso: PCGASMSetOverlap(), PCGASMGetSubKSP(),
1131:           PCGASMCreateSubdomains2D(), PCGASMGetSubdomains()
1132: @*/
1133: PetscErrorCode  PCGASMSetSubdomains(PC pc,PetscInt n,IS iis[],IS ois[])
1134: {
1135:   PC_GASM *osm = (PC_GASM*)pc->data;

1140:   PetscTryMethod(pc,"PCGASMSetSubdomains_C",(PC,PetscInt,IS[],IS[]),(pc,n,iis,ois));
1141:   osm->dm_subdomains = PETSC_FALSE;
1142:   return(0);
1143: }

1145: /*@
1146:     PCGASMSetOverlap - Sets the overlap between a pair of subdomains for the
1147:     additive Schwarz preconditioner.  Either all or no processors in the
1148:     pc communicator must call this routine.

1150:     Logically Collective on pc

1152:     Input Parameters:
1153: +   pc  - the preconditioner context
1154: -   ovl - the amount of overlap between subdomains (ovl >= 0, default value = 0)

1156:     Options Database Key:
1157: .   -pc_gasm_overlap <overlap> - Sets overlap

1159:     Notes:
1160:     By default the GASM preconditioner uses 1 subdomain per processor.  To use
1161:     multiple subdomain per perocessor or "straddling" subdomains that intersect
1162:     multiple processors use PCGASMSetSubdomains() (or option -pc_gasm_total_subdomains <n>).

1164:     The overlap defaults to 0, so if one desires that no additional
1165:     overlap be computed beyond what may have been set with a call to
1166:     PCGASMSetSubdomains(), then ovl must be set to be 0.  In particular, if one does
1167:     not explicitly set the subdomains in application code, then all overlap would be computed
1168:     internally by PETSc, and using an overlap of 0 would result in an GASM
1169:     variant that is equivalent to the block Jacobi preconditioner.

1171:     Note that one can define initial index sets with any overlap via
1172:     PCGASMSetSubdomains(); the routine PCGASMSetOverlap() merely allows
1173:     PETSc to extend that overlap further, if desired.

1175:     Level: intermediate

1177: .seealso: PCGASMSetSubdomains(), PCGASMGetSubKSP(),
1178:           PCGASMCreateSubdomains2D(), PCGASMGetSubdomains()
1179: @*/
1180: PetscErrorCode  PCGASMSetOverlap(PC pc,PetscInt ovl)
1181: {
1183:   PC_GASM *osm = (PC_GASM*)pc->data;

1188:   PetscTryMethod(pc,"PCGASMSetOverlap_C",(PC,PetscInt),(pc,ovl));
1189:   osm->dm_subdomains = PETSC_FALSE;
1190:   return(0);
1191: }

1193: /*@
1194:     PCGASMSetType - Sets the type of restriction and interpolation used
1195:     for local problems in the additive Schwarz method.

1197:     Logically Collective on PC

1199:     Input Parameters:
1200: +   pc  - the preconditioner context
1201: -   type - variant of GASM, one of
1202: .vb
1203:       PC_GASM_BASIC       - full interpolation and restriction
1204:       PC_GASM_RESTRICT    - full restriction, local processor interpolation
1205:       PC_GASM_INTERPOLATE - full interpolation, local processor restriction
1206:       PC_GASM_NONE        - local processor restriction and interpolation
1207: .ve

1209:     Options Database Key:
1210: .   -pc_gasm_type [basic,restrict,interpolate,none] - Sets GASM type

1212:     Level: intermediate

1214: .seealso: PCGASMSetSubdomains(), PCGASMGetSubKSP(),
1215:           PCGASMCreateSubdomains2D()
1216: @*/
1217: PetscErrorCode  PCGASMSetType(PC pc,PCGASMType type)
1218: {

1224:   PetscTryMethod(pc,"PCGASMSetType_C",(PC,PCGASMType),(pc,type));
1225:   return(0);
1226: }

1228: /*@
1229:     PCGASMSetSortIndices - Determines whether subdomain indices are sorted.

1231:     Logically Collective on PC

1233:     Input Parameters:
1234: +   pc  - the preconditioner context
1235: -   doSort - sort the subdomain indices

1237:     Level: intermediate

1239: .seealso: PCGASMSetSubdomains(), PCGASMGetSubKSP(),
1240:           PCGASMCreateSubdomains2D()
1241: @*/
1242: PetscErrorCode  PCGASMSetSortIndices(PC pc,PetscBool doSort)
1243: {

1249:   PetscTryMethod(pc,"PCGASMSetSortIndices_C",(PC,PetscBool),(pc,doSort));
1250:   return(0);
1251: }

1253: /*@C
1254:    PCGASMGetSubKSP - Gets the local KSP contexts for all blocks on
1255:    this processor.

1257:    Collective on PC iff first_local is requested

1259:    Input Parameter:
1260: .  pc - the preconditioner context

1262:    Output Parameters:
1263: +  n_local - the number of blocks on this processor or NULL
1264: .  first_local - the global number of the first block on this processor or NULL,
1265:                  all processors must request or all must pass NULL
1266: -  ksp - the array of KSP contexts

1268:    Note:
1269:    After PCGASMGetSubKSP() the array of KSPes is not to be freed

1271:    Currently for some matrix implementations only 1 block per processor
1272:    is supported.

1274:    You must call KSPSetUp() before calling PCGASMGetSubKSP().

1276:    Level: advanced

1278: .seealso: PCGASMSetSubdomains(), PCGASMSetOverlap(),
1279:           PCGASMCreateSubdomains2D(),
1280: @*/
1281: PetscErrorCode  PCGASMGetSubKSP(PC pc,PetscInt *n_local,PetscInt *first_local,KSP *ksp[])
1282: {

1287:   PetscUseMethod(pc,"PCGASMGetSubKSP_C",(PC,PetscInt*,PetscInt*,KSP **),(pc,n_local,first_local,ksp));
1288:   return(0);
1289: }

1291: /* -------------------------------------------------------------------------------------*/
1292: /*MC
1293:    PCGASM - Use the (restricted) additive Schwarz method, each block is (approximately) solved with
1294:            its own KSP object.

1296:    Options Database Keys:
1297: +  -pc_gasm_total_subdomains <n>  - Sets total number of local subdomains to be distributed among processors
1298: .  -pc_gasm_view_subdomains       - activates the printing of subdomain indices in PCView(), -ksp_view or -snes_view
1299: .  -pc_gasm_print_subdomains      - activates the printing of subdomain indices in PCSetUp()
1300: .  -pc_gasm_overlap <ovl>         - Sets overlap by which to (automatically) extend local subdomains
1301: -  -pc_gasm_type [basic,restrict,interpolate,none] - Sets GASM type

1303:      IMPORTANT: If you run with, for example, 3 blocks on 1 processor or 3 blocks on 3 processors you
1304:       will get a different convergence rate due to the default option of -pc_gasm_type restrict. Use
1305:       -pc_gasm_type basic to use the standard GASM.

1307:    Notes:
1308:     Blocks can be shared by multiple processes.

1310:      To set options on the solvers for each block append -sub_ to all the KSP, and PC
1311:         options database keys. For example, -sub_pc_type ilu -sub_pc_factor_levels 1 -sub_ksp_type preonly

1313:      To set the options on the solvers separate for each block call PCGASMGetSubKSP()
1314:          and set the options directly on the resulting KSP object (you can access its PC
1315:          with KSPGetPC())

1317:    Level: beginner

1319:     References:
1320: +   1. - M Dryja, OB Widlund, An additive variant of the Schwarz alternating method for the case of many subregions
1321:      Courant Institute, New York University Technical report
1322: -   2. - Barry Smith, Petter Bjorstad, and William Gropp, Domain Decompositions: Parallel Multilevel Methods for Elliptic Partial Differential Equations,
1323:     Cambridge University Press.

1325: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC,
1326:            PCBJACOBI,  PCGASMGetSubKSP(), PCGASMSetSubdomains(),
1327:            PCSetModifySubMatrices(), PCGASMSetOverlap(), PCGASMSetType()

1329: M*/

1331: PETSC_EXTERN PetscErrorCode PCCreate_GASM(PC pc)
1332: {
1334:   PC_GASM        *osm;

1337:   PetscNewLog(pc,&osm);

1339:   osm->N                        = PETSC_DETERMINE;
1340:   osm->n                        = PETSC_DECIDE;
1341:   osm->nmax                     = PETSC_DETERMINE;
1342:   osm->overlap                  = 0;
1343:   osm->ksp                      = NULL;
1344:   osm->gorestriction            = NULL;
1345:   osm->girestriction            = NULL;
1346:   osm->pctoouter                = NULL;
1347:   osm->gx                       = NULL;
1348:   osm->gy                       = NULL;
1349:   osm->x                        = NULL;
1350:   osm->y                        = NULL;
1351:   osm->pcx                      = NULL;
1352:   osm->pcy                      = NULL;
1353:   osm->permutationIS            = NULL;
1354:   osm->permutationP             = NULL;
1355:   osm->pcmat                    = NULL;
1356:   osm->ois                      = NULL;
1357:   osm->iis                      = NULL;
1358:   osm->pmat                     = NULL;
1359:   osm->type                     = PC_GASM_RESTRICT;
1360:   osm->same_subdomain_solvers   = PETSC_TRUE;
1361:   osm->sort_indices             = PETSC_TRUE;
1362:   osm->dm_subdomains            = PETSC_FALSE;
1363:   osm->hierarchicalpartitioning = PETSC_FALSE;

1365:   pc->data                 = (void*)osm;
1366:   pc->ops->apply           = PCApply_GASM;
1367:   pc->ops->matapply        = PCMatApply_GASM;
1368:   pc->ops->applytranspose  = PCApplyTranspose_GASM;
1369:   pc->ops->setup           = PCSetUp_GASM;
1370:   pc->ops->reset           = PCReset_GASM;
1371:   pc->ops->destroy         = PCDestroy_GASM;
1372:   pc->ops->setfromoptions  = PCSetFromOptions_GASM;
1373:   pc->ops->setuponblocks   = PCSetUpOnBlocks_GASM;
1374:   pc->ops->view            = PCView_GASM;
1375:   pc->ops->applyrichardson = NULL;

1377:   PetscObjectComposeFunction((PetscObject)pc,"PCGASMSetSubdomains_C",PCGASMSetSubdomains_GASM);
1378:   PetscObjectComposeFunction((PetscObject)pc,"PCGASMSetOverlap_C",PCGASMSetOverlap_GASM);
1379:   PetscObjectComposeFunction((PetscObject)pc,"PCGASMSetType_C",PCGASMSetType_GASM);
1380:   PetscObjectComposeFunction((PetscObject)pc,"PCGASMSetSortIndices_C",PCGASMSetSortIndices_GASM);
1381:   PetscObjectComposeFunction((PetscObject)pc,"PCGASMGetSubKSP_C",PCGASMGetSubKSP_GASM);
1382:   return(0);
1383: }

1385: PetscErrorCode  PCGASMCreateLocalSubdomains(Mat A, PetscInt nloc, IS *iis[])
1386: {
1387:   MatPartitioning mpart;
1388:   const char      *prefix;
1389:   PetscInt        i,j,rstart,rend,bs;
1390:   PetscBool       hasop, isbaij = PETSC_FALSE,foundpart = PETSC_FALSE;
1391:   Mat             Ad     = NULL, adj;
1392:   IS              ispart,isnumb,*is;
1393:   PetscErrorCode  ierr;

1396:   if (nloc < 1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"number of local subdomains must > 0, got nloc = %D",nloc);

1398:   /* Get prefix, row distribution, and block size */
1399:   MatGetOptionsPrefix(A,&prefix);
1400:   MatGetOwnershipRange(A,&rstart,&rend);
1401:   MatGetBlockSize(A,&bs);
1402:   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);

1404:   /* Get diagonal block from matrix if possible */
1405:   MatHasOperation(A,MATOP_GET_DIAGONAL_BLOCK,&hasop);
1406:   if (hasop) {
1407:     MatGetDiagonalBlock(A,&Ad);
1408:   }
1409:   if (Ad) {
1410:     PetscObjectBaseTypeCompare((PetscObject)Ad,MATSEQBAIJ,&isbaij);
1411:     if (!isbaij) {PetscObjectBaseTypeCompare((PetscObject)Ad,MATSEQSBAIJ,&isbaij);}
1412:   }
1413:   if (Ad && nloc > 1) {
1414:     PetscBool  match,done;
1415:     /* Try to setup a good matrix partitioning if available */
1416:     MatPartitioningCreate(PETSC_COMM_SELF,&mpart);
1417:     PetscObjectSetOptionsPrefix((PetscObject)mpart,prefix);
1418:     MatPartitioningSetFromOptions(mpart);
1419:     PetscObjectTypeCompare((PetscObject)mpart,MATPARTITIONINGCURRENT,&match);
1420:     if (!match) {
1421:       PetscObjectTypeCompare((PetscObject)mpart,MATPARTITIONINGSQUARE,&match);
1422:     }
1423:     if (!match) { /* assume a "good" partitioner is available */
1424:       PetscInt       na;
1425:       const PetscInt *ia,*ja;
1426:       MatGetRowIJ(Ad,0,PETSC_TRUE,isbaij,&na,&ia,&ja,&done);
1427:       if (done) {
1428:         /* Build adjacency matrix by hand. Unfortunately a call to
1429:            MatConvert(Ad,MATMPIADJ,MAT_INITIAL_MATRIX,&adj) will
1430:            remove the block-aij structure and we cannot expect
1431:            MatPartitioning to split vertices as we need */
1432:         PetscInt       i,j,len,nnz,cnt,*iia=NULL,*jja=NULL;
1433:         const PetscInt *row;
1434:         nnz = 0;
1435:         for (i=0; i<na; i++) { /* count number of nonzeros */
1436:           len = ia[i+1] - ia[i];
1437:           row = ja + ia[i];
1438:           for (j=0; j<len; j++) {
1439:             if (row[j] == i) { /* don't count diagonal */
1440:               len--; break;
1441:             }
1442:           }
1443:           nnz += len;
1444:         }
1445:         PetscMalloc1(na+1,&iia);
1446:         PetscMalloc1(nnz,&jja);
1447:         nnz    = 0;
1448:         iia[0] = 0;
1449:         for (i=0; i<na; i++) { /* fill adjacency */
1450:           cnt = 0;
1451:           len = ia[i+1] - ia[i];
1452:           row = ja + ia[i];
1453:           for (j=0; j<len; j++) {
1454:             if (row[j] != i) jja[nnz+cnt++] = row[j]; /* if not diagonal */
1455:           }
1456:           nnz += cnt;
1457:           iia[i+1] = nnz;
1458:         }
1459:         /* Partitioning of the adjacency matrix */
1460:         MatCreateMPIAdj(PETSC_COMM_SELF,na,na,iia,jja,NULL,&adj);
1461:         MatPartitioningSetAdjacency(mpart,adj);
1462:         MatPartitioningSetNParts(mpart,nloc);
1463:         MatPartitioningApply(mpart,&ispart);
1464:         ISPartitioningToNumbering(ispart,&isnumb);
1465:         MatDestroy(&adj);
1466:         foundpart = PETSC_TRUE;
1467:       }
1468:       MatRestoreRowIJ(Ad,0,PETSC_TRUE,isbaij,&na,&ia,&ja,&done);
1469:     }
1470:     MatPartitioningDestroy(&mpart);
1471:   }
1472:   PetscMalloc1(nloc,&is);
1473:   if (!foundpart) {

1475:     /* Partitioning by contiguous chunks of rows */

1477:     PetscInt mbs   = (rend-rstart)/bs;
1478:     PetscInt start = rstart;
1479:     for (i=0; i<nloc; i++) {
1480:       PetscInt count = (mbs/nloc + ((mbs % nloc) > i)) * bs;
1481:       ISCreateStride(PETSC_COMM_SELF,count,start,1,&is[i]);
1482:       start += count;
1483:     }

1485:   } else {

1487:     /* Partitioning by adjacency of diagonal block  */

1489:     const PetscInt *numbering;
1490:     PetscInt       *count,nidx,*indices,*newidx,start=0;
1491:     /* Get node count in each partition */
1492:     PetscMalloc1(nloc,&count);
1493:     ISPartitioningCount(ispart,nloc,count);
1494:     if (isbaij && bs > 1) { /* adjust for the block-aij case */
1495:       for (i=0; i<nloc; i++) count[i] *= bs;
1496:     }
1497:     /* Build indices from node numbering */
1498:     ISGetLocalSize(isnumb,&nidx);
1499:     PetscMalloc1(nidx,&indices);
1500:     for (i=0; i<nidx; i++) indices[i] = i; /* needs to be initialized */
1501:     ISGetIndices(isnumb,&numbering);
1502:     PetscSortIntWithPermutation(nidx,numbering,indices);
1503:     ISRestoreIndices(isnumb,&numbering);
1504:     if (isbaij && bs > 1) { /* adjust for the block-aij case */
1505:       PetscMalloc1(nidx*bs,&newidx);
1506:       for (i=0; i<nidx; i++) {
1507:         for (j=0; j<bs; j++) newidx[i*bs+j] = indices[i]*bs + j;
1508:       }
1509:       PetscFree(indices);
1510:       nidx   *= bs;
1511:       indices = newidx;
1512:     }
1513:     /* Shift to get global indices */
1514:     for (i=0; i<nidx; i++) indices[i] += rstart;

1516:     /* Build the index sets for each block */
1517:     for (i=0; i<nloc; i++) {
1518:       ISCreateGeneral(PETSC_COMM_SELF,count[i],&indices[start],PETSC_COPY_VALUES,&is[i]);
1519:       ISSort(is[i]);
1520:       start += count[i];
1521:     }

1523:     PetscFree(count);
1524:     PetscFree(indices);
1525:     ISDestroy(&isnumb);
1526:     ISDestroy(&ispart);
1527:   }
1528:   *iis = is;
1529:   return(0);
1530: }

1532: PETSC_INTERN PetscErrorCode  PCGASMCreateStraddlingSubdomains(Mat A,PetscInt N,PetscInt *n,IS *iis[])
1533: {
1534:   PetscErrorCode  ierr;

1537:   MatSubdomainsCreateCoalesce(A,N,n,iis);
1538:   return(0);
1539: }

1541: /*@C
1542:    PCGASMCreateSubdomains - Creates n index sets defining n nonoverlapping subdomains for the additive
1543:    Schwarz preconditioner for a any problem based on its matrix.

1545:    Collective

1547:    Input Parameters:
1548: +  A       - The global matrix operator
1549: -  N       - the number of global subdomains requested

1551:    Output Parameters:
1552: +  n   - the number of subdomains created on this processor
1553: -  iis - the array of index sets defining the local inner subdomains (on which the correction is applied)

1555:    Level: advanced

1557:    Note: When N >= A's communicator size, each subdomain is local -- contained within a single processor.
1558:          When N < size, the subdomains are 'straddling' (processor boundaries) and are no longer local.
1559:          The resulting subdomains can be use in PCGASMSetSubdomains(pc,n,iss,NULL).  The overlapping
1560:          outer subdomains will be automatically generated from these according to the requested amount of
1561:          overlap; this is currently supported only with local subdomains.

1563: .seealso: PCGASMSetSubdomains(), PCGASMDestroySubdomains()
1564: @*/
1565: PetscErrorCode  PCGASMCreateSubdomains(Mat A,PetscInt N,PetscInt *n,IS *iis[])
1566: {
1567:   PetscMPIInt     size;
1568:   PetscErrorCode  ierr;


1574:   if (N < 1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"Number of subdomains must be > 0, N = %D",N);
1575:   MPI_Comm_size(PetscObjectComm((PetscObject)A),&size);
1576:   if (N >= size) {
1577:     *n = N/size + (N%size);
1578:     PCGASMCreateLocalSubdomains(A,*n,iis);
1579:   } else {
1580:     PCGASMCreateStraddlingSubdomains(A,N,n,iis);
1581:   }
1582:   return(0);
1583: }

1585: /*@C
1586:    PCGASMDestroySubdomains - Destroys the index sets created with
1587:    PCGASMCreateSubdomains() or PCGASMCreateSubdomains2D. Should be
1588:    called after setting subdomains with PCGASMSetSubdomains().

1590:    Collective

1592:    Input Parameters:
1593: +  n   - the number of index sets
1594: .  iis - the array of inner subdomains,
1595: -  ois - the array of outer subdomains, can be NULL

1597:    Level: intermediate

1599:    Notes:
1600:     this is merely a convenience subroutine that walks each list,
1601:    destroys each IS on the list, and then frees the list. At the end the
1602:    list pointers are set to NULL.

1604: .seealso: PCGASMCreateSubdomains(), PCGASMSetSubdomains()
1605: @*/
1606: PetscErrorCode  PCGASMDestroySubdomains(PetscInt n,IS **iis,IS **ois)
1607: {
1608:   PetscInt       i;

1612:   if (n <= 0) return(0);
1613:   if (ois) {
1615:     if (*ois) {
1617:       for (i=0; i<n; i++) {
1618:         ISDestroy(&(*ois)[i]);
1619:       }
1620:       PetscFree((*ois));
1621:     }
1622:   }
1623:   if (iis) {
1625:     if (*iis) {
1627:       for (i=0; i<n; i++) {
1628:         ISDestroy(&(*iis)[i]);
1629:       }
1630:       PetscFree((*iis));
1631:     }
1632:   }
1633:   return(0);
1634: }

1636: #define PCGASMLocalSubdomainBounds2D(M,N,xleft,ylow,xright,yhigh,first,last,xleft_loc,ylow_loc,xright_loc,yhigh_loc,n) \
1637:   {                                                                                                       \
1638:     PetscInt first_row = first/M, last_row = last/M+1;                                                     \
1639:     /*                                                                                                    \
1640:      Compute ylow_loc and yhigh_loc so that (ylow_loc,xleft) and (yhigh_loc,xright) are the corners       \
1641:      of the bounding box of the intersection of the subdomain with the local ownership range (local       \
1642:      subdomain).                                                                                          \
1643:      Also compute xleft_loc and xright_loc as the lower and upper bounds on the first and last rows       \
1644:      of the intersection.                                                                                 \
1645:     */                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             \
1646:     /* ylow_loc is the grid row containing the first element of the local sumbdomain */                   \
1647:     *ylow_loc = PetscMax(first_row,ylow);                                                                    \
1648:     /* xleft_loc is the offset of first element of the local subdomain within its grid row (might actually be outside the local subdomain) */ \
1649:     *xleft_loc = *ylow_loc==first_row ? PetscMax(first%M,xleft) : xleft;                                                                            \
1650:     /* yhigh_loc is the grid row above the last local subdomain element */                                                                    \
1651:     *yhigh_loc = PetscMin(last_row,yhigh);                                                                                                     \
1652:     /* xright is the offset of the end of the  local subdomain within its grid row (might actually be outside the local subdomain) */         \
1653:     *xright_loc = *yhigh_loc==last_row ? PetscMin(xright,last%M) : xright;                                                                          \
1654:     /* Now compute the size of the local subdomain n. */ \
1655:     *n = 0;                                               \
1656:     if (*ylow_loc < *yhigh_loc) {                           \
1657:       PetscInt width = xright-xleft;                     \
1658:       *n += width*(*yhigh_loc-*ylow_loc-1);                 \
1659:       *n += PetscMin(PetscMax(*xright_loc-xleft,0),width); \
1660:       *n -= PetscMin(PetscMax(*xleft_loc-xleft,0), width); \
1661:     } \
1662:   }

1664: /*@
1665:    PCGASMCreateSubdomains2D - Creates the index sets for the overlapping Schwarz
1666:    preconditioner for a two-dimensional problem on a regular grid.

1668:    Collective

1670:    Input Parameters:
1671: +  pc       - the preconditioner context
1672: .  M        - the global number of grid points in the x direction
1673: .  N        - the global number of grid points in the y direction
1674: .  Mdomains - the global number of subdomains in the x direction
1675: .  Ndomains - the global number of subdomains in the y direction
1676: .  dof      - degrees of freedom per node
1677: -  overlap  - overlap in mesh lines

1679:    Output Parameters:
1680: +  Nsub - the number of local subdomains created
1681: .  iis  - array of index sets defining inner (nonoverlapping) subdomains
1682: -  ois  - array of index sets defining outer (overlapping, if overlap > 0) subdomains

1684:    Level: advanced

1686: .seealso: PCGASMSetSubdomains(), PCGASMGetSubKSP(), PCGASMSetOverlap()
1687: @*/
1688: PetscErrorCode  PCGASMCreateSubdomains2D(PC pc,PetscInt M,PetscInt N,PetscInt Mdomains,PetscInt Ndomains,PetscInt dof,PetscInt overlap,PetscInt *nsub,IS **iis,IS **ois)
1689: {
1691:   PetscMPIInt    size, rank;
1692:   PetscInt       i, j;
1693:   PetscInt       maxheight, maxwidth;
1694:   PetscInt       xstart, xleft, xright, xleft_loc, xright_loc;
1695:   PetscInt       ystart, ylow,  yhigh,  ylow_loc,  yhigh_loc;
1696:   PetscInt       x[2][2], y[2][2], n[2];
1697:   PetscInt       first, last;
1698:   PetscInt       nidx, *idx;
1699:   PetscInt       ii,jj,s,q,d;
1700:   PetscInt       k,kk;
1701:   PetscMPIInt    color;
1702:   MPI_Comm       comm, subcomm;
1703:   IS             **xis = NULL, **is = ois, **is_local = iis;

1706:   PetscObjectGetComm((PetscObject)pc, &comm);
1707:   MPI_Comm_size(comm, &size);
1708:   MPI_Comm_rank(comm, &rank);
1709:   MatGetOwnershipRange(pc->pmat, &first, &last);
1710:   if (first%dof || last%dof) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Matrix row partitioning unsuitable for domain decomposition: local row range (%D,%D) "
1711:                                       "does not respect the number of degrees of freedom per grid point %D", first, last, dof);

1713:   /* Determine the number of domains with nonzero intersections with the local ownership range. */
1714:   s      = 0;
1715:   ystart = 0;
1716:   for (j=0; j<Ndomains; ++j) {
1717:     maxheight = N/Ndomains + ((N % Ndomains) > j); /* Maximal height of subdomain */
1718:     if (maxheight < 2) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many %D subdomains in the vertical directon for mesh height %D", Ndomains, N);
1719:     /* Vertical domain limits with an overlap. */
1720:     ylow   = PetscMax(ystart - overlap,0);
1721:     yhigh  = PetscMin(ystart + maxheight + overlap,N);
1722:     xstart = 0;
1723:     for (i=0; i<Mdomains; ++i) {
1724:       maxwidth = M/Mdomains + ((M % Mdomains) > i); /* Maximal width of subdomain */
1725:       if (maxwidth < 2) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many %D subdomains in the horizontal direction for mesh width %D", Mdomains, M);
1726:       /* Horizontal domain limits with an overlap. */
1727:       xleft  = PetscMax(xstart - overlap,0);
1728:       xright = PetscMin(xstart + maxwidth + overlap,M);
1729:       /*
1730:          Determine whether this subdomain intersects this processor's ownership range of pc->pmat.
1731:       */
1732:       PCGASMLocalSubdomainBounds2D(M,N,xleft,ylow,xright,yhigh,first,last,(&xleft_loc),(&ylow_loc),(&xright_loc),(&yhigh_loc),(&nidx));
1733:       if (nidx) ++s;
1734:       xstart += maxwidth;
1735:     } /* for (i = 0; i < Mdomains; ++i) */
1736:     ystart += maxheight;
1737:   } /* for (j = 0; j < Ndomains; ++j) */

1739:   /* Now we can allocate the necessary number of ISs. */
1740:   *nsub  = s;
1741:   PetscMalloc1(*nsub,is);
1742:   PetscMalloc1(*nsub,is_local);
1743:   s      = 0;
1744:   ystart = 0;
1745:   for (j=0; j<Ndomains; ++j) {
1746:     maxheight = N/Ndomains + ((N % Ndomains) > j); /* Maximal height of subdomain */
1747:     if (maxheight < 2) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many %D subdomains in the vertical directon for mesh height %D", Ndomains, N);
1748:     /* Vertical domain limits with an overlap. */
1749:     y[0][0] = PetscMax(ystart - overlap,0);
1750:     y[0][1] = PetscMin(ystart + maxheight + overlap,N);
1751:     /* Vertical domain limits without an overlap. */
1752:     y[1][0] = ystart;
1753:     y[1][1] = PetscMin(ystart + maxheight,N);
1754:     xstart  = 0;
1755:     for (i=0; i<Mdomains; ++i) {
1756:       maxwidth = M/Mdomains + ((M % Mdomains) > i); /* Maximal width of subdomain */
1757:       if (maxwidth < 2) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many %D subdomains in the horizontal direction for mesh width %D", Mdomains, M);
1758:       /* Horizontal domain limits with an overlap. */
1759:       x[0][0] = PetscMax(xstart - overlap,0);
1760:       x[0][1] = PetscMin(xstart + maxwidth + overlap,M);
1761:       /* Horizontal domain limits without an overlap. */
1762:       x[1][0] = xstart;
1763:       x[1][1] = PetscMin(xstart+maxwidth,M);
1764:       /*
1765:          Determine whether this domain intersects this processor's ownership range of pc->pmat.
1766:          Do this twice: first for the domains with overlaps, and once without.
1767:          During the first pass create the subcommunicators, and use them on the second pass as well.
1768:       */
1769:       for (q = 0; q < 2; ++q) {
1770:         PetscBool split = PETSC_FALSE;
1771:         /*
1772:           domain limits, (xleft, xright) and (ylow, yheigh) are adjusted
1773:           according to whether the domain with an overlap or without is considered.
1774:         */
1775:         xleft = x[q][0]; xright = x[q][1];
1776:         ylow  = y[q][0]; yhigh  = y[q][1];
1777:         PCGASMLocalSubdomainBounds2D(M,N,xleft,ylow,xright,yhigh,first,last,(&xleft_loc),(&ylow_loc),(&xright_loc),(&yhigh_loc),(&nidx));
1778:         nidx *= dof;
1779:         n[q]  = nidx;
1780:         /*
1781:          Based on the counted number of indices in the local domain *with an overlap*,
1782:          construct a subcommunicator of all the processors supporting this domain.
1783:          Observe that a domain with an overlap might have nontrivial local support,
1784:          while the domain without an overlap might not.  Hence, the decision to participate
1785:          in the subcommunicator must be based on the domain with an overlap.
1786:          */
1787:         if (q == 0) {
1788:           if (nidx) color = 1;
1789:           else color = MPI_UNDEFINED;
1790:           MPI_Comm_split(comm, color, rank, &subcomm);
1791:           split = PETSC_TRUE;
1792:         }
1793:         /*
1794:          Proceed only if the number of local indices *with an overlap* is nonzero.
1795:          */
1796:         if (n[0]) {
1797:           if (q == 0) xis = is;
1798:           if (q == 1) {
1799:             /*
1800:              The IS for the no-overlap subdomain shares a communicator with the overlapping domain.
1801:              Moreover, if the overlap is zero, the two ISs are identical.
1802:              */
1803:             if (overlap == 0) {
1804:               (*is_local)[s] = (*is)[s];
1805:               PetscObjectReference((PetscObject)(*is)[s]);
1806:               continue;
1807:             } else {
1808:               xis     = is_local;
1809:               subcomm = ((PetscObject)(*is)[s])->comm;
1810:             }
1811:           } /* if (q == 1) */
1812:           idx  = NULL;
1813:           PetscMalloc1(nidx,&idx);
1814:           if (nidx) {
1815:             k = 0;
1816:             for (jj=ylow_loc; jj<yhigh_loc; ++jj) {
1817:               PetscInt x0 = (jj==ylow_loc) ? xleft_loc : xleft;
1818:               PetscInt x1 = (jj==yhigh_loc-1) ? xright_loc : xright;
1819:               kk = dof*(M*jj + x0);
1820:               for (ii=x0; ii<x1; ++ii) {
1821:                 for (d = 0; d < dof; ++d) {
1822:                   idx[k++] = kk++;
1823:                 }
1824:               }
1825:             }
1826:           }
1827:           ISCreateGeneral(subcomm,nidx,idx,PETSC_OWN_POINTER,(*xis)+s);
1828:           if (split) {
1829:             MPI_Comm_free(&subcomm);
1830:           }
1831:         }/* if (n[0]) */
1832:       }/* for (q = 0; q < 2; ++q) */
1833:       if (n[0]) ++s;
1834:       xstart += maxwidth;
1835:     } /* for (i = 0; i < Mdomains; ++i) */
1836:     ystart += maxheight;
1837:   } /* for (j = 0; j < Ndomains; ++j) */
1838:   return(0);
1839: }

1841: /*@C
1842:     PCGASMGetSubdomains - Gets the subdomains supported on this processor
1843:     for the additive Schwarz preconditioner.

1845:     Not Collective

1847:     Input Parameter:
1848: .   pc - the preconditioner context

1850:     Output Parameters:
1851: +   n   - the number of subdomains for this processor (default value = 1)
1852: .   iis - the index sets that define the inner subdomains (without overlap) supported on this processor (can be NULL)
1853: -   ois - the index sets that define the outer subdomains (with overlap) supported on this processor (can be NULL)

1855:     Notes:
1856:     The user is responsible for destroying the ISs and freeing the returned arrays.
1857:     The IS numbering is in the parallel, global numbering of the vector.

1859:     Level: advanced

1861: .seealso: PCGASMSetOverlap(), PCGASMGetSubKSP(), PCGASMCreateSubdomains2D(),
1862:           PCGASMSetSubdomains(), PCGASMGetSubmatrices()
1863: @*/
1864: PetscErrorCode  PCGASMGetSubdomains(PC pc,PetscInt *n,IS *iis[],IS *ois[])
1865: {
1866:   PC_GASM        *osm;
1868:   PetscBool      match;
1869:   PetscInt       i;

1873:   PetscObjectTypeCompare((PetscObject)pc,PCGASM,&match);
1874:   if (!match) SETERRQ2(PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONG, "Incorrect object type: expected %s, got %s instead", PCGASM, ((PetscObject)pc)->type_name);
1875:   osm = (PC_GASM*)pc->data;
1876:   if (n) *n = osm->n;
1877:   if (iis) {
1878:     PetscMalloc1(osm->n, iis);
1879:   }
1880:   if (ois) {
1881:     PetscMalloc1(osm->n, ois);
1882:   }
1883:   if (iis || ois) {
1884:     for (i = 0; i < osm->n; ++i) {
1885:       if (iis) (*iis)[i] = osm->iis[i];
1886:       if (ois) (*ois)[i] = osm->ois[i];
1887:     }
1888:   }
1889:   return(0);
1890: }

1892: /*@C
1893:     PCGASMGetSubmatrices - Gets the local submatrices (for this processor
1894:     only) for the additive Schwarz preconditioner.

1896:     Not Collective

1898:     Input Parameter:
1899: .   pc - the preconditioner context

1901:     Output Parameters:
1902: +   n   - the number of matrices for this processor (default value = 1)
1903: -   mat - the matrices

1905:     Notes:
1906:     matrices returned by this routine have the same communicators as the index sets (IS)
1907:            used to define subdomains in PCGASMSetSubdomains()
1908:     Level: advanced

1910: .seealso: PCGASMSetOverlap(), PCGASMGetSubKSP(),
1911:           PCGASMCreateSubdomains2D(), PCGASMSetSubdomains(), PCGASMGetSubdomains()
1912: @*/
1913: PetscErrorCode  PCGASMGetSubmatrices(PC pc,PetscInt *n,Mat *mat[])
1914: {
1915:   PC_GASM        *osm;
1917:   PetscBool      match;

1923:   if (!pc->setupcalled) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Must call after KSPSetUp() or PCSetUp().");
1924:   PetscObjectTypeCompare((PetscObject)pc,PCGASM,&match);
1925:   if (!match) SETERRQ2(PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONG, "Expected %s, got %s instead", PCGASM, ((PetscObject)pc)->type_name);
1926:   osm = (PC_GASM*)pc->data;
1927:   if (n) *n = osm->n;
1928:   if (mat) *mat = osm->pmat;
1929:   return(0);
1930: }

1932: /*@
1933:     PCGASMSetUseDMSubdomains - Indicates whether to use DMCreateDomainDecomposition() to define the subdomains, whenever possible.
1934:     Logically Collective

1936:     Input Parameters:
1937: +   pc  - the preconditioner
1938: -   flg - boolean indicating whether to use subdomains defined by the DM

1940:     Options Database Key:
1941: .   -pc_gasm_dm_subdomains -pc_gasm_overlap -pc_gasm_total_subdomains

1943:     Level: intermediate

1945:     Notes:
1946:     PCGASMSetSubdomains(), PCGASMSetTotalSubdomains() or PCGASMSetOverlap() take precedence over PCGASMSetUseDMSubdomains(),
1947:     so setting PCGASMSetSubdomains() with nontrivial subdomain ISs or any of PCGASMSetTotalSubdomains() and PCGASMSetOverlap()
1948:     automatically turns the latter off.

1950: .seealso: PCGASMGetUseDMSubdomains(), PCGASMSetSubdomains(), PCGASMSetOverlap()
1951:           PCGASMCreateSubdomains2D()
1952: @*/
1953: PetscErrorCode  PCGASMSetUseDMSubdomains(PC pc,PetscBool flg)
1954: {
1955:   PC_GASM        *osm = (PC_GASM*)pc->data;
1957:   PetscBool      match;

1962:   if (pc->setupcalled) SETERRQ(((PetscObject)pc)->comm,PETSC_ERR_ARG_WRONGSTATE,"Not for a setup PC.");
1963:   PetscObjectTypeCompare((PetscObject)pc,PCGASM,&match);
1964:   if (match) {
1965:     if (!osm->user_subdomains && osm->N == PETSC_DETERMINE && osm->overlap < 0) {
1966:       osm->dm_subdomains = flg;
1967:     }
1968:   }
1969:   return(0);
1970: }

1972: /*@
1973:     PCGASMGetUseDMSubdomains - Returns flag indicating whether to use DMCreateDomainDecomposition() to define the subdomains, whenever possible.
1974:     Not Collective

1976:     Input Parameter:
1977: .   pc  - the preconditioner

1979:     Output Parameter:
1980: .   flg - boolean indicating whether to use subdomains defined by the DM

1982:     Level: intermediate

1984: .seealso: PCGASMSetUseDMSubdomains(), PCGASMSetOverlap()
1985:           PCGASMCreateSubdomains2D()
1986: @*/
1987: PetscErrorCode  PCGASMGetUseDMSubdomains(PC pc,PetscBool* flg)
1988: {
1989:   PC_GASM        *osm = (PC_GASM*)pc->data;
1991:   PetscBool      match;

1996:   PetscObjectTypeCompare((PetscObject)pc,PCGASM,&match);
1997:   if (match) {
1998:     if (flg) *flg = osm->dm_subdomains;
1999:   }
2000:   return(0);
2001: }