Actual source code: asm.c

petsc-master 2020-11-24
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  1: /*
  2:   This file defines an additive Schwarz preconditioner for any Mat implementation.

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

  8:        n - total number of true subdomains on all processors
  9:        n_local_true - actual number of subdomains on this processor
 10:        n_local = maximum over all processors of n_local_true
 11: */

 13: #include <../src/ksp/pc/impls/asm/asm.h>

 15: static PetscErrorCode PCView_ASM(PC pc,PetscViewer viewer)
 16: {
 17:   PC_ASM         *osm = (PC_ASM*)pc->data;
 19:   PetscMPIInt    rank;
 20:   PetscInt       i,bsz;
 21:   PetscBool      iascii,isstring;
 22:   PetscViewer    sviewer;

 25:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERASCII,&iascii);
 26:   PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);
 27:   if (iascii) {
 28:     char overlaps[256] = "user-defined overlap",blocks[256] = "total subdomain blocks not yet set";
 29:     if (osm->overlap >= 0) {PetscSNPrintf(overlaps,sizeof(overlaps),"amount of overlap = %D",osm->overlap);}
 30:     if (osm->n > 0) {PetscSNPrintf(blocks,sizeof(blocks),"total subdomain blocks = %D",osm->n);}
 31:     PetscViewerASCIIPrintf(viewer,"  %s, %s\n",blocks,overlaps);
 32:     PetscViewerASCIIPrintf(viewer,"  restriction/interpolation type - %s\n",PCASMTypes[osm->type]);
 33:     if (osm->dm_subdomains) {PetscViewerASCIIPrintf(viewer,"  Additive Schwarz: using DM to define subdomains\n");}
 34:     if (osm->loctype != PC_COMPOSITE_ADDITIVE) {PetscViewerASCIIPrintf(viewer,"  Additive Schwarz: local solve composition type - %s\n",PCCompositeTypes[osm->loctype]);}
 35:     MPI_Comm_rank(PetscObjectComm((PetscObject)pc),&rank);
 36:     if (osm->same_local_solves) {
 37:       if (osm->ksp) {
 38:         PetscViewerASCIIPrintf(viewer,"  Local solver is the same for all blocks, as in the following KSP and PC objects on rank 0:\n");
 39:         PetscViewerGetSubViewer(viewer,PETSC_COMM_SELF,&sviewer);
 40:         if (!rank) {
 41:           PetscViewerASCIIPushTab(viewer);
 42:           KSPView(osm->ksp[0],sviewer);
 43:           PetscViewerASCIIPopTab(viewer);
 44:         }
 45:         PetscViewerRestoreSubViewer(viewer,PETSC_COMM_SELF,&sviewer);
 46:       }
 47:     } else {
 48:       PetscViewerASCIIPushSynchronized(viewer);
 49:       PetscViewerASCIISynchronizedPrintf(viewer,"  [%d] number of local blocks = %D\n",(int)rank,osm->n_local_true);
 50:       PetscViewerFlush(viewer);
 51:       PetscViewerASCIIPrintf(viewer,"  Local solve info for each block is in the following KSP and PC objects:\n");
 52:       PetscViewerASCIIPushTab(viewer);
 53:       PetscViewerASCIIPrintf(viewer,"- - - - - - - - - - - - - - - - - -\n");
 54:       PetscViewerGetSubViewer(viewer,PETSC_COMM_SELF,&sviewer);
 55:       for (i=0; i<osm->n_local_true; i++) {
 56:         ISGetLocalSize(osm->is[i],&bsz);
 57:         PetscViewerASCIISynchronizedPrintf(sviewer,"[%d] local block number %D, size = %D\n",(int)rank,i,bsz);
 58:         KSPView(osm->ksp[i],sviewer);
 59:         PetscViewerASCIISynchronizedPrintf(sviewer,"- - - - - - - - - - - - - - - - - -\n");
 60:       }
 61:       PetscViewerRestoreSubViewer(viewer,PETSC_COMM_SELF,&sviewer);
 62:       PetscViewerASCIIPopTab(viewer);
 63:       PetscViewerFlush(viewer);
 64:       PetscViewerASCIIPopSynchronized(viewer);
 65:     }
 66:   } else if (isstring) {
 67:     PetscViewerStringSPrintf(viewer," blocks=%D, overlap=%D, type=%s",osm->n,osm->overlap,PCASMTypes[osm->type]);
 68:     PetscViewerGetSubViewer(viewer,PETSC_COMM_SELF,&sviewer);
 69:     if (osm->ksp) {KSPView(osm->ksp[0],sviewer);}
 70:     PetscViewerRestoreSubViewer(viewer,PETSC_COMM_SELF,&sviewer);
 71:   }
 72:   return(0);
 73: }

 75: static PetscErrorCode PCASMPrintSubdomains(PC pc)
 76: {
 77:   PC_ASM         *osm = (PC_ASM*)pc->data;
 78:   const char     *prefix;
 79:   char           fname[PETSC_MAX_PATH_LEN+1];
 80:   PetscViewer    viewer, sviewer;
 81:   char           *s;
 82:   PetscInt       i,j,nidx;
 83:   const PetscInt *idx;
 84:   PetscMPIInt    rank, size;

 88:   MPI_Comm_size(PetscObjectComm((PetscObject)pc), &size);
 89:   MPI_Comm_rank(PetscObjectComm((PetscObject)pc), &rank);
 90:   PCGetOptionsPrefix(pc,&prefix);
 91:   PetscOptionsGetString(NULL,prefix,"-pc_asm_print_subdomains",fname,sizeof(fname),NULL);
 92:   if (fname[0] == 0) { PetscStrcpy(fname,"stdout"); };
 93:   PetscViewerASCIIOpen(PetscObjectComm((PetscObject)pc),fname,&viewer);
 94:   for (i=0; i<osm->n_local; i++) {
 95:     if (i < osm->n_local_true) {
 96:       ISGetLocalSize(osm->is[i],&nidx);
 97:       ISGetIndices(osm->is[i],&idx);
 98:       /* Print to a string viewer; no more than 15 characters per index plus 512 char for the header.*/
 99: #define len  16*(nidx+1)+512
100:       PetscMalloc1(len,&s);
101:       PetscViewerStringOpen(PETSC_COMM_SELF, s, len, &sviewer);
102: #undef len
103:       PetscViewerStringSPrintf(sviewer, "[%D:%D] Subdomain %D with overlap:\n", rank, size, i);
104:       for (j=0; j<nidx; j++) {
105:         PetscViewerStringSPrintf(sviewer,"%D ",idx[j]);
106:       }
107:       ISRestoreIndices(osm->is[i],&idx);
108:       PetscViewerStringSPrintf(sviewer,"\n");
109:       PetscViewerDestroy(&sviewer);
110:       PetscViewerASCIIPushSynchronized(viewer);
111:       PetscViewerASCIISynchronizedPrintf(viewer, s);
112:       PetscViewerFlush(viewer);
113:       PetscViewerASCIIPopSynchronized(viewer);
114:       PetscFree(s);
115:       if (osm->is_local) {
116:         /* Print to a string viewer; no more than 15 characters per index plus 512 char for the header.*/
117: #define len  16*(nidx+1)+512
118:         PetscMalloc1(len, &s);
119:         PetscViewerStringOpen(PETSC_COMM_SELF, s, len, &sviewer);
120: #undef len
121:         PetscViewerStringSPrintf(sviewer, "[%D:%D] Subdomain %D without overlap:\n", rank, size, i);
122:         ISGetLocalSize(osm->is_local[i],&nidx);
123:         ISGetIndices(osm->is_local[i],&idx);
124:         for (j=0; j<nidx; j++) {
125:           PetscViewerStringSPrintf(sviewer,"%D ",idx[j]);
126:         }
127:         ISRestoreIndices(osm->is_local[i],&idx);
128:         PetscViewerStringSPrintf(sviewer,"\n");
129:         PetscViewerDestroy(&sviewer);
130:         PetscViewerASCIIPushSynchronized(viewer);
131:         PetscViewerASCIISynchronizedPrintf(viewer, s);
132:         PetscViewerFlush(viewer);
133:         PetscViewerASCIIPopSynchronized(viewer);
134:         PetscFree(s);
135:       }
136:     } else {
137:       /* Participate in collective viewer calls. */
138:       PetscViewerASCIIPushSynchronized(viewer);
139:       PetscViewerFlush(viewer);
140:       PetscViewerASCIIPopSynchronized(viewer);
141:       /* Assume either all ranks have is_local or none do. */
142:       if (osm->is_local) {
143:         PetscViewerASCIIPushSynchronized(viewer);
144:         PetscViewerFlush(viewer);
145:         PetscViewerASCIIPopSynchronized(viewer);
146:       }
147:     }
148:   }
149:   PetscViewerFlush(viewer);
150:   PetscViewerDestroy(&viewer);
151:   return(0);
152: }

154: static PetscErrorCode PCSetUp_ASM(PC pc)
155: {
156:   PC_ASM         *osm = (PC_ASM*)pc->data;
158:   PetscBool      flg;
159:   PetscInt       i,m,m_local;
160:   MatReuse       scall = MAT_REUSE_MATRIX;
161:   IS             isl;
162:   KSP            ksp;
163:   PC             subpc;
164:   const char     *prefix,*pprefix;
165:   Vec            vec;
166:   DM             *domain_dm = NULL;

169:   if (!pc->setupcalled) {
170:     PetscInt m;

172:     /* Note: if subdomains have been set either via PCASMSetTotalSubdomains() or via PCASMSetLocalSubdomains(), osm->n_local_true will not be PETSC_DECIDE */
173:     if (osm->n_local_true == PETSC_DECIDE) {
174:       /* no subdomains given */
175:       /* try pc->dm first, if allowed */
176:       if (osm->dm_subdomains && pc->dm) {
177:         PetscInt  num_domains, d;
178:         char      **domain_names;
179:         IS        *inner_domain_is, *outer_domain_is;
180:         DMCreateDomainDecomposition(pc->dm, &num_domains, &domain_names, &inner_domain_is, &outer_domain_is, &domain_dm);
181:         osm->overlap = -1; /* We do not want to increase the overlap of the IS.
182:                               A future improvement of this code might allow one to use
183:                               DM-defined subdomains and also increase the overlap,
184:                               but that is not currently supported */
185:         if (num_domains) {
186:           PCASMSetLocalSubdomains(pc, num_domains, outer_domain_is, inner_domain_is);
187:         }
188:         for (d = 0; d < num_domains; ++d) {
189:           if (domain_names)    {PetscFree(domain_names[d]);}
190:           if (inner_domain_is) {ISDestroy(&inner_domain_is[d]);}
191:           if (outer_domain_is) {ISDestroy(&outer_domain_is[d]);}
192:         }
193:         PetscFree(domain_names);
194:         PetscFree(inner_domain_is);
195:         PetscFree(outer_domain_is);
196:       }
197:       if (osm->n_local_true == PETSC_DECIDE) {
198:         /* still no subdomains; use one subdomain per processor */
199:         osm->n_local_true = 1;
200:       }
201:     }
202:     { /* determine the global and max number of subdomains */
203:       struct {PetscInt max,sum;} inwork,outwork;
204:       PetscMPIInt size;

206:       inwork.max   = osm->n_local_true;
207:       inwork.sum   = osm->n_local_true;
208:       MPIU_Allreduce(&inwork,&outwork,1,MPIU_2INT,MPIU_MAXSUM_OP,PetscObjectComm((PetscObject)pc));
209:       osm->n_local = outwork.max;
210:       osm->n       = outwork.sum;

212:       MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
213:       if (outwork.max == 1 && outwork.sum == size) {
214:         /* osm->n_local_true = 1 on all processes, set this option may enable use of optimized MatCreateSubMatrices() implementation */
215:         MatSetOption(pc->pmat,MAT_SUBMAT_SINGLEIS,PETSC_TRUE);
216:       }
217:     }
218:     if (!osm->is) { /* create the index sets */
219:       PCASMCreateSubdomains(pc->pmat,osm->n_local_true,&osm->is);
220:     }
221:     if (osm->n_local_true > 1 && !osm->is_local) {
222:       PetscMalloc1(osm->n_local_true,&osm->is_local);
223:       for (i=0; i<osm->n_local_true; i++) {
224:         if (osm->overlap > 0) { /* With positive overlap, osm->is[i] will be modified */
225:           ISDuplicate(osm->is[i],&osm->is_local[i]);
226:           ISCopy(osm->is[i],osm->is_local[i]);
227:         } else {
228:           PetscObjectReference((PetscObject)osm->is[i]);
229:           osm->is_local[i] = osm->is[i];
230:         }
231:       }
232:     }
233:     PCGetOptionsPrefix(pc,&prefix);
234:     flg  = PETSC_FALSE;
235:     PetscOptionsGetBool(NULL,prefix,"-pc_asm_print_subdomains",&flg,NULL);
236:     if (flg) { PCASMPrintSubdomains(pc); }

238:     if (osm->overlap > 0) {
239:       /* Extend the "overlapping" regions by a number of steps */
240:       MatIncreaseOverlap(pc->pmat,osm->n_local_true,osm->is,osm->overlap);
241:     }
242:     if (osm->sort_indices) {
243:       for (i=0; i<osm->n_local_true; i++) {
244:         ISSort(osm->is[i]);
245:         if (osm->is_local) {
246:           ISSort(osm->is_local[i]);
247:         }
248:       }
249:     }

251:     if (!osm->ksp) {
252:       /* Create the local solvers */
253:       PetscMalloc1(osm->n_local_true,&osm->ksp);
254:       if (domain_dm) {
255:         PetscInfo(pc,"Setting up ASM subproblems using the embedded DM\n");
256:       }
257:       for (i=0; i<osm->n_local_true; i++) {
258:         KSPCreate(PETSC_COMM_SELF,&ksp);
259:         KSPSetErrorIfNotConverged(ksp,pc->erroriffailure);
260:         PetscLogObjectParent((PetscObject)pc,(PetscObject)ksp);
261:         PetscObjectIncrementTabLevel((PetscObject)ksp,(PetscObject)pc,1);
262:         KSPSetType(ksp,KSPPREONLY);
263:         KSPGetPC(ksp,&subpc);
264:         PCGetOptionsPrefix(pc,&prefix);
265:         KSPSetOptionsPrefix(ksp,prefix);
266:         KSPAppendOptionsPrefix(ksp,"sub_");
267:         if (domain_dm) {
268:           KSPSetDM(ksp, domain_dm[i]);
269:           KSPSetDMActive(ksp, PETSC_FALSE);
270:           DMDestroy(&domain_dm[i]);
271:         }
272:         osm->ksp[i] = ksp;
273:       }
274:       if (domain_dm) {
275:         PetscFree(domain_dm);
276:       }
277:     }

279:     ISConcatenate(PETSC_COMM_SELF, osm->n_local_true, osm->is, &osm->lis);
280:     ISSortRemoveDups(osm->lis);
281:     ISGetLocalSize(osm->lis, &m);

283:     scall = MAT_INITIAL_MATRIX;
284:   } else {
285:     /*
286:        Destroy the blocks from the previous iteration
287:     */
288:     if (pc->flag == DIFFERENT_NONZERO_PATTERN) {
289:       MatDestroyMatrices(osm->n_local_true,&osm->pmat);
290:       scall = MAT_INITIAL_MATRIX;
291:     }
292:   }

294:   /*
295:      Extract out the submatrices
296:   */
297:   MatCreateSubMatrices(pc->pmat,osm->n_local_true,osm->is,osm->is,scall,&osm->pmat);
298:   if (scall == MAT_INITIAL_MATRIX) {
299:     PetscObjectGetOptionsPrefix((PetscObject)pc->pmat,&pprefix);
300:     for (i=0; i<osm->n_local_true; i++) {
301:       PetscLogObjectParent((PetscObject)pc,(PetscObject)osm->pmat[i]);
302:       PetscObjectSetOptionsPrefix((PetscObject)osm->pmat[i],pprefix);
303:     }
304:   }

306:   /* Convert the types of the submatrices (if needbe) */
307:   if (osm->sub_mat_type) {
308:     for (i=0; i<osm->n_local_true; i++) {
309:       MatConvert(osm->pmat[i],osm->sub_mat_type,MAT_INPLACE_MATRIX,&(osm->pmat[i]));
310:     }
311:   }

313:   if (!pc->setupcalled) {
314:     VecType vtype;

316:     /* Create the local work vectors (from the local matrices) and scatter contexts */
317:     MatCreateVecs(pc->pmat,&vec,NULL);

319:     if (osm->is_local && (osm->type == PC_ASM_INTERPOLATE || osm->type == PC_ASM_NONE)) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Cannot use interpolate or none PCASMType if is_local was provided to PCASMSetLocalSubdomains()");
320:     if (osm->is_local && osm->type == PC_ASM_RESTRICT && osm->loctype == PC_COMPOSITE_ADDITIVE) {
321:       PetscMalloc1(osm->n_local_true,&osm->lprolongation);
322:     }
323:     PetscMalloc1(osm->n_local_true,&osm->lrestriction);
324:     PetscMalloc1(osm->n_local_true,&osm->x);
325:     PetscMalloc1(osm->n_local_true,&osm->y);

327:     ISGetLocalSize(osm->lis,&m);
328:     ISCreateStride(PETSC_COMM_SELF,m,0,1,&isl);
329:     MatGetVecType(osm->pmat[0],&vtype);
330:     VecCreate(PETSC_COMM_SELF,&osm->lx);
331:     VecSetSizes(osm->lx,m,m);
332:     VecSetType(osm->lx,vtype);
333:     VecDuplicate(osm->lx, &osm->ly);
334:     VecScatterCreate(vec,osm->lis,osm->lx,isl,&osm->restriction);
335:     ISDestroy(&isl);

337:     for (i=0; i<osm->n_local_true; ++i) {
338:       ISLocalToGlobalMapping ltog;
339:       IS                     isll;
340:       const PetscInt         *idx_is;
341:       PetscInt               *idx_lis,nout;

343:       ISGetLocalSize(osm->is[i],&m);
344:       MatCreateVecs(osm->pmat[i],&osm->x[i],NULL);
345:       VecDuplicate(osm->x[i],&osm->y[i]);

347:       /* generate a scatter from ly to y[i] picking all the overlapping is[i] entries */
348:       ISLocalToGlobalMappingCreateIS(osm->lis,&ltog);
349:       ISGetLocalSize(osm->is[i],&m);
350:       ISGetIndices(osm->is[i], &idx_is);
351:       PetscMalloc1(m,&idx_lis);
352:       ISGlobalToLocalMappingApply(ltog,IS_GTOLM_DROP,m,idx_is,&nout,idx_lis);
353:       if (nout != m) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"is not a subset of lis");
354:       ISRestoreIndices(osm->is[i], &idx_is);
355:       ISCreateGeneral(PETSC_COMM_SELF,m,idx_lis,PETSC_OWN_POINTER,&isll);
356:       ISLocalToGlobalMappingDestroy(&ltog);
357:       ISCreateStride(PETSC_COMM_SELF,m,0,1,&isl);
358:       VecScatterCreate(osm->ly,isll,osm->y[i],isl,&osm->lrestriction[i]);
359:       ISDestroy(&isll);
360:       ISDestroy(&isl);
361:       if (osm->lprolongation) { /* generate a scatter from y[i] to ly picking only the the non-overlapping is_local[i] entries */
362:         ISLocalToGlobalMapping ltog;
363:         IS                     isll,isll_local;
364:         const PetscInt         *idx_local;
365:         PetscInt               *idx1, *idx2, nout;

367:         ISGetLocalSize(osm->is_local[i],&m_local);
368:         ISGetIndices(osm->is_local[i], &idx_local);

370:         ISLocalToGlobalMappingCreateIS(osm->is[i],&ltog);
371:         PetscMalloc1(m_local,&idx1);
372:         ISGlobalToLocalMappingApply(ltog,IS_GTOLM_DROP,m_local,idx_local,&nout,idx1);
373:         ISLocalToGlobalMappingDestroy(&ltog);
374:         if (nout != m_local) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"is_local not a subset of is");
375:         ISCreateGeneral(PETSC_COMM_SELF,m_local,idx1,PETSC_OWN_POINTER,&isll);

377:         ISLocalToGlobalMappingCreateIS(osm->lis,&ltog);
378:         PetscMalloc1(m_local,&idx2);
379:         ISGlobalToLocalMappingApply(ltog,IS_GTOLM_DROP,m_local,idx_local,&nout,idx2);
380:         ISLocalToGlobalMappingDestroy(&ltog);
381:         if (nout != m_local) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"is_local not a subset of lis");
382:         ISCreateGeneral(PETSC_COMM_SELF,m_local,idx2,PETSC_OWN_POINTER,&isll_local);

384:         ISRestoreIndices(osm->is_local[i], &idx_local);
385:         VecScatterCreate(osm->y[i],isll,osm->ly,isll_local,&osm->lprolongation[i]);

387:         ISDestroy(&isll);
388:         ISDestroy(&isll_local);
389:       }
390:     }
391:     VecDestroy(&vec);
392:   }

394:   if (osm->loctype == PC_COMPOSITE_MULTIPLICATIVE) {
395:     IS      *cis;
396:     PetscInt c;

398:     PetscMalloc1(osm->n_local_true, &cis);
399:     for (c = 0; c < osm->n_local_true; ++c) cis[c] = osm->lis;
400:     MatCreateSubMatrices(pc->pmat, osm->n_local_true, osm->is, cis, scall, &osm->lmats);
401:     PetscFree(cis);
402:   }

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

408:   /*
409:      Loop over subdomains putting them into local ksp
410:   */
411:   for (i=0; i<osm->n_local_true; i++) {
412:     KSPSetOperators(osm->ksp[i],osm->pmat[i],osm->pmat[i]);
413:     if (!pc->setupcalled) {
414:       KSPSetFromOptions(osm->ksp[i]);
415:     }
416:   }
417:   return(0);
418: }

420: static PetscErrorCode PCSetUpOnBlocks_ASM(PC pc)
421: {
422:   PC_ASM             *osm = (PC_ASM*)pc->data;
423:   PetscErrorCode     ierr;
424:   PetscInt           i;
425:   KSPConvergedReason reason;

428:   for (i=0; i<osm->n_local_true; i++) {
429:     KSPSetUp(osm->ksp[i]);
430:     KSPGetConvergedReason(osm->ksp[i],&reason);
431:     if (reason == KSP_DIVERGED_PC_FAILED) {
432:       pc->failedreason = PC_SUBPC_ERROR;
433:     }
434:   }
435:   return(0);
436: }

438: static PetscErrorCode PCApply_ASM(PC pc,Vec x,Vec y)
439: {
440:   PC_ASM         *osm = (PC_ASM*)pc->data;
442:   PetscInt       i,n_local_true = osm->n_local_true;
443:   ScatterMode    forward = SCATTER_FORWARD,reverse = SCATTER_REVERSE;

446:   /*
447:      support for limiting the restriction or interpolation to only local
448:      subdomain values (leaving the other values 0).
449:   */
450:   if (!(osm->type & PC_ASM_RESTRICT)) {
451:     forward = SCATTER_FORWARD_LOCAL;
452:     /* have to zero the work RHS since scatter may leave some slots empty */
453:     VecSet(osm->lx, 0.0);
454:   }
455:   if (!(osm->type & PC_ASM_INTERPOLATE)) {
456:     reverse = SCATTER_REVERSE_LOCAL;
457:   }

459:   if (osm->loctype == PC_COMPOSITE_MULTIPLICATIVE || osm->loctype == PC_COMPOSITE_ADDITIVE) {
460:     /* zero the global and the local solutions */
461:     VecSet(y, 0.0);
462:     VecSet(osm->ly, 0.0);

464:     /* copy the global RHS to local RHS including the ghost nodes */
465:     VecScatterBegin(osm->restriction, x, osm->lx, INSERT_VALUES, forward);
466:     VecScatterEnd(osm->restriction, x, osm->lx, INSERT_VALUES, forward);

468:     /* restrict local RHS to the overlapping 0-block RHS */
469:     VecScatterBegin(osm->lrestriction[0], osm->lx, osm->x[0], INSERT_VALUES, forward);
470:     VecScatterEnd(osm->lrestriction[0], osm->lx, osm->x[0], INSERT_VALUES, forward);

472:     /* do the local solves */
473:     for (i = 0; i < n_local_true; ++i) {

475:       /* solve the overlapping i-block */
476:       PetscLogEventBegin(PC_ApplyOnBlocks, osm->ksp[i], osm->x[i], osm->y[i],0);
477:       KSPSolve(osm->ksp[i], osm->x[i], osm->y[i]);
478:       KSPCheckSolve(osm->ksp[i], pc, osm->y[i]);
479:       PetscLogEventEnd(PC_ApplyOnBlocks, osm->ksp[i], osm->x[i], osm->y[i], 0);

481:       if (osm->lprolongation) { /* interpolate the non-overlapping i-block solution to the local solution (only for restrictive additive) */
482:         VecScatterBegin(osm->lprolongation[i], osm->y[i], osm->ly, ADD_VALUES, forward);
483:         VecScatterEnd(osm->lprolongation[i], osm->y[i], osm->ly, ADD_VALUES, forward);
484:       } else { /* interpolate the overlapping i-block solution to the local solution */
485:         VecScatterBegin(osm->lrestriction[i], osm->y[i], osm->ly, ADD_VALUES, reverse);
486:         VecScatterEnd(osm->lrestriction[i], osm->y[i], osm->ly, ADD_VALUES, reverse);
487:       }

489:       if (i < n_local_true-1) {
490:         /* restrict local RHS to the overlapping (i+1)-block RHS */
491:         VecScatterBegin(osm->lrestriction[i+1], osm->lx, osm->x[i+1], INSERT_VALUES, forward);
492:         VecScatterEnd(osm->lrestriction[i+1], osm->lx, osm->x[i+1], INSERT_VALUES, forward);

494:         if (osm->loctype == PC_COMPOSITE_MULTIPLICATIVE) {
495:           /* update the overlapping (i+1)-block RHS using the current local solution */
496:           MatMult(osm->lmats[i+1], osm->ly, osm->y[i+1]);
497:           VecAXPBY(osm->x[i+1],-1.,1., osm->y[i+1]);
498:         }
499:       }
500:     }
501:     /* add the local solution to the global solution including the ghost nodes */
502:     VecScatterBegin(osm->restriction, osm->ly, y, ADD_VALUES, reverse);
503:     VecScatterEnd(osm->restriction, osm->ly, y, ADD_VALUES, reverse);
504:   } else SETERRQ1(PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONG, "Invalid local composition type: %s", PCCompositeTypes[osm->loctype]);
505:   return(0);
506: }

508: static PetscErrorCode PCMatApply_ASM(PC pc,Mat X,Mat Y)
509: {
510:   PC_ASM         *osm = (PC_ASM*)pc->data;
511:   Mat            Z,W;
512:   Vec            x;
513:   PetscInt       i,m,N;
514:   ScatterMode    forward = SCATTER_FORWARD,reverse = SCATTER_REVERSE;

518:   if (osm->n_local_true > 1) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Not yet implemented");
519:   /*
520:      support for limiting the restriction or interpolation to only local
521:      subdomain values (leaving the other values 0).
522:   */
523:   if (!(osm->type & PC_ASM_RESTRICT)) {
524:     forward = SCATTER_FORWARD_LOCAL;
525:     /* have to zero the work RHS since scatter may leave some slots empty */
526:     VecSet(osm->lx, 0.0);
527:   }
528:   if (!(osm->type & PC_ASM_INTERPOLATE)) {
529:     reverse = SCATTER_REVERSE_LOCAL;
530:   }
531:   VecGetLocalSize(osm->x[0], &m);
532:   MatGetSize(X, NULL, &N);
533:   MatCreateSeqDense(PETSC_COMM_SELF, m, N, NULL, &Z);
534:   if (osm->loctype == PC_COMPOSITE_MULTIPLICATIVE || osm->loctype == PC_COMPOSITE_ADDITIVE) {
535:     /* zero the global and the local solutions */
536:     MatZeroEntries(Y);
537:     VecSet(osm->ly, 0.0);

539:     for (i = 0; i < N; ++i) {
540:       MatDenseGetColumnVecRead(X, i, &x);
541:       /* copy the global RHS to local RHS including the ghost nodes */
542:       VecScatterBegin(osm->restriction, x, osm->lx, INSERT_VALUES, forward);
543:       VecScatterEnd(osm->restriction, x, osm->lx, INSERT_VALUES, forward);
544:       MatDenseRestoreColumnVecRead(X, i, &x);

546:       MatDenseGetColumnVecWrite(Z, i, &x);
547:       /* restrict local RHS to the overlapping 0-block RHS */
548:       VecScatterBegin(osm->lrestriction[0], osm->lx, x, INSERT_VALUES, forward);
549:       VecScatterEnd(osm->lrestriction[0], osm->lx, x, INSERT_VALUES, forward);
550:       MatDenseRestoreColumnVecWrite(Z, i, &x);
551:     }
552:     MatCreateSeqDense(PETSC_COMM_SELF, m, N, NULL, &W);
553:     /* solve the overlapping 0-block */
554:     PetscLogEventBegin(PC_ApplyOnBlocks, osm->ksp[0], Z, W, 0);
555:     KSPMatSolve(osm->ksp[0], Z, W);
556:     KSPCheckSolve(osm->ksp[0], pc, NULL);
557:     PetscLogEventEnd(PC_ApplyOnBlocks, osm->ksp[0], Z, W,0);
558:     MatDestroy(&Z);

560:     for (i = 0; i < N; ++i) {
561:       VecSet(osm->ly, 0.0);
562:       MatDenseGetColumnVecRead(W, i, &x);
563:       if (osm->lprolongation) { /* interpolate the non-overlapping 0-block solution to the local solution (only for restrictive additive) */
564:         VecScatterBegin(osm->lprolongation[0], x, osm->ly, ADD_VALUES, forward);
565:         VecScatterEnd(osm->lprolongation[0], x, osm->ly, ADD_VALUES, forward);
566:       } else { /* interpolate the overlapping 0-block solution to the local solution */
567:         VecScatterBegin(osm->lrestriction[0], x, osm->ly, ADD_VALUES, reverse);
568:         VecScatterEnd(osm->lrestriction[0], x, osm->ly, ADD_VALUES, reverse);
569:       }
570:       MatDenseRestoreColumnVecRead(W, i, &x);

572:       MatDenseGetColumnVecWrite(Y, i, &x);
573:       /* add the local solution to the global solution including the ghost nodes */
574:       VecScatterBegin(osm->restriction, osm->ly, x, ADD_VALUES, reverse);
575:       VecScatterEnd(osm->restriction, osm->ly, x, ADD_VALUES, reverse);
576:       MatDenseRestoreColumnVecWrite(Y, i, &x);
577:     }
578:     MatDestroy(&W);
579:   } else SETERRQ1(PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONG, "Invalid local composition type: %s", PCCompositeTypes[osm->loctype]);
580:   return(0);
581: }

583: static PetscErrorCode PCApplyTranspose_ASM(PC pc,Vec x,Vec y)
584: {
585:   PC_ASM         *osm = (PC_ASM*)pc->data;
587:   PetscInt       i,n_local_true = osm->n_local_true;
588:   ScatterMode    forward = SCATTER_FORWARD,reverse = SCATTER_REVERSE;

591:   /*
592:      Support for limiting the restriction or interpolation to only local
593:      subdomain values (leaving the other values 0).

595:      Note: these are reversed from the PCApply_ASM() because we are applying the
596:      transpose of the three terms
597:   */

599:   if (!(osm->type & PC_ASM_INTERPOLATE)) {
600:     forward = SCATTER_FORWARD_LOCAL;
601:     /* have to zero the work RHS since scatter may leave some slots empty */
602:     VecSet(osm->lx, 0.0);
603:   }
604:   if (!(osm->type & PC_ASM_RESTRICT)) reverse = SCATTER_REVERSE_LOCAL;

606:   /* zero the global and the local solutions */
607:   VecSet(y, 0.0);
608:   VecSet(osm->ly, 0.0);

610:   /* Copy the global RHS to local RHS including the ghost nodes */
611:   VecScatterBegin(osm->restriction, x, osm->lx, INSERT_VALUES, forward);
612:   VecScatterEnd(osm->restriction, x, osm->lx, INSERT_VALUES, forward);

614:   /* Restrict local RHS to the overlapping 0-block RHS */
615:   VecScatterBegin(osm->lrestriction[0], osm->lx, osm->x[0], INSERT_VALUES, forward);
616:   VecScatterEnd(osm->lrestriction[0], osm->lx, osm->x[0], INSERT_VALUES, forward);

618:   /* do the local solves */
619:   for (i = 0; i < n_local_true; ++i) {

621:     /* solve the overlapping i-block */
622:     PetscLogEventBegin(PC_ApplyOnBlocks,osm->ksp[i],osm->x[i],osm->y[i],0);
623:     KSPSolveTranspose(osm->ksp[i], osm->x[i], osm->y[i]);
624:     KSPCheckSolve(osm->ksp[i],pc,osm->y[i]);
625:     PetscLogEventEnd(PC_ApplyOnBlocks,osm->ksp[i],osm->x[i],osm->y[i],0);

627:     if (osm->lprolongation) { /* interpolate the non-overlapping i-block solution to the local solution */
628:       VecScatterBegin(osm->lprolongation[i], osm->y[i], osm->ly, ADD_VALUES, forward);
629:       VecScatterEnd(osm->lprolongation[i], osm->y[i], osm->ly, ADD_VALUES, forward);
630:     } else { /* interpolate the overlapping i-block solution to the local solution */
631:       VecScatterBegin(osm->lrestriction[i], osm->y[i], osm->ly, ADD_VALUES, reverse);
632:       VecScatterEnd(osm->lrestriction[i], osm->y[i], osm->ly, ADD_VALUES, reverse);
633:     }

635:     if (i < n_local_true-1) {
636:       /* Restrict local RHS to the overlapping (i+1)-block RHS */
637:       VecScatterBegin(osm->lrestriction[i+1], osm->lx, osm->x[i+1], INSERT_VALUES, forward);
638:       VecScatterEnd(osm->lrestriction[i+1], osm->lx, osm->x[i+1], INSERT_VALUES, forward);
639:     }
640:   }
641:   /* Add the local solution to the global solution including the ghost nodes */
642:   VecScatterBegin(osm->restriction, osm->ly, y, ADD_VALUES, reverse);
643:   VecScatterEnd(osm->restriction, osm->ly, y, ADD_VALUES, reverse);

645:   return(0);

647: }

649: static PetscErrorCode PCReset_ASM(PC pc)
650: {
651:   PC_ASM         *osm = (PC_ASM*)pc->data;
653:   PetscInt       i;

656:   if (osm->ksp) {
657:     for (i=0; i<osm->n_local_true; i++) {
658:       KSPReset(osm->ksp[i]);
659:     }
660:   }
661:   if (osm->pmat) {
662:     if (osm->n_local_true > 0) {
663:       MatDestroySubMatrices(osm->n_local_true,&osm->pmat);
664:     }
665:   }
666:   if (osm->lrestriction) {
667:     VecScatterDestroy(&osm->restriction);
668:     for (i=0; i<osm->n_local_true; i++) {
669:       VecScatterDestroy(&osm->lrestriction[i]);
670:       if (osm->lprolongation) {VecScatterDestroy(&osm->lprolongation[i]);}
671:       VecDestroy(&osm->x[i]);
672:       VecDestroy(&osm->y[i]);
673:     }
674:     PetscFree(osm->lrestriction);
675:     if (osm->lprolongation) {PetscFree(osm->lprolongation);}
676:     PetscFree(osm->x);
677:     PetscFree(osm->y);

679:   }
680:   PCASMDestroySubdomains(osm->n_local_true,osm->is,osm->is_local);
681:   ISDestroy(&osm->lis);
682:   VecDestroy(&osm->lx);
683:   VecDestroy(&osm->ly);
684:   if (osm->loctype == PC_COMPOSITE_MULTIPLICATIVE) {
685:     MatDestroyMatrices(osm->n_local_true, &osm->lmats);
686:   }

688:   PetscFree(osm->sub_mat_type);

690:   osm->is       = NULL;
691:   osm->is_local = NULL;
692:   return(0);
693: }

695: static PetscErrorCode PCDestroy_ASM(PC pc)
696: {
697:   PC_ASM         *osm = (PC_ASM*)pc->data;
699:   PetscInt       i;

702:   PCReset_ASM(pc);
703:   if (osm->ksp) {
704:     for (i=0; i<osm->n_local_true; i++) {
705:       KSPDestroy(&osm->ksp[i]);
706:     }
707:     PetscFree(osm->ksp);
708:   }
709:   PetscFree(pc->data);
710:   return(0);
711: }

713: static PetscErrorCode PCSetFromOptions_ASM(PetscOptionItems *PetscOptionsObject,PC pc)
714: {
715:   PC_ASM         *osm = (PC_ASM*)pc->data;
717:   PetscInt       blocks,ovl;
718:   PetscBool      flg;
719:   PCASMType      asmtype;
720:   PCCompositeType loctype;
721:   char           sub_mat_type[256];

724:   PetscOptionsHead(PetscOptionsObject,"Additive Schwarz options");
725:   PetscOptionsBool("-pc_asm_dm_subdomains","Use DMCreateDomainDecomposition() to define subdomains","PCASMSetDMSubdomains",osm->dm_subdomains,&osm->dm_subdomains,&flg);
726:   PetscOptionsInt("-pc_asm_blocks","Number of subdomains","PCASMSetTotalSubdomains",osm->n,&blocks,&flg);
727:   if (flg) {
728:     PCASMSetTotalSubdomains(pc,blocks,NULL,NULL);
729:     osm->dm_subdomains = PETSC_FALSE;
730:   }
731:   PetscOptionsInt("-pc_asm_local_blocks","Number of local subdomains","PCASMSetLocalSubdomains",osm->n_local_true,&blocks,&flg);
732:   if (flg) {
733:     PCASMSetLocalSubdomains(pc,blocks,NULL,NULL);
734:     osm->dm_subdomains = PETSC_FALSE;
735:   }
736:   PetscOptionsInt("-pc_asm_overlap","Number of grid points overlap","PCASMSetOverlap",osm->overlap,&ovl,&flg);
737:   if (flg) {
738:     PCASMSetOverlap(pc,ovl);
739:     osm->dm_subdomains = PETSC_FALSE;
740:   }
741:   flg  = PETSC_FALSE;
742:   PetscOptionsEnum("-pc_asm_type","Type of restriction/extension","PCASMSetType",PCASMTypes,(PetscEnum)osm->type,(PetscEnum*)&asmtype,&flg);
743:   if (flg) {PCASMSetType(pc,asmtype); }
744:   flg  = PETSC_FALSE;
745:   PetscOptionsEnum("-pc_asm_local_type","Type of local solver composition","PCASMSetLocalType",PCCompositeTypes,(PetscEnum)osm->loctype,(PetscEnum*)&loctype,&flg);
746:   if (flg) {PCASMSetLocalType(pc,loctype); }
747:   PetscOptionsFList("-pc_asm_sub_mat_type","Subsolve Matrix Type","PCASMSetSubMatType",MatList,NULL,sub_mat_type,256,&flg);
748:   if (flg) {
749:     PCASMSetSubMatType(pc,sub_mat_type);
750:   }
751:   PetscOptionsTail();
752:   return(0);
753: }

755: /*------------------------------------------------------------------------------------*/

757: static PetscErrorCode  PCASMSetLocalSubdomains_ASM(PC pc,PetscInt n,IS is[],IS is_local[])
758: {
759:   PC_ASM         *osm = (PC_ASM*)pc->data;
761:   PetscInt       i;

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

767:   if (!pc->setupcalled) {
768:     if (is) {
769:       for (i=0; i<n; i++) {PetscObjectReference((PetscObject)is[i]);}
770:     }
771:     if (is_local) {
772:       for (i=0; i<n; i++) {PetscObjectReference((PetscObject)is_local[i]);}
773:     }
774:     PCASMDestroySubdomains(osm->n_local_true,osm->is,osm->is_local);

776:     osm->n_local_true = n;
777:     osm->is           = NULL;
778:     osm->is_local     = NULL;
779:     if (is) {
780:       PetscMalloc1(n,&osm->is);
781:       for (i=0; i<n; i++) osm->is[i] = is[i];
782:       /* Flag indicating that the user has set overlapping subdomains so PCASM should not increase their size. */
783:       osm->overlap = -1;
784:     }
785:     if (is_local) {
786:       PetscMalloc1(n,&osm->is_local);
787:       for (i=0; i<n; i++) osm->is_local[i] = is_local[i];
788:       if (!is) {
789:         PetscMalloc1(osm->n_local_true,&osm->is);
790:         for (i=0; i<osm->n_local_true; i++) {
791:           if (osm->overlap > 0) { /* With positive overlap, osm->is[i] will be modified */
792:             ISDuplicate(osm->is_local[i],&osm->is[i]);
793:             ISCopy(osm->is_local[i],osm->is[i]);
794:           } else {
795:             PetscObjectReference((PetscObject)osm->is_local[i]);
796:             osm->is[i] = osm->is_local[i];
797:           }
798:         }
799:       }
800:     }
801:   }
802:   return(0);
803: }

805: static PetscErrorCode  PCASMSetTotalSubdomains_ASM(PC pc,PetscInt N,IS *is,IS *is_local)
806: {
807:   PC_ASM         *osm = (PC_ASM*)pc->data;
809:   PetscMPIInt    rank,size;
810:   PetscInt       n;

813:   if (N < 1) SETERRQ1(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_OUTOFRANGE,"Number of total blocks must be > 0, N = %D",N);
814:   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.");

816:   /*
817:      Split the subdomains equally among all processors
818:   */
819:   MPI_Comm_rank(PetscObjectComm((PetscObject)pc),&rank);
820:   MPI_Comm_size(PetscObjectComm((PetscObject)pc),&size);
821:   n    = N/size + ((N % size) > rank);
822:   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);
823:   if (pc->setupcalled && n != osm->n_local_true) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONGSTATE,"PCASMSetTotalSubdomains() should be called before PCSetUp().");
824:   if (!pc->setupcalled) {
825:     PCASMDestroySubdomains(osm->n_local_true,osm->is,osm->is_local);

827:     osm->n_local_true = n;
828:     osm->is           = NULL;
829:     osm->is_local     = NULL;
830:   }
831:   return(0);
832: }

834: static PetscErrorCode  PCASMSetOverlap_ASM(PC pc,PetscInt ovl)
835: {
836:   PC_ASM *osm = (PC_ASM*)pc->data;

839:   if (ovl < 0) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_OUTOFRANGE,"Negative overlap value requested");
840:   if (pc->setupcalled && ovl != osm->overlap) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"PCASMSetOverlap() should be called before PCSetUp().");
841:   if (!pc->setupcalled) osm->overlap = ovl;
842:   return(0);
843: }

845: static PetscErrorCode  PCASMSetType_ASM(PC pc,PCASMType type)
846: {
847:   PC_ASM *osm = (PC_ASM*)pc->data;

850:   osm->type     = type;
851:   osm->type_set = PETSC_TRUE;
852:   return(0);
853: }

855: static PetscErrorCode  PCASMGetType_ASM(PC pc,PCASMType *type)
856: {
857:   PC_ASM *osm = (PC_ASM*)pc->data;

860:   *type = osm->type;
861:   return(0);
862: }

864: static PetscErrorCode  PCASMSetLocalType_ASM(PC pc, PCCompositeType type)
865: {
866:   PC_ASM *osm = (PC_ASM *) pc->data;

869:   if (type != PC_COMPOSITE_ADDITIVE && type != PC_COMPOSITE_MULTIPLICATIVE) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Only supports additive or multiplicative as the local type");
870:   osm->loctype = type;
871:   return(0);
872: }

874: static PetscErrorCode  PCASMGetLocalType_ASM(PC pc, PCCompositeType *type)
875: {
876:   PC_ASM *osm = (PC_ASM *) pc->data;

879:   *type = osm->loctype;
880:   return(0);
881: }

883: static PetscErrorCode  PCASMSetSortIndices_ASM(PC pc,PetscBool  doSort)
884: {
885:   PC_ASM *osm = (PC_ASM*)pc->data;

888:   osm->sort_indices = doSort;
889:   return(0);
890: }

892: static PetscErrorCode  PCASMGetSubKSP_ASM(PC pc,PetscInt *n_local,PetscInt *first_local,KSP **ksp)
893: {
894:   PC_ASM         *osm = (PC_ASM*)pc->data;

898:   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");

900:   if (n_local) *n_local = osm->n_local_true;
901:   if (first_local) {
902:     MPI_Scan(&osm->n_local_true,first_local,1,MPIU_INT,MPI_SUM,PetscObjectComm((PetscObject)pc));
903:     *first_local -= osm->n_local_true;
904:   }
905:   if (ksp) {
906:     /* Assume that local solves are now different; not necessarily
907:        true though!  This flag is used only for PCView_ASM() */
908:     *ksp                   = osm->ksp;
909:     osm->same_local_solves = PETSC_FALSE;
910:   }
911:   return(0);
912: }

914: static PetscErrorCode  PCASMGetSubMatType_ASM(PC pc,MatType *sub_mat_type)
915: {
916:   PC_ASM         *osm = (PC_ASM*)pc->data;

921:   *sub_mat_type = osm->sub_mat_type;
922:   return(0);
923: }

925: static PetscErrorCode PCASMSetSubMatType_ASM(PC pc,MatType sub_mat_type)
926: {
927:   PetscErrorCode    ierr;
928:   PC_ASM            *osm = (PC_ASM*)pc->data;

932:   PetscFree(osm->sub_mat_type);
933:   PetscStrallocpy(sub_mat_type,(char**)&osm->sub_mat_type);
934:   return(0);
935: }

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

940:     Collective on pc

942:     Input Parameters:
943: +   pc - the preconditioner context
944: .   n - the number of subdomains for this processor (default value = 1)
945: .   is - the index set that defines the subdomains for this processor
946:          (or NULL for PETSc to determine subdomains)
947: -   is_local - the index sets that define the local part of the subdomains for this processor, not used unless PCASMType is PC_ASM_RESTRICT
948:          (or NULL to not provide these)

950:     Options Database Key:
951:     To set the total number of subdomain blocks rather than specify the
952:     index sets, use the option
953: .    -pc_asm_local_blocks <blks> - Sets local blocks

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

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

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

962:     If is_local is provided and PCASMType is PC_ASM_RESTRICT then the solution only over the is_local region is interpolated
963:     back to form the global solution (this is the standard restricted additive Schwarz method)

965:     If the is_local is provided and PCASMType is PC_ASM_INTERPOLATE or PC_ASM_NONE then an error is generated since there is
966:     no code to handle that case.

968:     Level: advanced

970: .seealso: PCASMSetTotalSubdomains(), PCASMSetOverlap(), PCASMGetSubKSP(),
971:           PCASMCreateSubdomains2D(), PCASMGetLocalSubdomains(), PCASMType, PCASMSetType()
972: @*/
973: PetscErrorCode  PCASMSetLocalSubdomains(PC pc,PetscInt n,IS is[],IS is_local[])
974: {

979:   PetscTryMethod(pc,"PCASMSetLocalSubdomains_C",(PC,PetscInt,IS[],IS[]),(pc,n,is,is_local));
980:   return(0);
981: }

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

988:     Collective on pc

990:     Input Parameters:
991: +   pc - the preconditioner context
992: .   N  - the number of subdomains for all processors
993: .   is - the index sets that define the subdomains for all processors
994:          (or NULL to ask PETSc to determine the subdomains)
995: -   is_local - the index sets that define the local part of the subdomains for this processor
996:          (or NULL to not provide this information)

998:     Options Database Key:
999:     To set the total number of subdomain blocks rather than specify the
1000:     index sets, use the option
1001: .    -pc_asm_blocks <blks> - Sets total blocks

1003:     Notes:
1004:     Currently you cannot use this to set the actual subdomains with the argument is or is_local.

1006:     By default the ASM preconditioner uses 1 block per processor.

1008:     These index sets cannot be destroyed until after completion of the
1009:     linear solves for which the ASM preconditioner is being used.

1011:     Use PCASMSetLocalSubdomains() to set local subdomains.

1013:     The IS numbering is in the parallel, global numbering of the vector for both is and is_local

1015:     Level: advanced

1017: .seealso: PCASMSetLocalSubdomains(), PCASMSetOverlap(), PCASMGetSubKSP(),
1018:           PCASMCreateSubdomains2D()
1019: @*/
1020: PetscErrorCode  PCASMSetTotalSubdomains(PC pc,PetscInt N,IS is[],IS is_local[])
1021: {

1026:   PetscTryMethod(pc,"PCASMSetTotalSubdomains_C",(PC,PetscInt,IS[],IS[]),(pc,N,is,is_local));
1027:   return(0);
1028: }

1030: /*@
1031:     PCASMSetOverlap - Sets the overlap between a pair of subdomains for the
1032:     additive Schwarz preconditioner.  Either all or no processors in the
1033:     PC communicator must call this routine.

1035:     Logically Collective on pc

1037:     Input Parameters:
1038: +   pc  - the preconditioner context
1039: -   ovl - the amount of overlap between subdomains (ovl >= 0, default value = 1)

1041:     Options Database Key:
1042: .   -pc_asm_overlap <ovl> - Sets overlap

1044:     Notes:
1045:     By default the ASM preconditioner uses 1 block per processor.  To use
1046:     multiple blocks per perocessor, see PCASMSetTotalSubdomains() and
1047:     PCASMSetLocalSubdomains() (and the option -pc_asm_blocks <blks>).

1049:     The overlap defaults to 1, so if one desires that no additional
1050:     overlap be computed beyond what may have been set with a call to
1051:     PCASMSetTotalSubdomains() or PCASMSetLocalSubdomains(), then ovl
1052:     must be set to be 0.  In particular, if one does not explicitly set
1053:     the subdomains an application code, then all overlap would be computed
1054:     internally by PETSc, and using an overlap of 0 would result in an ASM
1055:     variant that is equivalent to the block Jacobi preconditioner.

1057:     The default algorithm used by PETSc to increase overlap is fast, but not scalable,
1058:     use the option -mat_increase_overlap_scalable when the problem and number of processes is large.

1060:     Note that one can define initial index sets with any overlap via
1061:     PCASMSetLocalSubdomains(); the routine
1062:     PCASMSetOverlap() merely allows PETSc to extend that overlap further
1063:     if desired.

1065:     Level: intermediate

1067: .seealso: PCASMSetTotalSubdomains(), PCASMSetLocalSubdomains(), PCASMGetSubKSP(),
1068:           PCASMCreateSubdomains2D(), PCASMGetLocalSubdomains(), MatIncreaseOverlap()
1069: @*/
1070: PetscErrorCode  PCASMSetOverlap(PC pc,PetscInt ovl)
1071: {

1077:   PetscTryMethod(pc,"PCASMSetOverlap_C",(PC,PetscInt),(pc,ovl));
1078:   return(0);
1079: }

1081: /*@
1082:     PCASMSetType - Sets the type of restriction and interpolation used
1083:     for local problems in the additive Schwarz method.

1085:     Logically Collective on pc

1087:     Input Parameters:
1088: +   pc  - the preconditioner context
1089: -   type - variant of ASM, one of
1090: .vb
1091:       PC_ASM_BASIC       - full interpolation and restriction
1092:       PC_ASM_RESTRICT    - full restriction, local processor interpolation
1093:       PC_ASM_INTERPOLATE - full interpolation, local processor restriction
1094:       PC_ASM_NONE        - local processor restriction and interpolation
1095: .ve

1097:     Options Database Key:
1098: .   -pc_asm_type [basic,restrict,interpolate,none] - Sets ASM type

1100:     Notes:
1101:     if the is_local arguments are passed to PCASMSetLocalSubdomains() then they are used when PC_ASM_RESTRICT has been selected
1102:     to limit the local processor interpolation

1104:     Level: intermediate

1106: .seealso: PCASMSetTotalSubdomains(), PCASMSetTotalSubdomains(), PCASMGetSubKSP(),
1107:           PCASMCreateSubdomains2D(), PCASMType, PCASMSetLocalType(), PCASMGetLocalType()
1108: @*/
1109: PetscErrorCode  PCASMSetType(PC pc,PCASMType type)
1110: {

1116:   PetscTryMethod(pc,"PCASMSetType_C",(PC,PCASMType),(pc,type));
1117:   return(0);
1118: }

1120: /*@
1121:     PCASMGetType - Gets the type of restriction and interpolation used
1122:     for local problems in the additive Schwarz method.

1124:     Logically Collective on pc

1126:     Input Parameter:
1127: .   pc  - the preconditioner context

1129:     Output Parameter:
1130: .   type - variant of ASM, one of

1132: .vb
1133:       PC_ASM_BASIC       - full interpolation and restriction
1134:       PC_ASM_RESTRICT    - full restriction, local processor interpolation
1135:       PC_ASM_INTERPOLATE - full interpolation, local processor restriction
1136:       PC_ASM_NONE        - local processor restriction and interpolation
1137: .ve

1139:     Options Database Key:
1140: .   -pc_asm_type [basic,restrict,interpolate,none] - Sets ASM type

1142:     Level: intermediate

1144: .seealso: PCASMSetTotalSubdomains(), PCASMSetTotalSubdomains(), PCASMGetSubKSP(),
1145:           PCASMCreateSubdomains2D(), PCASMType, PCASMSetType(), PCASMSetLocalType(), PCASMGetLocalType()
1146: @*/
1147: PetscErrorCode  PCASMGetType(PC pc,PCASMType *type)
1148: {

1153:   PetscUseMethod(pc,"PCASMGetType_C",(PC,PCASMType*),(pc,type));
1154:   return(0);
1155: }

1157: /*@
1158:   PCASMSetLocalType - Sets the type of composition used for local problems in the additive Schwarz method.

1160:   Logically Collective on pc

1162:   Input Parameters:
1163: + pc  - the preconditioner context
1164: - type - type of composition, one of
1165: .vb
1166:   PC_COMPOSITE_ADDITIVE       - local additive combination
1167:   PC_COMPOSITE_MULTIPLICATIVE - local multiplicative combination
1168: .ve

1170:   Options Database Key:
1171: . -pc_asm_local_type [additive,multiplicative] - Sets local solver composition type

1173:   Level: intermediate

1175: .seealso: PCASMSetType(), PCASMGetType(), PCASMGetLocalType(), PCASM, PCASMType, PCASMSetType(), PCASMGetType(), PCCompositeType
1176: @*/
1177: PetscErrorCode PCASMSetLocalType(PC pc, PCCompositeType type)
1178: {

1184:   PetscTryMethod(pc, "PCASMSetLocalType_C", (PC, PCCompositeType), (pc, type));
1185:   return(0);
1186: }

1188: /*@
1189:   PCASMGetLocalType - Gets the type of composition used for local problems in the additive Schwarz method.

1191:   Logically Collective on pc

1193:   Input Parameter:
1194: . pc  - the preconditioner context

1196:   Output Parameter:
1197: . type - type of composition, one of
1198: .vb
1199:   PC_COMPOSITE_ADDITIVE       - local additive combination
1200:   PC_COMPOSITE_MULTIPLICATIVE - local multiplicative combination
1201: .ve

1203:   Options Database Key:
1204: . -pc_asm_local_type [additive,multiplicative] - Sets local solver composition type

1206:   Level: intermediate

1208: .seealso: PCASMSetType(), PCASMGetType(), PCASMSetLocalType(), PCASMCreate(), PCASMType, PCASMSetType(), PCASMGetType(), PCCompositeType
1209: @*/
1210: PetscErrorCode PCASMGetLocalType(PC pc, PCCompositeType *type)
1211: {

1217:   PetscUseMethod(pc, "PCASMGetLocalType_C", (PC, PCCompositeType *), (pc, type));
1218:   return(0);
1219: }

1221: /*@
1222:     PCASMSetSortIndices - Determines whether subdomain indices are sorted.

1224:     Logically Collective on pc

1226:     Input Parameters:
1227: +   pc  - the preconditioner context
1228: -   doSort - sort the subdomain indices

1230:     Level: intermediate

1232: .seealso: PCASMSetLocalSubdomains(), PCASMSetTotalSubdomains(), PCASMGetSubKSP(),
1233:           PCASMCreateSubdomains2D()
1234: @*/
1235: PetscErrorCode  PCASMSetSortIndices(PC pc,PetscBool doSort)
1236: {

1242:   PetscTryMethod(pc,"PCASMSetSortIndices_C",(PC,PetscBool),(pc,doSort));
1243:   return(0);
1244: }

1246: /*@C
1247:    PCASMGetSubKSP - Gets the local KSP contexts for all blocks on
1248:    this processor.

1250:    Collective on pc iff first_local is requested

1252:    Input Parameter:
1253: .  pc - the preconditioner context

1255:    Output Parameters:
1256: +  n_local - the number of blocks on this processor or NULL
1257: .  first_local - the global number of the first block on this processor or NULL,
1258:                  all processors must request or all must pass NULL
1259: -  ksp - the array of KSP contexts

1261:    Note:
1262:    After PCASMGetSubKSP() the array of KSPes is not to be freed.

1264:    You must call KSPSetUp() before calling PCASMGetSubKSP().

1266:    Fortran note:
1267:    The output argument 'ksp' must be an array of sufficient length or PETSC_NULL_KSP. The latter can be used to learn the necessary length.

1269:    Level: advanced

1271: .seealso: PCASMSetTotalSubdomains(), PCASMSetTotalSubdomains(), PCASMSetOverlap(),
1272:           PCASMCreateSubdomains2D(),
1273: @*/
1274: PetscErrorCode  PCASMGetSubKSP(PC pc,PetscInt *n_local,PetscInt *first_local,KSP *ksp[])
1275: {

1280:   PetscUseMethod(pc,"PCASMGetSubKSP_C",(PC,PetscInt*,PetscInt*,KSP **),(pc,n_local,first_local,ksp));
1281:   return(0);
1282: }

1284: /* -------------------------------------------------------------------------------------*/
1285: /*MC
1286:    PCASM - Use the (restricted) additive Schwarz method, each block is (approximately) solved with
1287:            its own KSP object.

1289:    Options Database Keys:
1290: +  -pc_asm_blocks <blks> - Sets total blocks
1291: .  -pc_asm_overlap <ovl> - Sets overlap
1292: .  -pc_asm_type [basic,restrict,interpolate,none] - Sets ASM type, default is restrict
1293: -  -pc_asm_local_type [additive, multiplicative] - Sets ASM type, default is additive

1295:      IMPORTANT: If you run with, for example, 3 blocks on 1 processor or 3 blocks on 3 processors you
1296:       will get a different convergence rate due to the default option of -pc_asm_type restrict. Use
1297:       -pc_asm_type basic to use the standard ASM.

1299:    Notes:
1300:     Each processor can have one or more blocks, but a block cannot be shared by more
1301:      than one processor. Use PCGASM for subdomains shared by multiple processes. Defaults to one block per processor.

1303:      To set options on the solvers for each block append -sub_ to all the KSP, and PC
1304:         options database keys. For example, -sub_pc_type ilu -sub_pc_factor_levels 1 -sub_ksp_type preonly

1306:      To set the options on the solvers separate for each block call PCASMGetSubKSP()
1307:          and set the options directly on the resulting KSP object (you can access its PC
1308:          with KSPGetPC())

1310:    Level: beginner

1312:     References:
1313: +   1. - M Dryja, OB Widlund, An additive variant of the Schwarz alternating method for the case of many subregions
1314:      Courant Institute, New York University Technical report
1315: -   2. - Barry Smith, Petter Bjorstad, and William Gropp, Domain Decompositions: Parallel Multilevel Methods for Elliptic Partial Differential Equations,
1316:     Cambridge University Press.

1318: .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC,
1319:            PCBJACOBI, PCASMGetSubKSP(), PCASMSetLocalSubdomains(), PCASMType, PCASMGetType(), PCASMSetLocalType(), PCASMGetLocalType()
1320:            PCASMSetTotalSubdomains(), PCSetModifySubMatrices(), PCASMSetOverlap(), PCASMSetType(), PCCompositeType

1322: M*/

1324: PETSC_EXTERN PetscErrorCode PCCreate_ASM(PC pc)
1325: {
1327:   PC_ASM         *osm;

1330:   PetscNewLog(pc,&osm);

1332:   osm->n                 = PETSC_DECIDE;
1333:   osm->n_local           = 0;
1334:   osm->n_local_true      = PETSC_DECIDE;
1335:   osm->overlap           = 1;
1336:   osm->ksp               = NULL;
1337:   osm->restriction       = NULL;
1338:   osm->lprolongation     = NULL;
1339:   osm->lrestriction      = NULL;
1340:   osm->x                 = NULL;
1341:   osm->y                 = NULL;
1342:   osm->is                = NULL;
1343:   osm->is_local          = NULL;
1344:   osm->mat               = NULL;
1345:   osm->pmat              = NULL;
1346:   osm->type              = PC_ASM_RESTRICT;
1347:   osm->loctype           = PC_COMPOSITE_ADDITIVE;
1348:   osm->same_local_solves = PETSC_TRUE;
1349:   osm->sort_indices      = PETSC_TRUE;
1350:   osm->dm_subdomains     = PETSC_FALSE;
1351:   osm->sub_mat_type      = NULL;

1353:   pc->data                 = (void*)osm;
1354:   pc->ops->apply           = PCApply_ASM;
1355:   pc->ops->matapply        = PCMatApply_ASM;
1356:   pc->ops->applytranspose  = PCApplyTranspose_ASM;
1357:   pc->ops->setup           = PCSetUp_ASM;
1358:   pc->ops->reset           = PCReset_ASM;
1359:   pc->ops->destroy         = PCDestroy_ASM;
1360:   pc->ops->setfromoptions  = PCSetFromOptions_ASM;
1361:   pc->ops->setuponblocks   = PCSetUpOnBlocks_ASM;
1362:   pc->ops->view            = PCView_ASM;
1363:   pc->ops->applyrichardson = NULL;

1365:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetLocalSubdomains_C",PCASMSetLocalSubdomains_ASM);
1366:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetTotalSubdomains_C",PCASMSetTotalSubdomains_ASM);
1367:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetOverlap_C",PCASMSetOverlap_ASM);
1368:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetType_C",PCASMSetType_ASM);
1369:   PetscObjectComposeFunction((PetscObject)pc,"PCASMGetType_C",PCASMGetType_ASM);
1370:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetLocalType_C",PCASMSetLocalType_ASM);
1371:   PetscObjectComposeFunction((PetscObject)pc,"PCASMGetLocalType_C",PCASMGetLocalType_ASM);
1372:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetSortIndices_C",PCASMSetSortIndices_ASM);
1373:   PetscObjectComposeFunction((PetscObject)pc,"PCASMGetSubKSP_C",PCASMGetSubKSP_ASM);
1374:   PetscObjectComposeFunction((PetscObject)pc,"PCASMGetSubMatType_C",PCASMGetSubMatType_ASM);
1375:   PetscObjectComposeFunction((PetscObject)pc,"PCASMSetSubMatType_C",PCASMSetSubMatType_ASM);
1376:   return(0);
1377: }

1379: /*@C
1380:    PCASMCreateSubdomains - Creates the index sets for the overlapping Schwarz
1381:    preconditioner for a any problem on a general grid.

1383:    Collective

1385:    Input Parameters:
1386: +  A - The global matrix operator
1387: -  n - the number of local blocks

1389:    Output Parameters:
1390: .  outis - the array of index sets defining the subdomains

1392:    Level: advanced

1394:    Note: this generates nonoverlapping subdomains; the PCASM will generate the overlap
1395:     from these if you use PCASMSetLocalSubdomains()

1397:     In the Fortran version you must provide the array outis[] already allocated of length n.

1399: .seealso: PCASMSetLocalSubdomains(), PCASMDestroySubdomains()
1400: @*/
1401: PetscErrorCode  PCASMCreateSubdomains(Mat A, PetscInt n, IS* outis[])
1402: {
1403:   MatPartitioning mpart;
1404:   const char      *prefix;
1405:   PetscInt        i,j,rstart,rend,bs;
1406:   PetscBool       hasop, isbaij = PETSC_FALSE,foundpart = PETSC_FALSE;
1407:   Mat             Ad     = NULL, adj;
1408:   IS              ispart,isnumb,*is;
1409:   PetscErrorCode  ierr;

1414:   if (n < 1) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_WRONG,"number of local blocks must be > 0, n = %D",n);

1416:   /* Get prefix, row distribution, and block size */
1417:   MatGetOptionsPrefix(A,&prefix);
1418:   MatGetOwnershipRange(A,&rstart,&rend);
1419:   MatGetBlockSize(A,&bs);
1420:   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);

1422:   /* Get diagonal block from matrix if possible */
1423:   MatHasOperation(A,MATOP_GET_DIAGONAL_BLOCK,&hasop);
1424:   if (hasop) {
1425:     MatGetDiagonalBlock(A,&Ad);
1426:   }
1427:   if (Ad) {
1428:     PetscObjectBaseTypeCompare((PetscObject)Ad,MATSEQBAIJ,&isbaij);
1429:     if (!isbaij) {PetscObjectBaseTypeCompare((PetscObject)Ad,MATSEQSBAIJ,&isbaij);}
1430:   }
1431:   if (Ad && n > 1) {
1432:     PetscBool match,done;
1433:     /* Try to setup a good matrix partitioning if available */
1434:     MatPartitioningCreate(PETSC_COMM_SELF,&mpart);
1435:     PetscObjectSetOptionsPrefix((PetscObject)mpart,prefix);
1436:     MatPartitioningSetFromOptions(mpart);
1437:     PetscObjectTypeCompare((PetscObject)mpart,MATPARTITIONINGCURRENT,&match);
1438:     if (!match) {
1439:       PetscObjectTypeCompare((PetscObject)mpart,MATPARTITIONINGSQUARE,&match);
1440:     }
1441:     if (!match) { /* assume a "good" partitioner is available */
1442:       PetscInt       na;
1443:       const PetscInt *ia,*ja;
1444:       MatGetRowIJ(Ad,0,PETSC_TRUE,isbaij,&na,&ia,&ja,&done);
1445:       if (done) {
1446:         /* Build adjacency matrix by hand. Unfortunately a call to
1447:            MatConvert(Ad,MATMPIADJ,MAT_INITIAL_MATRIX,&adj) will
1448:            remove the block-aij structure and we cannot expect
1449:            MatPartitioning to split vertices as we need */
1450:         PetscInt       i,j,len,nnz,cnt,*iia=NULL,*jja=NULL;
1451:         const PetscInt *row;
1452:         nnz = 0;
1453:         for (i=0; i<na; i++) { /* count number of nonzeros */
1454:           len = ia[i+1] - ia[i];
1455:           row = ja + ia[i];
1456:           for (j=0; j<len; j++) {
1457:             if (row[j] == i) { /* don't count diagonal */
1458:               len--; break;
1459:             }
1460:           }
1461:           nnz += len;
1462:         }
1463:         PetscMalloc1(na+1,&iia);
1464:         PetscMalloc1(nnz,&jja);
1465:         nnz    = 0;
1466:         iia[0] = 0;
1467:         for (i=0; i<na; i++) { /* fill adjacency */
1468:           cnt = 0;
1469:           len = ia[i+1] - ia[i];
1470:           row = ja + ia[i];
1471:           for (j=0; j<len; j++) {
1472:             if (row[j] != i) { /* if not diagonal */
1473:               jja[nnz+cnt++] = row[j];
1474:             }
1475:           }
1476:           nnz     += cnt;
1477:           iia[i+1] = nnz;
1478:         }
1479:         /* Partitioning of the adjacency matrix */
1480:         MatCreateMPIAdj(PETSC_COMM_SELF,na,na,iia,jja,NULL,&adj);
1481:         MatPartitioningSetAdjacency(mpart,adj);
1482:         MatPartitioningSetNParts(mpart,n);
1483:         MatPartitioningApply(mpart,&ispart);
1484:         ISPartitioningToNumbering(ispart,&isnumb);
1485:         MatDestroy(&adj);
1486:         foundpart = PETSC_TRUE;
1487:       }
1488:       MatRestoreRowIJ(Ad,0,PETSC_TRUE,isbaij,&na,&ia,&ja,&done);
1489:     }
1490:     MatPartitioningDestroy(&mpart);
1491:   }

1493:   PetscMalloc1(n,&is);
1494:   *outis = is;

1496:   if (!foundpart) {

1498:     /* Partitioning by contiguous chunks of rows */

1500:     PetscInt mbs   = (rend-rstart)/bs;
1501:     PetscInt start = rstart;
1502:     for (i=0; i<n; i++) {
1503:       PetscInt count = (mbs/n + ((mbs % n) > i)) * bs;
1504:       ISCreateStride(PETSC_COMM_SELF,count,start,1,&is[i]);
1505:       start += count;
1506:     }

1508:   } else {

1510:     /* Partitioning by adjacency of diagonal block  */

1512:     const PetscInt *numbering;
1513:     PetscInt       *count,nidx,*indices,*newidx,start=0;
1514:     /* Get node count in each partition */
1515:     PetscMalloc1(n,&count);
1516:     ISPartitioningCount(ispart,n,count);
1517:     if (isbaij && bs > 1) { /* adjust for the block-aij case */
1518:       for (i=0; i<n; i++) count[i] *= bs;
1519:     }
1520:     /* Build indices from node numbering */
1521:     ISGetLocalSize(isnumb,&nidx);
1522:     PetscMalloc1(nidx,&indices);
1523:     for (i=0; i<nidx; i++) indices[i] = i; /* needs to be initialized */
1524:     ISGetIndices(isnumb,&numbering);
1525:     PetscSortIntWithPermutation(nidx,numbering,indices);
1526:     ISRestoreIndices(isnumb,&numbering);
1527:     if (isbaij && bs > 1) { /* adjust for the block-aij case */
1528:       PetscMalloc1(nidx*bs,&newidx);
1529:       for (i=0; i<nidx; i++) {
1530:         for (j=0; j<bs; j++) newidx[i*bs+j] = indices[i]*bs + j;
1531:       }
1532:       PetscFree(indices);
1533:       nidx   *= bs;
1534:       indices = newidx;
1535:     }
1536:     /* Shift to get global indices */
1537:     for (i=0; i<nidx; i++) indices[i] += rstart;

1539:     /* Build the index sets for each block */
1540:     for (i=0; i<n; i++) {
1541:       ISCreateGeneral(PETSC_COMM_SELF,count[i],&indices[start],PETSC_COPY_VALUES,&is[i]);
1542:       ISSort(is[i]);
1543:       start += count[i];
1544:     }

1546:     PetscFree(count);
1547:     PetscFree(indices);
1548:     ISDestroy(&isnumb);
1549:     ISDestroy(&ispart);

1551:   }
1552:   return(0);
1553: }

1555: /*@C
1556:    PCASMDestroySubdomains - Destroys the index sets created with
1557:    PCASMCreateSubdomains(). Should be called after setting subdomains
1558:    with PCASMSetLocalSubdomains().

1560:    Collective

1562:    Input Parameters:
1563: +  n - the number of index sets
1564: .  is - the array of index sets
1565: -  is_local - the array of local index sets, can be NULL

1567:    Level: advanced

1569: .seealso: PCASMCreateSubdomains(), PCASMSetLocalSubdomains()
1570: @*/
1571: PetscErrorCode  PCASMDestroySubdomains(PetscInt n, IS is[], IS is_local[])
1572: {
1573:   PetscInt       i;

1577:   if (n <= 0) return(0);
1578:   if (is) {
1580:     for (i=0; i<n; i++) { ISDestroy(&is[i]); }
1581:     PetscFree(is);
1582:   }
1583:   if (is_local) {
1585:     for (i=0; i<n; i++) { ISDestroy(&is_local[i]); }
1586:     PetscFree(is_local);
1587:   }
1588:   return(0);
1589: }

1591: /*@
1592:    PCASMCreateSubdomains2D - Creates the index sets for the overlapping Schwarz
1593:    preconditioner for a two-dimensional problem on a regular grid.

1595:    Not Collective

1597:    Input Parameters:
1598: +  m, n - the number of mesh points in the x and y directions
1599: .  M, N - the number of subdomains in the x and y directions
1600: .  dof - degrees of freedom per node
1601: -  overlap - overlap in mesh lines

1603:    Output Parameters:
1604: +  Nsub - the number of subdomains created
1605: .  is - array of index sets defining overlapping (if overlap > 0) subdomains
1606: -  is_local - array of index sets defining non-overlapping subdomains

1608:    Note:
1609:    Presently PCAMSCreateSubdomains2d() is valid only for sequential
1610:    preconditioners.  More general related routines are
1611:    PCASMSetTotalSubdomains() and PCASMSetLocalSubdomains().

1613:    Level: advanced

1615: .seealso: PCASMSetTotalSubdomains(), PCASMSetLocalSubdomains(), PCASMGetSubKSP(),
1616:           PCASMSetOverlap()
1617: @*/
1618: PetscErrorCode  PCASMCreateSubdomains2D(PetscInt m,PetscInt n,PetscInt M,PetscInt N,PetscInt dof,PetscInt overlap,PetscInt *Nsub,IS **is,IS **is_local)
1619: {
1620:   PetscInt       i,j,height,width,ystart,xstart,yleft,yright,xleft,xright,loc_outer;
1622:   PetscInt       nidx,*idx,loc,ii,jj,count;

1625:   if (dof != 1) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP," ");

1627:   *Nsub     = N*M;
1628:   PetscMalloc1(*Nsub,is);
1629:   PetscMalloc1(*Nsub,is_local);
1630:   ystart    = 0;
1631:   loc_outer = 0;
1632:   for (i=0; i<N; i++) {
1633:     height = n/N + ((n % N) > i); /* height of subdomain */
1634:     if (height < 2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many N subdomains for mesh dimension n");
1635:     yleft  = ystart - overlap; if (yleft < 0) yleft = 0;
1636:     yright = ystart + height + overlap; if (yright > n) yright = n;
1637:     xstart = 0;
1638:     for (j=0; j<M; j++) {
1639:       width = m/M + ((m % M) > j); /* width of subdomain */
1640:       if (width < 2) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Too many M subdomains for mesh dimension m");
1641:       xleft  = xstart - overlap; if (xleft < 0) xleft = 0;
1642:       xright = xstart + width + overlap; if (xright > m) xright = m;
1643:       nidx   = (xright - xleft)*(yright - yleft);
1644:       PetscMalloc1(nidx,&idx);
1645:       loc    = 0;
1646:       for (ii=yleft; ii<yright; ii++) {
1647:         count = m*ii + xleft;
1648:         for (jj=xleft; jj<xright; jj++) idx[loc++] = count++;
1649:       }
1650:       ISCreateGeneral(PETSC_COMM_SELF,nidx,idx,PETSC_COPY_VALUES,(*is)+loc_outer);
1651:       if (overlap == 0) {
1652:         PetscObjectReference((PetscObject)(*is)[loc_outer]);

1654:         (*is_local)[loc_outer] = (*is)[loc_outer];
1655:       } else {
1656:         for (loc=0,ii=ystart; ii<ystart+height; ii++) {
1657:           for (jj=xstart; jj<xstart+width; jj++) {
1658:             idx[loc++] = m*ii + jj;
1659:           }
1660:         }
1661:         ISCreateGeneral(PETSC_COMM_SELF,loc,idx,PETSC_COPY_VALUES,*is_local+loc_outer);
1662:       }
1663:       PetscFree(idx);
1664:       xstart += width;
1665:       loc_outer++;
1666:     }
1667:     ystart += height;
1668:   }
1669:   for (i=0; i<*Nsub; i++) { ISSort((*is)[i]); }
1670:   return(0);
1671: }

1673: /*@C
1674:     PCASMGetLocalSubdomains - Gets the local subdomains (for this processor
1675:     only) for the additive Schwarz preconditioner.

1677:     Not Collective

1679:     Input Parameter:
1680: .   pc - the preconditioner context

1682:     Output Parameters:
1683: +   n - the number of subdomains for this processor (default value = 1)
1684: .   is - the index sets that define the subdomains for this processor
1685: -   is_local - the index sets that define the local part of the subdomains for this processor (can be NULL)


1688:     Notes:
1689:     The IS numbering is in the parallel, global numbering of the vector.

1691:     Level: advanced

1693: .seealso: PCASMSetTotalSubdomains(), PCASMSetOverlap(), PCASMGetSubKSP(),
1694:           PCASMCreateSubdomains2D(), PCASMSetLocalSubdomains(), PCASMGetLocalSubmatrices()
1695: @*/
1696: PetscErrorCode  PCASMGetLocalSubdomains(PC pc,PetscInt *n,IS *is[],IS *is_local[])
1697: {
1698:   PC_ASM         *osm = (PC_ASM*)pc->data;
1700:   PetscBool      match;

1706:   PetscObjectTypeCompare((PetscObject)pc,PCASM,&match);
1707:   if (!match) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONG,"PC is not a PCASM");
1708:   if (n) *n = osm->n_local_true;
1709:   if (is) *is = osm->is;
1710:   if (is_local) *is_local = osm->is_local;
1711:   return(0);
1712: }

1714: /*@C
1715:     PCASMGetLocalSubmatrices - Gets the local submatrices (for this processor
1716:     only) for the additive Schwarz preconditioner.

1718:     Not Collective

1720:     Input Parameter:
1721: .   pc - the preconditioner context

1723:     Output Parameters:
1724: +   n - the number of matrices for this processor (default value = 1)
1725: -   mat - the matrices

1727:     Level: advanced

1729:     Notes:
1730:     Call after PCSetUp() (or KSPSetUp()) but before PCApply() and before PCSetUpOnBlocks())

1732:            Usually one would use PCSetModifySubMatrices() to change the submatrices in building the preconditioner.

1734: .seealso: PCASMSetTotalSubdomains(), PCASMSetOverlap(), PCASMGetSubKSP(),
1735:           PCASMCreateSubdomains2D(), PCASMSetLocalSubdomains(), PCASMGetLocalSubdomains(), PCSetModifySubMatrices()
1736: @*/
1737: PetscErrorCode  PCASMGetLocalSubmatrices(PC pc,PetscInt *n,Mat *mat[])
1738: {
1739:   PC_ASM         *osm;
1741:   PetscBool      match;

1747:   if (!pc->setupcalled) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONGSTATE,"Must call after KSPSetUp() or PCSetUp().");
1748:   PetscObjectTypeCompare((PetscObject)pc,PCASM,&match);
1749:   if (!match) {
1750:     if (n) *n = 0;
1751:     if (mat) *mat = NULL;
1752:   } else {
1753:     osm = (PC_ASM*)pc->data;
1754:     if (n) *n = osm->n_local_true;
1755:     if (mat) *mat = osm->pmat;
1756:   }
1757:   return(0);
1758: }

1760: /*@
1761:     PCASMSetDMSubdomains - Indicates whether to use DMCreateDomainDecomposition() to define the subdomains, whenever possible.

1763:     Logically Collective

1765:     Input Parameter:
1766: +   pc  - the preconditioner
1767: -   flg - boolean indicating whether to use subdomains defined by the DM

1769:     Options Database Key:
1770: .   -pc_asm_dm_subdomains

1772:     Level: intermediate

1774:     Notes:
1775:     PCASMSetTotalSubdomains() and PCASMSetOverlap() take precedence over PCASMSetDMSubdomains(),
1776:     so setting either of the first two effectively turns the latter off.

1778: .seealso: PCASMGetDMSubdomains(), PCASMSetTotalSubdomains(), PCASMSetOverlap()
1779:           PCASMCreateSubdomains2D(), PCASMSetLocalSubdomains(), PCASMGetLocalSubdomains()
1780: @*/
1781: PetscErrorCode  PCASMSetDMSubdomains(PC pc,PetscBool flg)
1782: {
1783:   PC_ASM         *osm = (PC_ASM*)pc->data;
1785:   PetscBool      match;

1790:   if (pc->setupcalled) SETERRQ(((PetscObject)pc)->comm,PETSC_ERR_ARG_WRONGSTATE,"Not for a setup PC.");
1791:   PetscObjectTypeCompare((PetscObject)pc,PCASM,&match);
1792:   if (match) {
1793:     osm->dm_subdomains = flg;
1794:   }
1795:   return(0);
1796: }

1798: /*@
1799:     PCASMGetDMSubdomains - Returns flag indicating whether to use DMCreateDomainDecomposition() to define the subdomains, whenever possible.
1800:     Not Collective

1802:     Input Parameter:
1803: .   pc  - the preconditioner

1805:     Output Parameter:
1806: .   flg - boolean indicating whether to use subdomains defined by the DM

1808:     Level: intermediate

1810: .seealso: PCASMSetDMSubdomains(), PCASMSetTotalSubdomains(), PCASMSetOverlap()
1811:           PCASMCreateSubdomains2D(), PCASMSetLocalSubdomains(), PCASMGetLocalSubdomains()
1812: @*/
1813: PetscErrorCode  PCASMGetDMSubdomains(PC pc,PetscBool* flg)
1814: {
1815:   PC_ASM         *osm = (PC_ASM*)pc->data;
1817:   PetscBool      match;

1822:   PetscObjectTypeCompare((PetscObject)pc,PCASM,&match);
1823:   if (match) *flg = osm->dm_subdomains;
1824:   else *flg = PETSC_FALSE;
1825:   return(0);
1826: }

1828: /*@
1829:      PCASMGetSubMatType - Gets the matrix type used for ASM subsolves, as a string.

1831:    Not Collective

1833:    Input Parameter:
1834: .  pc - the PC

1836:    Output Parameter:
1837: .  -pc_asm_sub_mat_type - name of matrix type

1839:    Level: advanced

1841: .seealso: PCASMSetSubMatType(), PCASM, PCSetType(), VecSetType(), MatType, Mat
1842: @*/
1843: PetscErrorCode  PCASMGetSubMatType(PC pc,MatType *sub_mat_type)
1844: {

1849:   PetscTryMethod(pc,"PCASMGetSubMatType_C",(PC,MatType*),(pc,sub_mat_type));
1850:   return(0);
1851: }

1853: /*@
1854:      PCASMSetSubMatType - Set the type of matrix used for ASM subsolves

1856:    Collective on Mat

1858:    Input Parameters:
1859: +  pc             - the PC object
1860: -  sub_mat_type   - matrix type

1862:    Options Database Key:
1863: .  -pc_asm_sub_mat_type  <sub_mat_type> - Sets the matrix type used for subsolves, for example, seqaijviennacl. If you specify a base name like aijviennacl, the corresponding sequential type is assumed.

1865:    Notes:
1866:    See "${PETSC_DIR}/include/petscmat.h" for available types

1868:   Level: advanced

1870: .seealso: PCASMGetSubMatType(), PCASM, PCSetType(), VecSetType(), MatType, Mat
1871: @*/
1872: PetscErrorCode PCASMSetSubMatType(PC pc,MatType sub_mat_type)
1873: {

1878:   PetscTryMethod(pc,"PCASMSetSubMatType_C",(PC,MatType),(pc,sub_mat_type));
1879:   return(0);
1880: }