Actual source code: asm.c

  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 <petsc/private/pcasmimpl.h>
 14: #include <petsc/private/matimpl.h>

 16: static PetscErrorCode PCView_ASM(PC pc, PetscViewer viewer)
 17: {
 18:   PC_ASM           *osm = (PC_ASM *)pc->data;
 19:   PetscMPIInt       rank;
 20:   PetscInt          i, bsz;
 21:   PetscBool         iascii, isstring;
 22:   PetscViewer       sviewer;
 23:   PetscViewerFormat format;
 24:   const char       *prefix;

 26:   PetscFunctionBegin;
 27:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
 28:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSTRING, &isstring));
 29:   if (iascii) {
 30:     char overlaps[256] = "user-defined overlap", blocks[256] = "total subdomain blocks not yet set";
 31:     if (osm->overlap >= 0) PetscCall(PetscSNPrintf(overlaps, sizeof(overlaps), "amount of overlap = %" PetscInt_FMT, osm->overlap));
 32:     if (osm->n > 0) PetscCall(PetscSNPrintf(blocks, sizeof(blocks), "total subdomain blocks = %" PetscInt_FMT, osm->n));
 33:     PetscCall(PetscViewerASCIIPrintf(viewer, "  %s, %s\n", blocks, overlaps));
 34:     PetscCall(PetscViewerASCIIPrintf(viewer, "  restriction/interpolation type - %s\n", PCASMTypes[osm->type]));
 35:     if (osm->dm_subdomains) PetscCall(PetscViewerASCIIPrintf(viewer, "  Additive Schwarz: using DM to define subdomains\n"));
 36:     if (osm->loctype != PC_COMPOSITE_ADDITIVE) PetscCall(PetscViewerASCIIPrintf(viewer, "  Additive Schwarz: local solve composition type - %s\n", PCCompositeTypes[osm->loctype]));
 37:     PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)pc), &rank));
 38:     PetscCall(PetscViewerGetFormat(viewer, &format));
 39:     if (format != PETSC_VIEWER_ASCII_INFO_DETAIL) {
 40:       if (osm->ksp) {
 41:         PetscCall(PetscViewerASCIIPrintf(viewer, "  Local solver information for first block is in the following KSP and PC objects on rank 0:\n"));
 42:         PetscCall(PCGetOptionsPrefix(pc, &prefix));
 43:         PetscCall(PetscViewerASCIIPrintf(viewer, "  Use -%sksp_view ::ascii_info_detail to display information for all blocks\n", prefix ? prefix : ""));
 44:         PetscCall(PetscViewerGetSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
 45:         if (rank == 0) {
 46:           PetscCall(PetscViewerASCIIPushTab(sviewer));
 47:           PetscCall(KSPView(osm->ksp[0], sviewer));
 48:           PetscCall(PetscViewerASCIIPopTab(sviewer));
 49:         }
 50:         PetscCall(PetscViewerRestoreSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
 51:       }
 52:     } else {
 53:       PetscCall(PetscViewerASCIIPushSynchronized(viewer));
 54:       PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "  [%d] number of local blocks = %" PetscInt_FMT "\n", rank, osm->n_local_true));
 55:       PetscCall(PetscViewerFlush(viewer));
 56:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Local solver information for each block is in the following KSP and PC objects:\n"));
 57:       PetscCall(PetscViewerASCIIPushTab(viewer));
 58:       PetscCall(PetscViewerASCIIPrintf(viewer, "- - - - - - - - - - - - - - - - - -\n"));
 59:       PetscCall(PetscViewerGetSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
 60:       for (i = 0; i < osm->n_local_true; i++) {
 61:         PetscCall(ISGetLocalSize(osm->is[i], &bsz));
 62:         PetscCall(PetscViewerASCIIPrintf(sviewer, "[%d] local block number %" PetscInt_FMT ", size = %" PetscInt_FMT "\n", rank, i, bsz));
 63:         PetscCall(KSPView(osm->ksp[i], sviewer));
 64:         PetscCall(PetscViewerASCIIPrintf(sviewer, "- - - - - - - - - - - - - - - - - -\n"));
 65:       }
 66:       PetscCall(PetscViewerRestoreSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
 67:       PetscCall(PetscViewerASCIIPopTab(viewer));
 68:       PetscCall(PetscViewerASCIIPopSynchronized(viewer));
 69:     }
 70:   } else if (isstring) {
 71:     PetscCall(PetscViewerStringSPrintf(viewer, " blocks=%" PetscInt_FMT ", overlap=%" PetscInt_FMT ", type=%s", osm->n, osm->overlap, PCASMTypes[osm->type]));
 72:     PetscCall(PetscViewerGetSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
 73:     if (osm->ksp) PetscCall(KSPView(osm->ksp[0], sviewer));
 74:     PetscCall(PetscViewerRestoreSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
 75:   }
 76:   PetscFunctionReturn(PETSC_SUCCESS);
 77: }

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

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

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

167:   PetscFunctionBegin;
168:   if (!pc->setupcalled) {
169:     PetscInt m;

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

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

211:       PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)pc), &size));
212:       if (outwork.max == 1 && outwork.sum == size) {
213:         /* osm->n_local_true = 1 on all processes, set this option may enable use of optimized MatCreateSubMatrices() implementation */
214:         PetscCall(MatSetOption(pc->pmat, MAT_SUBMAT_SINGLEIS, PETSC_TRUE));
215:       }
216:     }
217:     if (!osm->is) { /* create the index sets */
218:       PetscCall(PCASMCreateSubdomains(pc->pmat, osm->n_local_true, &osm->is));
219:     }
220:     if (osm->n_local_true > 1 && !osm->is_local) {
221:       PetscCall(PetscMalloc1(osm->n_local_true, &osm->is_local));
222:       for (i = 0; i < osm->n_local_true; i++) {
223:         if (osm->overlap > 0) { /* With positive overlap, osm->is[i] will be modified */
224:           PetscCall(ISDuplicate(osm->is[i], &osm->is_local[i]));
225:           PetscCall(ISCopy(osm->is[i], osm->is_local[i]));
226:         } else {
227:           PetscCall(PetscObjectReference((PetscObject)osm->is[i]));
228:           osm->is_local[i] = osm->is[i];
229:         }
230:       }
231:     }
232:     PetscCall(PCGetOptionsPrefix(pc, &prefix));
233:     if (osm->overlap > 0) {
234:       /* Extend the "overlapping" regions by a number of steps */
235:       PetscCall(MatIncreaseOverlap(pc->pmat, osm->n_local_true, osm->is, osm->overlap));
236:     }
237:     if (osm->sort_indices) {
238:       for (i = 0; i < osm->n_local_true; i++) {
239:         PetscCall(ISSort(osm->is[i]));
240:         if (osm->is_local) PetscCall(ISSort(osm->is_local[i]));
241:       }
242:     }
243:     flg = PETSC_FALSE;
244:     PetscCall(PetscOptionsHasName(NULL, prefix, "-pc_asm_print_subdomains", &flg));
245:     if (flg) PetscCall(PCASMPrintSubdomains(pc));
246:     if (!osm->ksp) {
247:       /* Create the local solvers */
248:       PetscCall(PetscMalloc1(osm->n_local_true, &osm->ksp));
249:       if (domain_dm) PetscCall(PetscInfo(pc, "Setting up ASM subproblems using the embedded DM\n"));
250:       for (i = 0; i < osm->n_local_true; i++) {
251:         PetscCall(KSPCreate(PETSC_COMM_SELF, &ksp));
252:         PetscCall(KSPSetNestLevel(ksp, pc->kspnestlevel));
253:         PetscCall(KSPSetErrorIfNotConverged(ksp, pc->erroriffailure));
254:         PetscCall(PetscObjectIncrementTabLevel((PetscObject)ksp, (PetscObject)pc, 1));
255:         PetscCall(KSPSetType(ksp, KSPPREONLY));
256:         PetscCall(KSPGetPC(ksp, &subpc));
257:         PetscCall(PCGetOptionsPrefix(pc, &prefix));
258:         PetscCall(KSPSetOptionsPrefix(ksp, prefix));
259:         PetscCall(KSPAppendOptionsPrefix(ksp, "sub_"));
260:         if (domain_dm) {
261:           PetscCall(KSPSetDM(ksp, domain_dm[i]));
262:           PetscCall(KSPSetDMActive(ksp, PETSC_FALSE));
263:           PetscCall(DMDestroy(&domain_dm[i]));
264:         }
265:         osm->ksp[i] = ksp;
266:       }
267:       if (domain_dm) PetscCall(PetscFree(domain_dm));
268:     }

270:     PetscCall(ISConcatenate(PETSC_COMM_SELF, osm->n_local_true, osm->is, &osm->lis));
271:     PetscCall(ISSortRemoveDups(osm->lis));
272:     PetscCall(ISGetLocalSize(osm->lis, &m));

274:     scall = MAT_INITIAL_MATRIX;
275:   } else {
276:     /*
277:        Destroy the blocks from the previous iteration
278:     */
279:     if (pc->flag == DIFFERENT_NONZERO_PATTERN) {
280:       PetscCall(MatGetNullSpaces(osm->n_local_true, osm->pmat, &nullsp));
281:       PetscCall(MatDestroyMatrices(osm->n_local_true, &osm->pmat));
282:       scall = MAT_INITIAL_MATRIX;
283:     }
284:   }

286:   /* Destroy previous submatrices of a different type than pc->pmat since MAT_REUSE_MATRIX won't work in that case */
287:   if (scall == MAT_REUSE_MATRIX && osm->sub_mat_type) {
288:     PetscCall(MatGetNullSpaces(osm->n_local_true, osm->pmat, &nullsp));
289:     if (osm->n_local_true > 0) PetscCall(MatDestroySubMatrices(osm->n_local_true, &osm->pmat));
290:     scall = MAT_INITIAL_MATRIX;
291:   }

293:   /*
294:      Extract out the submatrices
295:   */
296:   PetscCall(MatCreateSubMatrices(pc->pmat, osm->n_local_true, osm->is, osm->is, scall, &osm->pmat));
297:   if (scall == MAT_INITIAL_MATRIX) {
298:     PetscCall(PetscObjectGetOptionsPrefix((PetscObject)pc->pmat, &pprefix));
299:     for (i = 0; i < osm->n_local_true; i++) PetscCall(PetscObjectSetOptionsPrefix((PetscObject)osm->pmat[i], pprefix));
300:     if (nullsp) PetscCall(MatRestoreNullSpaces(osm->n_local_true, osm->pmat, &nullsp));
301:   }

303:   /* Convert the types of the submatrices (if needbe) */
304:   if (osm->sub_mat_type) {
305:     for (i = 0; i < osm->n_local_true; i++) PetscCall(MatConvert(osm->pmat[i], osm->sub_mat_type, MAT_INPLACE_MATRIX, &osm->pmat[i]));
306:   }

308:   if (!pc->setupcalled) {
309:     VecType vtype;

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

314:     PetscCheck(!osm->is_local || osm->n_local_true == 1 || (osm->type != PC_ASM_INTERPOLATE && osm->type != PC_ASM_NONE), PetscObjectComm((PetscObject)pc), PETSC_ERR_SUP, "Cannot use interpolate or none PCASMType if is_local was provided to PCASMSetLocalSubdomains() with more than a single subdomain");
315:     if (osm->is_local && osm->type != PC_ASM_BASIC && osm->loctype == PC_COMPOSITE_ADDITIVE) PetscCall(PetscMalloc1(osm->n_local_true, &osm->lprolongation));
316:     PetscCall(PetscMalloc1(osm->n_local_true, &osm->lrestriction));
317:     PetscCall(PetscMalloc1(osm->n_local_true, &osm->x));
318:     PetscCall(PetscMalloc1(osm->n_local_true, &osm->y));

320:     PetscCall(ISGetLocalSize(osm->lis, &m));
321:     PetscCall(ISCreateStride(PETSC_COMM_SELF, m, 0, 1, &isl));
322:     PetscCall(MatGetVecType(osm->pmat[0], &vtype));
323:     PetscCall(VecCreate(PETSC_COMM_SELF, &osm->lx));
324:     PetscCall(VecSetSizes(osm->lx, m, m));
325:     PetscCall(VecSetType(osm->lx, vtype));
326:     PetscCall(VecDuplicate(osm->lx, &osm->ly));
327:     PetscCall(VecScatterCreate(vec, osm->lis, osm->lx, isl, &osm->restriction));
328:     PetscCall(ISDestroy(&isl));

330:     for (i = 0; i < osm->n_local_true; ++i) {
331:       ISLocalToGlobalMapping ltog;
332:       IS                     isll;
333:       const PetscInt        *idx_is;
334:       PetscInt              *idx_lis, nout;

336:       PetscCall(ISGetLocalSize(osm->is[i], &m));
337:       PetscCall(MatCreateVecs(osm->pmat[i], &osm->x[i], NULL));
338:       PetscCall(VecDuplicate(osm->x[i], &osm->y[i]));

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

360:         PetscCall(ISGetLocalSize(osm->is_local[i], &m_local));
361:         PetscCall(ISGetIndices(osm->is_local[i], &idx_local));

363:         PetscCall(ISLocalToGlobalMappingCreateIS(osm->is[i], &ltog));
364:         PetscCall(PetscMalloc1(m_local, &idx1));
365:         PetscCall(ISGlobalToLocalMappingApply(ltog, IS_GTOLM_DROP, m_local, idx_local, &nout, idx1));
366:         PetscCall(ISLocalToGlobalMappingDestroy(&ltog));
367:         PetscCheck(nout == m_local, PETSC_COMM_SELF, PETSC_ERR_PLIB, "is_local not a subset of is");
368:         PetscCall(ISCreateGeneral(PETSC_COMM_SELF, m_local, idx1, PETSC_OWN_POINTER, &isll));

370:         PetscCall(ISLocalToGlobalMappingCreateIS(osm->lis, &ltog));
371:         PetscCall(PetscMalloc1(m_local, &idx2));
372:         PetscCall(ISGlobalToLocalMappingApply(ltog, IS_GTOLM_DROP, m_local, idx_local, &nout, idx2));
373:         PetscCall(ISLocalToGlobalMappingDestroy(&ltog));
374:         PetscCheck(nout == m_local, PETSC_COMM_SELF, PETSC_ERR_PLIB, "is_local not a subset of lis");
375:         PetscCall(ISCreateGeneral(PETSC_COMM_SELF, m_local, idx2, PETSC_OWN_POINTER, &isll_local));

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

380:         PetscCall(ISDestroy(&isll));
381:         PetscCall(ISDestroy(&isll_local));
382:       }
383:     }
384:     PetscCall(VecDestroy(&vec));
385:   }

387:   if (osm->loctype == PC_COMPOSITE_MULTIPLICATIVE) {
388:     IS      *cis;
389:     PetscInt c;

391:     PetscCall(PetscMalloc1(osm->n_local_true, &cis));
392:     for (c = 0; c < osm->n_local_true; ++c) cis[c] = osm->lis;
393:     PetscCall(MatCreateSubMatrices(pc->pmat, osm->n_local_true, osm->is, cis, scall, &osm->lmats));
394:     PetscCall(PetscFree(cis));
395:   }

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

401:   /*
402:      Loop over subdomains putting them into local ksp
403:   */
404:   PetscCall(KSPGetOptionsPrefix(osm->ksp[0], &prefix));
405:   for (i = 0; i < osm->n_local_true; i++) {
406:     PetscCall(KSPSetOperators(osm->ksp[i], osm->pmat[i], osm->pmat[i]));
407:     PetscCall(MatSetOptionsPrefix(osm->pmat[i], prefix));
408:     if (!pc->setupcalled) PetscCall(KSPSetFromOptions(osm->ksp[i]));
409:   }
410:   PetscFunctionReturn(PETSC_SUCCESS);
411: }

413: static PetscErrorCode PCSetUpOnBlocks_ASM(PC pc)
414: {
415:   PC_ASM            *osm = (PC_ASM *)pc->data;
416:   PetscInt           i;
417:   KSPConvergedReason reason;

419:   PetscFunctionBegin;
420:   for (i = 0; i < osm->n_local_true; i++) {
421:     PetscCall(KSPSetUp(osm->ksp[i]));
422:     PetscCall(KSPGetConvergedReason(osm->ksp[i], &reason));
423:     if (reason == KSP_DIVERGED_PC_FAILED) pc->failedreason = PC_SUBPC_ERROR;
424:   }
425:   PetscFunctionReturn(PETSC_SUCCESS);
426: }

428: static PetscErrorCode PCApply_ASM(PC pc, Vec x, Vec y)
429: {
430:   PC_ASM     *osm = (PC_ASM *)pc->data;
431:   PetscInt    i, n_local_true = osm->n_local_true;
432:   ScatterMode forward = SCATTER_FORWARD, reverse = SCATTER_REVERSE;

434:   PetscFunctionBegin;
435:   /*
436:      support for limiting the restriction or interpolation to only local
437:      subdomain values (leaving the other values 0).
438:   */
439:   if (!(osm->type & PC_ASM_RESTRICT)) {
440:     forward = SCATTER_FORWARD_LOCAL;
441:     /* have to zero the work RHS since scatter may leave some slots empty */
442:     PetscCall(VecSet(osm->lx, 0.0));
443:   }
444:   if (!(osm->type & PC_ASM_INTERPOLATE)) reverse = SCATTER_REVERSE_LOCAL;

446:   PetscCheck(osm->loctype == PC_COMPOSITE_MULTIPLICATIVE || osm->loctype == PC_COMPOSITE_ADDITIVE, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONG, "Invalid local composition type: %s", PCCompositeTypes[osm->loctype]);
447:   /* zero the global and the local solutions */
448:   PetscCall(VecSet(y, 0.0));
449:   PetscCall(VecSet(osm->ly, 0.0));

451:   /* copy the global RHS to local RHS including the ghost nodes */
452:   PetscCall(VecScatterBegin(osm->restriction, x, osm->lx, INSERT_VALUES, forward));
453:   PetscCall(VecScatterEnd(osm->restriction, x, osm->lx, INSERT_VALUES, forward));

455:   /* restrict local RHS to the overlapping 0-block RHS */
456:   PetscCall(VecScatterBegin(osm->lrestriction[0], osm->lx, osm->x[0], INSERT_VALUES, forward));
457:   PetscCall(VecScatterEnd(osm->lrestriction[0], osm->lx, osm->x[0], INSERT_VALUES, forward));

459:   /* do the local solves */
460:   for (i = 0; i < n_local_true; ++i) {
461:     /* solve the overlapping i-block */
462:     PetscCall(PetscLogEventBegin(PC_ApplyOnBlocks, osm->ksp[i], osm->x[i], osm->y[i], 0));
463:     PetscCall(KSPSolve(osm->ksp[i], osm->x[i], osm->y[i]));
464:     PetscCall(KSPCheckSolve(osm->ksp[i], pc, osm->y[i]));
465:     PetscCall(PetscLogEventEnd(PC_ApplyOnBlocks, osm->ksp[i], osm->x[i], osm->y[i], 0));

467:     if (osm->lprolongation && osm->type != PC_ASM_INTERPOLATE) { /* interpolate the non-overlapping i-block solution to the local solution (only for restrictive additive) */
468:       PetscCall(VecScatterBegin(osm->lprolongation[i], osm->y[i], osm->ly, ADD_VALUES, forward));
469:       PetscCall(VecScatterEnd(osm->lprolongation[i], osm->y[i], osm->ly, ADD_VALUES, forward));
470:     } else { /* interpolate the overlapping i-block solution to the local solution */
471:       PetscCall(VecScatterBegin(osm->lrestriction[i], osm->y[i], osm->ly, ADD_VALUES, reverse));
472:       PetscCall(VecScatterEnd(osm->lrestriction[i], osm->y[i], osm->ly, ADD_VALUES, reverse));
473:     }

475:     if (i < n_local_true - 1) {
476:       /* restrict local RHS to the overlapping (i+1)-block RHS */
477:       PetscCall(VecScatterBegin(osm->lrestriction[i + 1], osm->lx, osm->x[i + 1], INSERT_VALUES, forward));
478:       PetscCall(VecScatterEnd(osm->lrestriction[i + 1], osm->lx, osm->x[i + 1], INSERT_VALUES, forward));

480:       if (osm->loctype == PC_COMPOSITE_MULTIPLICATIVE) {
481:         /* update the overlapping (i+1)-block RHS using the current local solution */
482:         PetscCall(MatMult(osm->lmats[i + 1], osm->ly, osm->y[i + 1]));
483:         PetscCall(VecAXPBY(osm->x[i + 1], -1., 1., osm->y[i + 1]));
484:       }
485:     }
486:   }
487:   /* add the local solution to the global solution including the ghost nodes */
488:   PetscCall(VecScatterBegin(osm->restriction, osm->ly, y, ADD_VALUES, reverse));
489:   PetscCall(VecScatterEnd(osm->restriction, osm->ly, y, ADD_VALUES, reverse));
490:   PetscFunctionReturn(PETSC_SUCCESS);
491: }

493: static PetscErrorCode PCMatApply_ASM(PC pc, Mat X, Mat Y)
494: {
495:   PC_ASM     *osm = (PC_ASM *)pc->data;
496:   Mat         Z, W;
497:   Vec         x;
498:   PetscInt    i, m, N;
499:   ScatterMode forward = SCATTER_FORWARD, reverse = SCATTER_REVERSE;

501:   PetscFunctionBegin;
502:   PetscCheck(osm->n_local_true <= 1, PetscObjectComm((PetscObject)pc), PETSC_ERR_SUP, "Not yet implemented");
503:   /*
504:      support for limiting the restriction or interpolation to only local
505:      subdomain values (leaving the other values 0).
506:   */
507:   if (!(osm->type & PC_ASM_RESTRICT)) {
508:     forward = SCATTER_FORWARD_LOCAL;
509:     /* have to zero the work RHS since scatter may leave some slots empty */
510:     PetscCall(VecSet(osm->lx, 0.0));
511:   }
512:   if (!(osm->type & PC_ASM_INTERPOLATE)) reverse = SCATTER_REVERSE_LOCAL;
513:   PetscCall(VecGetLocalSize(osm->x[0], &m));
514:   PetscCall(MatGetSize(X, NULL, &N));
515:   PetscCall(MatCreateSeqDense(PETSC_COMM_SELF, m, N, NULL, &Z));

517:   PetscCheck(osm->loctype == PC_COMPOSITE_MULTIPLICATIVE || osm->loctype == PC_COMPOSITE_ADDITIVE, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONG, "Invalid local composition type: %s", PCCompositeTypes[osm->loctype]);
518:   /* zero the global and the local solutions */
519:   PetscCall(MatZeroEntries(Y));
520:   PetscCall(VecSet(osm->ly, 0.0));

522:   for (i = 0; i < N; ++i) {
523:     PetscCall(MatDenseGetColumnVecRead(X, i, &x));
524:     /* copy the global RHS to local RHS including the ghost nodes */
525:     PetscCall(VecScatterBegin(osm->restriction, x, osm->lx, INSERT_VALUES, forward));
526:     PetscCall(VecScatterEnd(osm->restriction, x, osm->lx, INSERT_VALUES, forward));
527:     PetscCall(MatDenseRestoreColumnVecRead(X, i, &x));

529:     PetscCall(MatDenseGetColumnVecWrite(Z, i, &x));
530:     /* restrict local RHS to the overlapping 0-block RHS */
531:     PetscCall(VecScatterBegin(osm->lrestriction[0], osm->lx, x, INSERT_VALUES, forward));
532:     PetscCall(VecScatterEnd(osm->lrestriction[0], osm->lx, x, INSERT_VALUES, forward));
533:     PetscCall(MatDenseRestoreColumnVecWrite(Z, i, &x));
534:   }
535:   PetscCall(MatCreateSeqDense(PETSC_COMM_SELF, m, N, NULL, &W));
536:   /* solve the overlapping 0-block */
537:   PetscCall(PetscLogEventBegin(PC_ApplyOnBlocks, osm->ksp[0], Z, W, 0));
538:   PetscCall(KSPMatSolve(osm->ksp[0], Z, W));
539:   PetscCall(KSPCheckSolve(osm->ksp[0], pc, NULL));
540:   PetscCall(PetscLogEventEnd(PC_ApplyOnBlocks, osm->ksp[0], Z, W, 0));
541:   PetscCall(MatDestroy(&Z));

543:   for (i = 0; i < N; ++i) {
544:     PetscCall(VecSet(osm->ly, 0.0));
545:     PetscCall(MatDenseGetColumnVecRead(W, i, &x));
546:     if (osm->lprolongation && osm->type != PC_ASM_INTERPOLATE) { /* interpolate the non-overlapping 0-block solution to the local solution (only for restrictive additive) */
547:       PetscCall(VecScatterBegin(osm->lprolongation[0], x, osm->ly, ADD_VALUES, forward));
548:       PetscCall(VecScatterEnd(osm->lprolongation[0], x, osm->ly, ADD_VALUES, forward));
549:     } else { /* interpolate the overlapping 0-block solution to the local solution */
550:       PetscCall(VecScatterBegin(osm->lrestriction[0], x, osm->ly, ADD_VALUES, reverse));
551:       PetscCall(VecScatterEnd(osm->lrestriction[0], x, osm->ly, ADD_VALUES, reverse));
552:     }
553:     PetscCall(MatDenseRestoreColumnVecRead(W, i, &x));

555:     PetscCall(MatDenseGetColumnVecWrite(Y, i, &x));
556:     /* add the local solution to the global solution including the ghost nodes */
557:     PetscCall(VecScatterBegin(osm->restriction, osm->ly, x, ADD_VALUES, reverse));
558:     PetscCall(VecScatterEnd(osm->restriction, osm->ly, x, ADD_VALUES, reverse));
559:     PetscCall(MatDenseRestoreColumnVecWrite(Y, i, &x));
560:   }
561:   PetscCall(MatDestroy(&W));
562:   PetscFunctionReturn(PETSC_SUCCESS);
563: }

565: static PetscErrorCode PCApplyTranspose_ASM(PC pc, Vec x, Vec y)
566: {
567:   PC_ASM     *osm = (PC_ASM *)pc->data;
568:   PetscInt    i, n_local_true = osm->n_local_true;
569:   ScatterMode forward = SCATTER_FORWARD, reverse = SCATTER_REVERSE;

571:   PetscFunctionBegin;
572:   /*
573:      Support for limiting the restriction or interpolation to only local
574:      subdomain values (leaving the other values 0).

576:      Note: these are reversed from the PCApply_ASM() because we are applying the
577:      transpose of the three terms
578:   */

580:   if (!(osm->type & PC_ASM_INTERPOLATE)) {
581:     forward = SCATTER_FORWARD_LOCAL;
582:     /* have to zero the work RHS since scatter may leave some slots empty */
583:     PetscCall(VecSet(osm->lx, 0.0));
584:   }
585:   if (!(osm->type & PC_ASM_RESTRICT)) reverse = SCATTER_REVERSE_LOCAL;

587:   /* zero the global and the local solutions */
588:   PetscCall(VecSet(y, 0.0));
589:   PetscCall(VecSet(osm->ly, 0.0));

591:   /* Copy the global RHS to local RHS including the ghost nodes */
592:   PetscCall(VecScatterBegin(osm->restriction, x, osm->lx, INSERT_VALUES, forward));
593:   PetscCall(VecScatterEnd(osm->restriction, x, osm->lx, INSERT_VALUES, forward));

595:   /* Restrict local RHS to the overlapping 0-block RHS */
596:   PetscCall(VecScatterBegin(osm->lrestriction[0], osm->lx, osm->x[0], INSERT_VALUES, forward));
597:   PetscCall(VecScatterEnd(osm->lrestriction[0], osm->lx, osm->x[0], INSERT_VALUES, forward));

599:   /* do the local solves */
600:   for (i = 0; i < n_local_true; ++i) {
601:     /* solve the overlapping i-block */
602:     PetscCall(PetscLogEventBegin(PC_ApplyOnBlocks, osm->ksp[i], osm->x[i], osm->y[i], 0));
603:     PetscCall(KSPSolveTranspose(osm->ksp[i], osm->x[i], osm->y[i]));
604:     PetscCall(KSPCheckSolve(osm->ksp[i], pc, osm->y[i]));
605:     PetscCall(PetscLogEventEnd(PC_ApplyOnBlocks, osm->ksp[i], osm->x[i], osm->y[i], 0));

607:     if (osm->lprolongation && osm->type != PC_ASM_RESTRICT) { /* interpolate the non-overlapping i-block solution to the local solution */
608:       PetscCall(VecScatterBegin(osm->lprolongation[i], osm->y[i], osm->ly, ADD_VALUES, forward));
609:       PetscCall(VecScatterEnd(osm->lprolongation[i], osm->y[i], osm->ly, ADD_VALUES, forward));
610:     } else { /* interpolate the overlapping i-block solution to the local solution */
611:       PetscCall(VecScatterBegin(osm->lrestriction[i], osm->y[i], osm->ly, ADD_VALUES, reverse));
612:       PetscCall(VecScatterEnd(osm->lrestriction[i], osm->y[i], osm->ly, ADD_VALUES, reverse));
613:     }

615:     if (i < n_local_true - 1) {
616:       /* Restrict local RHS to the overlapping (i+1)-block RHS */
617:       PetscCall(VecScatterBegin(osm->lrestriction[i + 1], osm->lx, osm->x[i + 1], INSERT_VALUES, forward));
618:       PetscCall(VecScatterEnd(osm->lrestriction[i + 1], osm->lx, osm->x[i + 1], INSERT_VALUES, forward));
619:     }
620:   }
621:   /* Add the local solution to the global solution including the ghost nodes */
622:   PetscCall(VecScatterBegin(osm->restriction, osm->ly, y, ADD_VALUES, reverse));
623:   PetscCall(VecScatterEnd(osm->restriction, osm->ly, y, ADD_VALUES, reverse));
624:   PetscFunctionReturn(PETSC_SUCCESS);
625: }

627: static PetscErrorCode PCReset_ASM(PC pc)
628: {
629:   PC_ASM  *osm = (PC_ASM *)pc->data;
630:   PetscInt i;

632:   PetscFunctionBegin;
633:   if (osm->ksp) {
634:     for (i = 0; i < osm->n_local_true; i++) PetscCall(KSPReset(osm->ksp[i]));
635:   }
636:   if (osm->pmat) {
637:     if (osm->n_local_true > 0) PetscCall(MatDestroySubMatrices(osm->n_local_true, &osm->pmat));
638:   }
639:   if (osm->lrestriction) {
640:     PetscCall(VecScatterDestroy(&osm->restriction));
641:     for (i = 0; i < osm->n_local_true; i++) {
642:       PetscCall(VecScatterDestroy(&osm->lrestriction[i]));
643:       if (osm->lprolongation) PetscCall(VecScatterDestroy(&osm->lprolongation[i]));
644:       PetscCall(VecDestroy(&osm->x[i]));
645:       PetscCall(VecDestroy(&osm->y[i]));
646:     }
647:     PetscCall(PetscFree(osm->lrestriction));
648:     if (osm->lprolongation) PetscCall(PetscFree(osm->lprolongation));
649:     PetscCall(PetscFree(osm->x));
650:     PetscCall(PetscFree(osm->y));
651:   }
652:   PetscCall(PCASMDestroySubdomains(osm->n_local_true, osm->is, osm->is_local));
653:   PetscCall(ISDestroy(&osm->lis));
654:   PetscCall(VecDestroy(&osm->lx));
655:   PetscCall(VecDestroy(&osm->ly));
656:   if (osm->loctype == PC_COMPOSITE_MULTIPLICATIVE) PetscCall(MatDestroyMatrices(osm->n_local_true, &osm->lmats));

658:   PetscCall(PetscFree(osm->sub_mat_type));

660:   osm->is       = NULL;
661:   osm->is_local = NULL;
662:   PetscFunctionReturn(PETSC_SUCCESS);
663: }

665: static PetscErrorCode PCDestroy_ASM(PC pc)
666: {
667:   PC_ASM  *osm = (PC_ASM *)pc->data;
668:   PetscInt i;

670:   PetscFunctionBegin;
671:   PetscCall(PCReset_ASM(pc));
672:   if (osm->ksp) {
673:     for (i = 0; i < osm->n_local_true; i++) PetscCall(KSPDestroy(&osm->ksp[i]));
674:     PetscCall(PetscFree(osm->ksp));
675:   }
676:   PetscCall(PetscFree(pc->data));

678:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetLocalSubdomains_C", NULL));
679:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetTotalSubdomains_C", NULL));
680:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetOverlap_C", NULL));
681:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetType_C", NULL));
682:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMGetType_C", NULL));
683:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetLocalType_C", NULL));
684:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMGetLocalType_C", NULL));
685:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetSortIndices_C", NULL));
686:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMGetSubKSP_C", NULL));
687:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMGetSubMatType_C", NULL));
688:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetSubMatType_C", NULL));
689:   PetscFunctionReturn(PETSC_SUCCESS);
690: }

692: static PetscErrorCode PCSetFromOptions_ASM(PC pc, PetscOptionItems *PetscOptionsObject)
693: {
694:   PC_ASM         *osm = (PC_ASM *)pc->data;
695:   PetscInt        blocks, ovl;
696:   PetscBool       flg;
697:   PCASMType       asmtype;
698:   PCCompositeType loctype;
699:   char            sub_mat_type[256];

701:   PetscFunctionBegin;
702:   PetscOptionsHeadBegin(PetscOptionsObject, "Additive Schwarz options");
703:   PetscCall(PetscOptionsBool("-pc_asm_dm_subdomains", "Use DMCreateDomainDecomposition() to define subdomains", "PCASMSetDMSubdomains", osm->dm_subdomains, &osm->dm_subdomains, &flg));
704:   PetscCall(PetscOptionsInt("-pc_asm_blocks", "Number of subdomains", "PCASMSetTotalSubdomains", osm->n, &blocks, &flg));
705:   if (flg) {
706:     PetscCall(PCASMSetTotalSubdomains(pc, blocks, NULL, NULL));
707:     osm->dm_subdomains = PETSC_FALSE;
708:   }
709:   PetscCall(PetscOptionsInt("-pc_asm_local_blocks", "Number of local subdomains", "PCASMSetLocalSubdomains", osm->n_local_true, &blocks, &flg));
710:   if (flg) {
711:     PetscCall(PCASMSetLocalSubdomains(pc, blocks, NULL, NULL));
712:     osm->dm_subdomains = PETSC_FALSE;
713:   }
714:   PetscCall(PetscOptionsInt("-pc_asm_overlap", "Number of grid points overlap", "PCASMSetOverlap", osm->overlap, &ovl, &flg));
715:   if (flg) {
716:     PetscCall(PCASMSetOverlap(pc, ovl));
717:     osm->dm_subdomains = PETSC_FALSE;
718:   }
719:   flg = PETSC_FALSE;
720:   PetscCall(PetscOptionsEnum("-pc_asm_type", "Type of restriction/extension", "PCASMSetType", PCASMTypes, (PetscEnum)osm->type, (PetscEnum *)&asmtype, &flg));
721:   if (flg) PetscCall(PCASMSetType(pc, asmtype));
722:   flg = PETSC_FALSE;
723:   PetscCall(PetscOptionsEnum("-pc_asm_local_type", "Type of local solver composition", "PCASMSetLocalType", PCCompositeTypes, (PetscEnum)osm->loctype, (PetscEnum *)&loctype, &flg));
724:   if (flg) PetscCall(PCASMSetLocalType(pc, loctype));
725:   PetscCall(PetscOptionsFList("-pc_asm_sub_mat_type", "Subsolve Matrix Type", "PCASMSetSubMatType", MatList, NULL, sub_mat_type, 256, &flg));
726:   if (flg) PetscCall(PCASMSetSubMatType(pc, sub_mat_type));
727:   PetscOptionsHeadEnd();
728:   PetscFunctionReturn(PETSC_SUCCESS);
729: }

731: static PetscErrorCode PCASMSetLocalSubdomains_ASM(PC pc, PetscInt n, IS is[], IS is_local[])
732: {
733:   PC_ASM  *osm = (PC_ASM *)pc->data;
734:   PetscInt i;

736:   PetscFunctionBegin;
737:   PetscCheck(n >= 1, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Each process must have 1 or more blocks, n = %" PetscInt_FMT, n);
738:   PetscCheck(!pc->setupcalled || (n == osm->n_local_true && !is), PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONGSTATE, "PCASMSetLocalSubdomains() should be called before calling PCSetUp().");

740:   if (!pc->setupcalled) {
741:     if (is) {
742:       for (i = 0; i < n; i++) PetscCall(PetscObjectReference((PetscObject)is[i]));
743:     }
744:     if (is_local) {
745:       for (i = 0; i < n; i++) PetscCall(PetscObjectReference((PetscObject)is_local[i]));
746:     }
747:     PetscCall(PCASMDestroySubdomains(osm->n_local_true, osm->is, osm->is_local));

749:     if (osm->ksp && osm->n_local_true != n) {
750:       for (i = 0; i < osm->n_local_true; i++) PetscCall(KSPDestroy(&osm->ksp[i]));
751:       PetscCall(PetscFree(osm->ksp));
752:     }

754:     osm->n_local_true = n;
755:     osm->is           = NULL;
756:     osm->is_local     = NULL;
757:     if (is) {
758:       PetscCall(PetscMalloc1(n, &osm->is));
759:       for (i = 0; i < n; i++) osm->is[i] = is[i];
760:       /* Flag indicating that the user has set overlapping subdomains so PCASM should not increase their size. */
761:       osm->overlap = -1;
762:     }
763:     if (is_local) {
764:       PetscCall(PetscMalloc1(n, &osm->is_local));
765:       for (i = 0; i < n; i++) osm->is_local[i] = is_local[i];
766:       if (!is) {
767:         PetscCall(PetscMalloc1(osm->n_local_true, &osm->is));
768:         for (i = 0; i < osm->n_local_true; i++) {
769:           if (osm->overlap > 0) { /* With positive overlap, osm->is[i] will be modified */
770:             PetscCall(ISDuplicate(osm->is_local[i], &osm->is[i]));
771:             PetscCall(ISCopy(osm->is_local[i], osm->is[i]));
772:           } else {
773:             PetscCall(PetscObjectReference((PetscObject)osm->is_local[i]));
774:             osm->is[i] = osm->is_local[i];
775:           }
776:         }
777:       }
778:     }
779:   }
780:   PetscFunctionReturn(PETSC_SUCCESS);
781: }

783: static PetscErrorCode PCASMSetTotalSubdomains_ASM(PC pc, PetscInt N, IS *is, IS *is_local)
784: {
785:   PC_ASM     *osm = (PC_ASM *)pc->data;
786:   PetscMPIInt rank, size;
787:   PetscInt    n;

789:   PetscFunctionBegin;
790:   PetscCheck(N >= 1, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_OUTOFRANGE, "Number of total blocks must be > 0, N = %" PetscInt_FMT, N);
791:   PetscCheck(!is && !is_local, PetscObjectComm((PetscObject)pc), PETSC_ERR_SUP, "Use PCASMSetLocalSubdomains() to set specific index sets, they cannot be set globally yet.");

793:   /*
794:      Split the subdomains equally among all processors
795:   */
796:   PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)pc), &rank));
797:   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)pc), &size));
798:   n = N / size + ((N % size) > rank);
799:   PetscCheck(n, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Process %d must have at least one block: total processors %d total blocks %" PetscInt_FMT, rank, size, N);
800:   PetscCheck(!pc->setupcalled || n == osm->n_local_true, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "PCASMSetTotalSubdomains() should be called before PCSetUp().");
801:   if (!pc->setupcalled) {
802:     PetscCall(PCASMDestroySubdomains(osm->n_local_true, osm->is, osm->is_local));

804:     osm->n_local_true = n;
805:     osm->is           = NULL;
806:     osm->is_local     = NULL;
807:   }
808:   PetscFunctionReturn(PETSC_SUCCESS);
809: }

811: static PetscErrorCode PCASMSetOverlap_ASM(PC pc, PetscInt ovl)
812: {
813:   PC_ASM *osm = (PC_ASM *)pc->data;

815:   PetscFunctionBegin;
816:   PetscCheck(ovl >= 0, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_OUTOFRANGE, "Negative overlap value requested");
817:   PetscCheck(!pc->setupcalled || ovl == osm->overlap, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONGSTATE, "PCASMSetOverlap() should be called before PCSetUp().");
818:   if (!pc->setupcalled) osm->overlap = ovl;
819:   PetscFunctionReturn(PETSC_SUCCESS);
820: }

822: static PetscErrorCode PCASMSetType_ASM(PC pc, PCASMType type)
823: {
824:   PC_ASM *osm = (PC_ASM *)pc->data;

826:   PetscFunctionBegin;
827:   osm->type     = type;
828:   osm->type_set = PETSC_TRUE;
829:   PetscFunctionReturn(PETSC_SUCCESS);
830: }

832: static PetscErrorCode PCASMGetType_ASM(PC pc, PCASMType *type)
833: {
834:   PC_ASM *osm = (PC_ASM *)pc->data;

836:   PetscFunctionBegin;
837:   *type = osm->type;
838:   PetscFunctionReturn(PETSC_SUCCESS);
839: }

841: static PetscErrorCode PCASMSetLocalType_ASM(PC pc, PCCompositeType type)
842: {
843:   PC_ASM *osm = (PC_ASM *)pc->data;

845:   PetscFunctionBegin;
846:   PetscCheck(type == PC_COMPOSITE_ADDITIVE || type == PC_COMPOSITE_MULTIPLICATIVE, PetscObjectComm((PetscObject)pc), PETSC_ERR_SUP, "Only supports additive or multiplicative as the local type");
847:   osm->loctype = type;
848:   PetscFunctionReturn(PETSC_SUCCESS);
849: }

851: static PetscErrorCode PCASMGetLocalType_ASM(PC pc, PCCompositeType *type)
852: {
853:   PC_ASM *osm = (PC_ASM *)pc->data;

855:   PetscFunctionBegin;
856:   *type = osm->loctype;
857:   PetscFunctionReturn(PETSC_SUCCESS);
858: }

860: static PetscErrorCode PCASMSetSortIndices_ASM(PC pc, PetscBool doSort)
861: {
862:   PC_ASM *osm = (PC_ASM *)pc->data;

864:   PetscFunctionBegin;
865:   osm->sort_indices = doSort;
866:   PetscFunctionReturn(PETSC_SUCCESS);
867: }

869: static PetscErrorCode PCASMGetSubKSP_ASM(PC pc, PetscInt *n_local, PetscInt *first_local, KSP **ksp)
870: {
871:   PC_ASM *osm = (PC_ASM *)pc->data;

873:   PetscFunctionBegin;
874:   PetscCheck(osm->n_local_true >= 1, PetscObjectComm((PetscObject)pc), PETSC_ERR_ORDER, "Need to call PCSetUp() on PC (or KSPSetUp() on the outer KSP object) before calling here");

876:   if (n_local) *n_local = osm->n_local_true;
877:   if (first_local) {
878:     PetscCallMPI(MPI_Scan(&osm->n_local_true, first_local, 1, MPIU_INT, MPI_SUM, PetscObjectComm((PetscObject)pc)));
879:     *first_local -= osm->n_local_true;
880:   }
881:   if (ksp) *ksp = osm->ksp;
882:   PetscFunctionReturn(PETSC_SUCCESS);
883: }

885: static PetscErrorCode PCASMGetSubMatType_ASM(PC pc, MatType *sub_mat_type)
886: {
887:   PC_ASM *osm = (PC_ASM *)pc->data;

889:   PetscFunctionBegin;
891:   PetscAssertPointer(sub_mat_type, 2);
892:   *sub_mat_type = osm->sub_mat_type;
893:   PetscFunctionReturn(PETSC_SUCCESS);
894: }

896: static PetscErrorCode PCASMSetSubMatType_ASM(PC pc, MatType sub_mat_type)
897: {
898:   PC_ASM *osm = (PC_ASM *)pc->data;

900:   PetscFunctionBegin;
902:   PetscCall(PetscFree(osm->sub_mat_type));
903:   PetscCall(PetscStrallocpy(sub_mat_type, (char **)&osm->sub_mat_type));
904:   PetscFunctionReturn(PETSC_SUCCESS);
905: }

907: /*@
908:   PCASMSetLocalSubdomains - Sets the local subdomains (for this processor only) for the additive Schwarz preconditioner `PCASM`.

910:   Collective

912:   Input Parameters:
913: + pc       - the preconditioner context
914: . n        - the number of subdomains for this processor (default value = 1)
915: . is       - the index set that defines the subdomains for this processor (or `NULL` for PETSc to determine subdomains)
916:              the values of the `is` array are copied so you can free the array (not the `IS` in the array) after this call
917: - is_local - the index sets that define the local part of the subdomains for this processor, not used unless `PCASMType` is `PC_ASM_RESTRICT`
918:              (or `NULL` to not provide these). The values of the `is_local` array are copied so you can free the array
919:              (not the `IS` in the array) after this call

921:   Options Database Key:
922: . -pc_asm_local_blocks <blks> - Sets number of local blocks

924:   Level: advanced

926:   Notes:
927:   The `IS` numbering is in the parallel, global numbering of the vector for both `is` and `is_local`

929:   By default the `PCASM` preconditioner uses 1 block per processor.

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

933:   If `is_local` is provided and `PCASMType` is `PC_ASM_RESTRICT` then the solution only over the `is_local` region is interpolated
934:   back to form the global solution (this is the standard restricted additive Schwarz method, RASM)

936:   If `is_local` is provided and `PCASMType` is `PC_ASM_INTERPOLATE` or `PC_ASM_NONE` then an error is generated since there is
937:   no code to handle that case.

939: .seealso: [](ch_ksp), `PCASM`, `PCASMSetTotalSubdomains()`, `PCASMSetOverlap()`, `PCASMGetSubKSP()`,
940:           `PCASMCreateSubdomains2D()`, `PCASMGetLocalSubdomains()`, `PCASMType`, `PCASMSetType()`, `PCGASM`
941: @*/
942: PetscErrorCode PCASMSetLocalSubdomains(PC pc, PetscInt n, IS is[], IS is_local[])
943: {
944:   PetscFunctionBegin;
946:   PetscTryMethod(pc, "PCASMSetLocalSubdomains_C", (PC, PetscInt, IS[], IS[]), (pc, n, is, is_local));
947:   PetscFunctionReturn(PETSC_SUCCESS);
948: }

950: /*@
951:   PCASMSetTotalSubdomains - Sets the subdomains for all processors for the
952:   additive Schwarz preconditioner, `PCASM`.

954:   Collective, all MPI ranks must pass in the same array of `IS`

956:   Input Parameters:
957: + pc       - the preconditioner context
958: . N        - the number of subdomains for all processors
959: . is       - the index sets that define the subdomains for all processors (or `NULL` to ask PETSc to determine the subdomains)
960:              the values of the `is` array are copied so you can free the array (not the `IS` in the array) after this call
961: - is_local - the index sets that define the local part of the subdomains for this processor (or `NULL` to not provide this information)
962:              The values of the `is_local` array are copied so you can free the array (not the `IS` in the array) after this call

964:   Options Database Key:
965: . -pc_asm_blocks <blks> - Sets total blocks

967:   Level: advanced

969:   Notes:
970:   Currently you cannot use this to set the actual subdomains with the argument `is` or `is_local`.

972:   By default the `PCASM` preconditioner uses 1 block per processor.

974:   These index sets cannot be destroyed until after completion of the
975:   linear solves for which the `PCASM` preconditioner is being used.

977:   Use `PCASMSetLocalSubdomains()` to set local subdomains.

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

981: .seealso: [](ch_ksp), `PCASM`, `PCASMSetLocalSubdomains()`, `PCASMSetOverlap()`, `PCASMGetSubKSP()`,
982:           `PCASMCreateSubdomains2D()`, `PCGASM`
983: @*/
984: PetscErrorCode PCASMSetTotalSubdomains(PC pc, PetscInt N, IS is[], IS is_local[])
985: {
986:   PetscFunctionBegin;
988:   PetscTryMethod(pc, "PCASMSetTotalSubdomains_C", (PC, PetscInt, IS[], IS[]), (pc, N, is, is_local));
989:   PetscFunctionReturn(PETSC_SUCCESS);
990: }

992: /*@
993:   PCASMSetOverlap - Sets the overlap between a pair of subdomains for the
994:   additive Schwarz preconditioner, `PCASM`.

996:   Logically Collective

998:   Input Parameters:
999: + pc  - the preconditioner context
1000: - ovl - the amount of overlap between subdomains (ovl >= 0, default value = 1)

1002:   Options Database Key:
1003: . -pc_asm_overlap <ovl> - Sets overlap

1005:   Level: intermediate

1007:   Notes:
1008:   By default the `PCASM` preconditioner uses 1 block per processor.  To use
1009:   multiple blocks per perocessor, see `PCASMSetTotalSubdomains()` and
1010:   `PCASMSetLocalSubdomains()` (and the option -pc_asm_blocks <blks>).

1012:   The overlap defaults to 1, so if one desires that no additional
1013:   overlap be computed beyond what may have been set with a call to
1014:   `PCASMSetTotalSubdomains()` or `PCASMSetLocalSubdomains()`, then ovl
1015:   must be set to be 0.  In particular, if one does not explicitly set
1016:   the subdomains an application code, then all overlap would be computed
1017:   internally by PETSc, and using an overlap of 0 would result in an `PCASM`
1018:   variant that is equivalent to the block Jacobi preconditioner.

1020:   The default algorithm used by PETSc to increase overlap is fast, but not scalable,
1021:   use the option -mat_increase_overlap_scalable when the problem and number of processes is large.

1023:   One can define initial index sets with any overlap via
1024:   `PCASMSetLocalSubdomains()`; the routine
1025:   `PCASMSetOverlap()` merely allows PETSc to extend that overlap further
1026:   if desired.

1028: .seealso: [](ch_ksp), `PCASM`, `PCASMSetTotalSubdomains()`, `PCASMSetLocalSubdomains()`, `PCASMGetSubKSP()`,
1029:           `PCASMCreateSubdomains2D()`, `PCASMGetLocalSubdomains()`, `MatIncreaseOverlap()`, `PCGASM`
1030: @*/
1031: PetscErrorCode PCASMSetOverlap(PC pc, PetscInt ovl)
1032: {
1033:   PetscFunctionBegin;
1036:   PetscTryMethod(pc, "PCASMSetOverlap_C", (PC, PetscInt), (pc, ovl));
1037:   PetscFunctionReturn(PETSC_SUCCESS);
1038: }

1040: /*@
1041:   PCASMSetType - Sets the type of restriction and interpolation used
1042:   for local problems in the additive Schwarz method, `PCASM`.

1044:   Logically Collective

1046:   Input Parameters:
1047: + pc   - the preconditioner context
1048: - type - variant of `PCASM`, one of
1049: .vb
1050:       PC_ASM_BASIC       - full interpolation and restriction
1051:       PC_ASM_RESTRICT    - full restriction, local processor interpolation (default)
1052:       PC_ASM_INTERPOLATE - full interpolation, local processor restriction
1053:       PC_ASM_NONE        - local processor restriction and interpolation
1054: .ve

1056:   Options Database Key:
1057: . -pc_asm_type [basic,restrict,interpolate,none] - Sets `PCASMType`

1059:   Level: intermediate

1061:   Note:
1062:   if the is_local arguments are passed to `PCASMSetLocalSubdomains()` then they are used when `PC_ASM_RESTRICT` has been selected
1063:   to limit the local processor interpolation

1065: .seealso: [](ch_ksp), `PCASM`, `PCASMSetTotalSubdomains()`, `PCASMGetSubKSP()`,
1066:           `PCASMCreateSubdomains2D()`, `PCASMType`, `PCASMSetLocalType()`, `PCASMGetLocalType()`, `PCGASM`
1067: @*/
1068: PetscErrorCode PCASMSetType(PC pc, PCASMType type)
1069: {
1070:   PetscFunctionBegin;
1073:   PetscTryMethod(pc, "PCASMSetType_C", (PC, PCASMType), (pc, type));
1074:   PetscFunctionReturn(PETSC_SUCCESS);
1075: }

1077: /*@
1078:   PCASMGetType - Gets the type of restriction and interpolation used
1079:   for local problems in the additive Schwarz method, `PCASM`.

1081:   Logically Collective

1083:   Input Parameter:
1084: . pc - the preconditioner context

1086:   Output Parameter:
1087: . type - variant of `PCASM`, one of
1088: .vb
1089:       PC_ASM_BASIC       - full interpolation and restriction
1090:       PC_ASM_RESTRICT    - full restriction, local processor interpolation
1091:       PC_ASM_INTERPOLATE - full interpolation, local processor restriction
1092:       PC_ASM_NONE        - local processor restriction and interpolation
1093: .ve

1095:   Options Database Key:
1096: . -pc_asm_type [basic,restrict,interpolate,none] - Sets `PCASM` type

1098:   Level: intermediate

1100: .seealso: [](ch_ksp), `PCASM`, `PCASMSetTotalSubdomains()`, `PCASMGetSubKSP()`, `PCGASM`,
1101:           `PCASMCreateSubdomains2D()`, `PCASMType`, `PCASMSetType()`, `PCASMSetLocalType()`, `PCASMGetLocalType()`
1102: @*/
1103: PetscErrorCode PCASMGetType(PC pc, PCASMType *type)
1104: {
1105:   PetscFunctionBegin;
1107:   PetscUseMethod(pc, "PCASMGetType_C", (PC, PCASMType *), (pc, type));
1108:   PetscFunctionReturn(PETSC_SUCCESS);
1109: }

1111: /*@
1112:   PCASMSetLocalType - Sets the type of composition used for local problems in the additive Schwarz method, `PCASM`.

1114:   Logically Collective

1116:   Input Parameters:
1117: + pc   - the preconditioner context
1118: - type - type of composition, one of
1119: .vb
1120:   PC_COMPOSITE_ADDITIVE       - local additive combination
1121:   PC_COMPOSITE_MULTIPLICATIVE - local multiplicative combination
1122: .ve

1124:   Options Database Key:
1125: . -pc_asm_local_type [additive,multiplicative] - Sets local solver composition type

1127:   Level: intermediate

1129: .seealso: [](ch_ksp), `PCASM`, `PCASMSetType()`, `PCASMGetType()`, `PCASMGetLocalType()`, `PCASMType`, `PCCompositeType`
1130: @*/
1131: PetscErrorCode PCASMSetLocalType(PC pc, PCCompositeType type)
1132: {
1133:   PetscFunctionBegin;
1136:   PetscTryMethod(pc, "PCASMSetLocalType_C", (PC, PCCompositeType), (pc, type));
1137:   PetscFunctionReturn(PETSC_SUCCESS);
1138: }

1140: /*@
1141:   PCASMGetLocalType - Gets the type of composition used for local problems in the additive Schwarz method, `PCASM`.

1143:   Logically Collective

1145:   Input Parameter:
1146: . pc - the preconditioner context

1148:   Output Parameter:
1149: . type - type of composition, one of
1150: .vb
1151:   PC_COMPOSITE_ADDITIVE       - local additive combination
1152:   PC_COMPOSITE_MULTIPLICATIVE - local multiplicative combination
1153: .ve

1155:   Options Database Key:
1156: . -pc_asm_local_type [additive,multiplicative] - Sets local solver composition type

1158:   Level: intermediate

1160: .seealso: [](ch_ksp), `PCASM`, `PCASMSetType()`, `PCASMGetType()`, `PCASMSetLocalType()`, `PCASMType`, `PCCompositeType`
1161: @*/
1162: PetscErrorCode PCASMGetLocalType(PC pc, PCCompositeType *type)
1163: {
1164:   PetscFunctionBegin;
1166:   PetscAssertPointer(type, 2);
1167:   PetscUseMethod(pc, "PCASMGetLocalType_C", (PC, PCCompositeType *), (pc, type));
1168:   PetscFunctionReturn(PETSC_SUCCESS);
1169: }

1171: /*@
1172:   PCASMSetSortIndices - Determines whether subdomain indices are sorted.

1174:   Logically Collective

1176:   Input Parameters:
1177: + pc     - the preconditioner context
1178: - doSort - sort the subdomain indices

1180:   Level: intermediate

1182: .seealso: [](ch_ksp), `PCASM`, `PCASMSetLocalSubdomains()`, `PCASMSetTotalSubdomains()`, `PCASMGetSubKSP()`,
1183:           `PCASMCreateSubdomains2D()`
1184: @*/
1185: PetscErrorCode PCASMSetSortIndices(PC pc, PetscBool doSort)
1186: {
1187:   PetscFunctionBegin;
1190:   PetscTryMethod(pc, "PCASMSetSortIndices_C", (PC, PetscBool), (pc, doSort));
1191:   PetscFunctionReturn(PETSC_SUCCESS);
1192: }

1194: /*@C
1195:   PCASMGetSubKSP - Gets the local `KSP` contexts for all blocks on
1196:   this processor.

1198:   Collective iff first_local is requested

1200:   Input Parameter:
1201: . pc - the preconditioner context

1203:   Output Parameters:
1204: + n_local     - the number of blocks on this processor or `NULL`
1205: . first_local - the global number of the first block on this processor or `NULL`, all processors must request or all must pass `NULL`
1206: - ksp         - the array of `KSP` contexts

1208:   Level: advanced

1210:   Notes:
1211:   After `PCASMGetSubKSP()` the array of `KSP`s is not to be freed.

1213:   You must call `KSPSetUp()` before calling `PCASMGetSubKSP()`.

1215:   Fortran Notes:
1216:   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.

1218: .seealso: [](ch_ksp), `PCASM`, `PCASMSetTotalSubdomains()`, `PCASMSetOverlap()`,
1219:           `PCASMCreateSubdomains2D()`,
1220: @*/
1221: PetscErrorCode PCASMGetSubKSP(PC pc, PetscInt *n_local, PetscInt *first_local, KSP *ksp[])
1222: {
1223:   PetscFunctionBegin;
1225:   PetscUseMethod(pc, "PCASMGetSubKSP_C", (PC, PetscInt *, PetscInt *, KSP **), (pc, n_local, first_local, ksp));
1226:   PetscFunctionReturn(PETSC_SUCCESS);
1227: }

1229: /*MC
1230:    PCASM - Use the (restricted) additive Schwarz method, each block is (approximately) solved with
1231:            its own `KSP` object, {cite}`dryja1987additive` and {cite}`1sbg`

1233:    Options Database Keys:
1234: +  -pc_asm_blocks <blks>                          - Sets total blocks. Defaults to one block per MPI process.
1235: .  -pc_asm_overlap <ovl>                          - Sets overlap
1236: .  -pc_asm_type [basic,restrict,interpolate,none] - Sets `PCASMType`, default is restrict. See `PCASMSetType()`
1237: .  -pc_asm_dm_subdomains <bool>                   - use subdomains defined by the `DM` with `DMCreateDomainDecomposition()`
1238: -  -pc_asm_local_type [additive, multiplicative]  - Sets `PCCompositeType`, default is additive. See `PCASMSetLocalType()`

1240:    Level: beginner

1242:    Notes:
1243:    If you run with, for example, 3 blocks on 1 processor or 3 blocks on 3 processors you
1244:    will get a different convergence rate due to the default option of `-pc_asm_type restrict`. Use
1245:    `-pc_asm_type basic` to get the same convergence behavior

1247:    Each processor can have one or more blocks, but a block cannot be shared by more
1248:    than one processor. Use `PCGASM` for subdomains shared by multiple processes.

1250:    To set options on the solvers for each block append `-sub_` to all the `KSP`, and `PC`
1251:    options database keys. For example, `-sub_pc_type ilu -sub_pc_factor_levels 1 -sub_ksp_type preonly`

1253:    To set the options on the solvers separate for each block call `PCASMGetSubKSP()`
1254:    and set the options directly on the resulting `KSP` object (you can access its `PC` with `KSPGetPC()`)

1256:    If the `PC` has an associated `DM`, then, by default, `DMCreateDomainDecomposition()` is used to create the subdomains

1258: .seealso: [](ch_ksp), `PCCreate()`, `PCSetType()`, `PCType`, `PC`, `PCASMType`, `PCCompositeType`,
1259:           `PCBJACOBI`, `PCASMGetSubKSP()`, `PCASMSetLocalSubdomains()`, `PCASMType`, `PCASMGetType()`, `PCASMSetLocalType()`, `PCASMGetLocalType()`
1260:           `PCASMSetTotalSubdomains()`, `PCSetModifySubMatrices()`, `PCASMSetOverlap()`, `PCASMSetType()`, `PCCompositeType`
1261: M*/

1263: PETSC_EXTERN PetscErrorCode PCCreate_ASM(PC pc)
1264: {
1265:   PC_ASM *osm;

1267:   PetscFunctionBegin;
1268:   PetscCall(PetscNew(&osm));

1270:   osm->n             = PETSC_DECIDE;
1271:   osm->n_local       = 0;
1272:   osm->n_local_true  = PETSC_DECIDE;
1273:   osm->overlap       = 1;
1274:   osm->ksp           = NULL;
1275:   osm->restriction   = NULL;
1276:   osm->lprolongation = NULL;
1277:   osm->lrestriction  = NULL;
1278:   osm->x             = NULL;
1279:   osm->y             = NULL;
1280:   osm->is            = NULL;
1281:   osm->is_local      = NULL;
1282:   osm->mat           = NULL;
1283:   osm->pmat          = NULL;
1284:   osm->type          = PC_ASM_RESTRICT;
1285:   osm->loctype       = PC_COMPOSITE_ADDITIVE;
1286:   osm->sort_indices  = PETSC_TRUE;
1287:   osm->dm_subdomains = PETSC_FALSE;
1288:   osm->sub_mat_type  = NULL;

1290:   pc->data                 = (void *)osm;
1291:   pc->ops->apply           = PCApply_ASM;
1292:   pc->ops->matapply        = PCMatApply_ASM;
1293:   pc->ops->applytranspose  = PCApplyTranspose_ASM;
1294:   pc->ops->setup           = PCSetUp_ASM;
1295:   pc->ops->reset           = PCReset_ASM;
1296:   pc->ops->destroy         = PCDestroy_ASM;
1297:   pc->ops->setfromoptions  = PCSetFromOptions_ASM;
1298:   pc->ops->setuponblocks   = PCSetUpOnBlocks_ASM;
1299:   pc->ops->view            = PCView_ASM;
1300:   pc->ops->applyrichardson = NULL;

1302:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetLocalSubdomains_C", PCASMSetLocalSubdomains_ASM));
1303:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetTotalSubdomains_C", PCASMSetTotalSubdomains_ASM));
1304:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetOverlap_C", PCASMSetOverlap_ASM));
1305:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetType_C", PCASMSetType_ASM));
1306:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMGetType_C", PCASMGetType_ASM));
1307:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetLocalType_C", PCASMSetLocalType_ASM));
1308:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMGetLocalType_C", PCASMGetLocalType_ASM));
1309:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetSortIndices_C", PCASMSetSortIndices_ASM));
1310:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMGetSubKSP_C", PCASMGetSubKSP_ASM));
1311:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMGetSubMatType_C", PCASMGetSubMatType_ASM));
1312:   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCASMSetSubMatType_C", PCASMSetSubMatType_ASM));
1313:   PetscFunctionReturn(PETSC_SUCCESS);
1314: }

1316: /*@C
1317:   PCASMCreateSubdomains - Creates the index sets for the overlapping Schwarz
1318:   preconditioner, `PCASM`,  for any problem on a general grid.

1320:   Collective

1322:   Input Parameters:
1323: + A - The global matrix operator
1324: - n - the number of local blocks

1326:   Output Parameter:
1327: . outis - the array of index sets defining the subdomains

1329:   Level: advanced

1331:   Note:
1332:   This generates nonoverlapping subdomains; the `PCASM` will generate the overlap
1333:   from these if you use `PCASMSetLocalSubdomains()`

1335:   Fortran Notes:
1336:   You must provide the array `outis` already allocated of length `n`.

1338: .seealso: [](ch_ksp), `PCASM`, `PCASMSetLocalSubdomains()`, `PCASMDestroySubdomains()`
1339: @*/
1340: PetscErrorCode PCASMCreateSubdomains(Mat A, PetscInt n, IS *outis[])
1341: {
1342:   MatPartitioning mpart;
1343:   const char     *prefix;
1344:   PetscInt        i, j, rstart, rend, bs;
1345:   PetscBool       hasop, isbaij = PETSC_FALSE, foundpart = PETSC_FALSE;
1346:   Mat             Ad = NULL, adj;
1347:   IS              ispart, isnumb, *is;

1349:   PetscFunctionBegin;
1351:   PetscAssertPointer(outis, 3);
1352:   PetscCheck(n >= 1, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "number of local blocks must be > 0, n = %" PetscInt_FMT, n);

1354:   /* Get prefix, row distribution, and block size */
1355:   PetscCall(MatGetOptionsPrefix(A, &prefix));
1356:   PetscCall(MatGetOwnershipRange(A, &rstart, &rend));
1357:   PetscCall(MatGetBlockSize(A, &bs));
1358:   PetscCheck(rstart / bs * bs == rstart && rend / bs * bs == rend, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "bad row distribution [%" PetscInt_FMT ",%" PetscInt_FMT ") for matrix block size %" PetscInt_FMT, rstart, rend, bs);

1360:   /* Get diagonal block from matrix if possible */
1361:   PetscCall(MatHasOperation(A, MATOP_GET_DIAGONAL_BLOCK, &hasop));
1362:   if (hasop) PetscCall(MatGetDiagonalBlock(A, &Ad));
1363:   if (Ad) {
1364:     PetscCall(PetscObjectBaseTypeCompare((PetscObject)Ad, MATSEQBAIJ, &isbaij));
1365:     if (!isbaij) PetscCall(PetscObjectBaseTypeCompare((PetscObject)Ad, MATSEQSBAIJ, &isbaij));
1366:   }
1367:   if (Ad && n > 1) {
1368:     PetscBool match, done;
1369:     /* Try to setup a good matrix partitioning if available */
1370:     PetscCall(MatPartitioningCreate(PETSC_COMM_SELF, &mpart));
1371:     PetscCall(PetscObjectSetOptionsPrefix((PetscObject)mpart, prefix));
1372:     PetscCall(MatPartitioningSetFromOptions(mpart));
1373:     PetscCall(PetscObjectTypeCompare((PetscObject)mpart, MATPARTITIONINGCURRENT, &match));
1374:     if (!match) PetscCall(PetscObjectTypeCompare((PetscObject)mpart, MATPARTITIONINGSQUARE, &match));
1375:     if (!match) { /* assume a "good" partitioner is available */
1376:       PetscInt        na;
1377:       const PetscInt *ia, *ja;
1378:       PetscCall(MatGetRowIJ(Ad, 0, PETSC_TRUE, isbaij, &na, &ia, &ja, &done));
1379:       if (done) {
1380:         /* Build adjacency matrix by hand. Unfortunately a call to
1381:            MatConvert(Ad,MATMPIADJ,MAT_INITIAL_MATRIX,&adj) will
1382:            remove the block-aij structure and we cannot expect
1383:            MatPartitioning to split vertices as we need */
1384:         PetscInt        i, j, len, nnz, cnt, *iia = NULL, *jja = NULL;
1385:         const PetscInt *row;
1386:         nnz = 0;
1387:         for (i = 0; i < na; i++) { /* count number of nonzeros */
1388:           len = ia[i + 1] - ia[i];
1389:           row = ja + ia[i];
1390:           for (j = 0; j < len; j++) {
1391:             if (row[j] == i) { /* don't count diagonal */
1392:               len--;
1393:               break;
1394:             }
1395:           }
1396:           nnz += len;
1397:         }
1398:         PetscCall(PetscMalloc1(na + 1, &iia));
1399:         PetscCall(PetscMalloc1(nnz, &jja));
1400:         nnz    = 0;
1401:         iia[0] = 0;
1402:         for (i = 0; i < na; i++) { /* fill adjacency */
1403:           cnt = 0;
1404:           len = ia[i + 1] - ia[i];
1405:           row = ja + ia[i];
1406:           for (j = 0; j < len; j++) {
1407:             if (row[j] != i) { /* if not diagonal */
1408:               jja[nnz + cnt++] = row[j];
1409:             }
1410:           }
1411:           nnz += cnt;
1412:           iia[i + 1] = nnz;
1413:         }
1414:         /* Partitioning of the adjacency matrix */
1415:         PetscCall(MatCreateMPIAdj(PETSC_COMM_SELF, na, na, iia, jja, NULL, &adj));
1416:         PetscCall(MatPartitioningSetAdjacency(mpart, adj));
1417:         PetscCall(MatPartitioningSetNParts(mpart, n));
1418:         PetscCall(MatPartitioningApply(mpart, &ispart));
1419:         PetscCall(ISPartitioningToNumbering(ispart, &isnumb));
1420:         PetscCall(MatDestroy(&adj));
1421:         foundpart = PETSC_TRUE;
1422:       }
1423:       PetscCall(MatRestoreRowIJ(Ad, 0, PETSC_TRUE, isbaij, &na, &ia, &ja, &done));
1424:     }
1425:     PetscCall(MatPartitioningDestroy(&mpart));
1426:   }

1428:   PetscCall(PetscMalloc1(n, &is));
1429:   *outis = is;

1431:   if (!foundpart) {
1432:     /* Partitioning by contiguous chunks of rows */

1434:     PetscInt mbs   = (rend - rstart) / bs;
1435:     PetscInt start = rstart;
1436:     for (i = 0; i < n; i++) {
1437:       PetscInt count = (mbs / n + ((mbs % n) > i)) * bs;
1438:       PetscCall(ISCreateStride(PETSC_COMM_SELF, count, start, 1, &is[i]));
1439:       start += count;
1440:     }

1442:   } else {
1443:     /* Partitioning by adjacency of diagonal block  */

1445:     const PetscInt *numbering;
1446:     PetscInt       *count, nidx, *indices, *newidx, start = 0;
1447:     /* Get node count in each partition */
1448:     PetscCall(PetscMalloc1(n, &count));
1449:     PetscCall(ISPartitioningCount(ispart, n, count));
1450:     if (isbaij && bs > 1) { /* adjust for the block-aij case */
1451:       for (i = 0; i < n; i++) count[i] *= bs;
1452:     }
1453:     /* Build indices from node numbering */
1454:     PetscCall(ISGetLocalSize(isnumb, &nidx));
1455:     PetscCall(PetscMalloc1(nidx, &indices));
1456:     for (i = 0; i < nidx; i++) indices[i] = i; /* needs to be initialized */
1457:     PetscCall(ISGetIndices(isnumb, &numbering));
1458:     PetscCall(PetscSortIntWithPermutation(nidx, numbering, indices));
1459:     PetscCall(ISRestoreIndices(isnumb, &numbering));
1460:     if (isbaij && bs > 1) { /* adjust for the block-aij case */
1461:       PetscCall(PetscMalloc1(nidx * bs, &newidx));
1462:       for (i = 0; i < nidx; i++) {
1463:         for (j = 0; j < bs; j++) newidx[i * bs + j] = indices[i] * bs + j;
1464:       }
1465:       PetscCall(PetscFree(indices));
1466:       nidx *= bs;
1467:       indices = newidx;
1468:     }
1469:     /* Shift to get global indices */
1470:     for (i = 0; i < nidx; i++) indices[i] += rstart;

1472:     /* Build the index sets for each block */
1473:     for (i = 0; i < n; i++) {
1474:       PetscCall(ISCreateGeneral(PETSC_COMM_SELF, count[i], &indices[start], PETSC_COPY_VALUES, &is[i]));
1475:       PetscCall(ISSort(is[i]));
1476:       start += count[i];
1477:     }

1479:     PetscCall(PetscFree(count));
1480:     PetscCall(PetscFree(indices));
1481:     PetscCall(ISDestroy(&isnumb));
1482:     PetscCall(ISDestroy(&ispart));
1483:   }
1484:   PetscFunctionReturn(PETSC_SUCCESS);
1485: }

1487: /*@C
1488:   PCASMDestroySubdomains - Destroys the index sets created with
1489:   `PCASMCreateSubdomains()`. Should be called after setting subdomains with `PCASMSetLocalSubdomains()`.

1491:   Collective

1493:   Input Parameters:
1494: + n        - the number of index sets
1495: . is       - the array of index sets
1496: - is_local - the array of local index sets, can be `NULL`

1498:   Level: advanced

1500: .seealso: [](ch_ksp), `PCASM`, `PCASMCreateSubdomains()`, `PCASMSetLocalSubdomains()`
1501: @*/
1502: PetscErrorCode PCASMDestroySubdomains(PetscInt n, IS is[], IS is_local[])
1503: {
1504:   PetscInt i;

1506:   PetscFunctionBegin;
1507:   if (n <= 0) PetscFunctionReturn(PETSC_SUCCESS);
1508:   if (is) {
1509:     PetscAssertPointer(is, 2);
1510:     for (i = 0; i < n; i++) PetscCall(ISDestroy(&is[i]));
1511:     PetscCall(PetscFree(is));
1512:   }
1513:   if (is_local) {
1514:     PetscAssertPointer(is_local, 3);
1515:     for (i = 0; i < n; i++) PetscCall(ISDestroy(&is_local[i]));
1516:     PetscCall(PetscFree(is_local));
1517:   }
1518:   PetscFunctionReturn(PETSC_SUCCESS);
1519: }

1521: /*@C
1522:   PCASMCreateSubdomains2D - Creates the index sets for the overlapping Schwarz
1523:   preconditioner, `PCASM`, for a two-dimensional problem on a regular grid.

1525:   Not Collective

1527:   Input Parameters:
1528: + m       - the number of mesh points in the x direction
1529: . n       - the number of mesh points in the y direction
1530: . M       - the number of subdomains in the x direction
1531: . N       - the number of subdomains in the y direction
1532: . dof     - degrees of freedom per node
1533: - overlap - overlap in mesh lines

1535:   Output Parameters:
1536: + Nsub     - the number of subdomains created
1537: . is       - array of index sets defining overlapping (if overlap > 0) subdomains
1538: - is_local - array of index sets defining non-overlapping subdomains

1540:   Level: advanced

1542:   Note:
1543:   Presently `PCAMSCreateSubdomains2d()` is valid only for sequential
1544:   preconditioners.  More general related routines are
1545:   `PCASMSetTotalSubdomains()` and `PCASMSetLocalSubdomains()`.

1547:   Fortran Notes:
1548:   `is` must be declared as an array of length long enough to hold `Nsub` entries

1550: .seealso: [](ch_ksp), `PCASM`, `PCASMSetTotalSubdomains()`, `PCASMSetLocalSubdomains()`, `PCASMGetSubKSP()`,
1551:           `PCASMSetOverlap()`
1552: @*/
1553: PetscErrorCode PCASMCreateSubdomains2D(PetscInt m, PetscInt n, PetscInt M, PetscInt N, PetscInt dof, PetscInt overlap, PetscInt *Nsub, IS **is, IS **is_local)
1554: {
1555:   PetscInt i, j, height, width, ystart, xstart, yleft, yright, xleft, xright, loc_outer;
1556:   PetscInt nidx, *idx, loc, ii, jj, count;

1558:   PetscFunctionBegin;
1559:   PetscCheck(dof == 1, PETSC_COMM_SELF, PETSC_ERR_SUP, "dof must be 1");

1561:   *Nsub = N * M;
1562:   PetscCall(PetscMalloc1(*Nsub, is));
1563:   PetscCall(PetscMalloc1(*Nsub, is_local));
1564:   ystart    = 0;
1565:   loc_outer = 0;
1566:   for (i = 0; i < N; i++) {
1567:     height = n / N + ((n % N) > i); /* height of subdomain */
1568:     PetscCheck(height >= 2, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Too many N subdomains for mesh dimension n");
1569:     yleft = ystart - overlap;
1570:     if (yleft < 0) yleft = 0;
1571:     yright = ystart + height + overlap;
1572:     if (yright > n) yright = n;
1573:     xstart = 0;
1574:     for (j = 0; j < M; j++) {
1575:       width = m / M + ((m % M) > j); /* width of subdomain */
1576:       PetscCheck(width >= 2, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Too many M subdomains for mesh dimension m");
1577:       xleft = xstart - overlap;
1578:       if (xleft < 0) xleft = 0;
1579:       xright = xstart + width + overlap;
1580:       if (xright > m) xright = m;
1581:       nidx = (xright - xleft) * (yright - yleft);
1582:       PetscCall(PetscMalloc1(nidx, &idx));
1583:       loc = 0;
1584:       for (ii = yleft; ii < yright; ii++) {
1585:         count = m * ii + xleft;
1586:         for (jj = xleft; jj < xright; jj++) idx[loc++] = count++;
1587:       }
1588:       PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nidx, idx, PETSC_COPY_VALUES, (*is) + loc_outer));
1589:       if (overlap == 0) {
1590:         PetscCall(PetscObjectReference((PetscObject)(*is)[loc_outer]));

1592:         (*is_local)[loc_outer] = (*is)[loc_outer];
1593:       } else {
1594:         for (loc = 0, ii = ystart; ii < ystart + height; ii++) {
1595:           for (jj = xstart; jj < xstart + width; jj++) idx[loc++] = m * ii + jj;
1596:         }
1597:         PetscCall(ISCreateGeneral(PETSC_COMM_SELF, loc, idx, PETSC_COPY_VALUES, *is_local + loc_outer));
1598:       }
1599:       PetscCall(PetscFree(idx));
1600:       xstart += width;
1601:       loc_outer++;
1602:     }
1603:     ystart += height;
1604:   }
1605:   for (i = 0; i < *Nsub; i++) PetscCall(ISSort((*is)[i]));
1606:   PetscFunctionReturn(PETSC_SUCCESS);
1607: }

1609: /*@C
1610:   PCASMGetLocalSubdomains - Gets the local subdomains (for this processor
1611:   only) for the additive Schwarz preconditioner, `PCASM`.

1613:   Not Collective

1615:   Input Parameter:
1616: . pc - the preconditioner context

1618:   Output Parameters:
1619: + n        - if requested, the number of subdomains for this processor (default value = 1)
1620: . is       - if requested, the index sets that define the subdomains for this processor
1621: - is_local - if requested, the index sets that define the local part of the subdomains for this processor (can be `NULL`)

1623:   Level: advanced

1625:   Note:
1626:   The `IS` numbering is in the parallel, global numbering of the vector.

1628:   Fortran Note:
1629:   Pass in for `is` and `is_local` arrays long enough to hold all the subdomains

1631: .seealso: [](ch_ksp), `PCASM`, `PCASMSetTotalSubdomains()`, `PCASMSetOverlap()`, `PCASMGetSubKSP()`,
1632:           `PCASMCreateSubdomains2D()`, `PCASMSetLocalSubdomains()`, `PCASMGetLocalSubmatrices()`
1633: @*/
1634: PetscErrorCode PCASMGetLocalSubdomains(PC pc, PetscInt *n, IS *is[], IS *is_local[])
1635: {
1636:   PC_ASM   *osm = (PC_ASM *)pc->data;
1637:   PetscBool match;

1639:   PetscFunctionBegin;
1641:   if (n) PetscAssertPointer(n, 2);
1642:   if (is) PetscAssertPointer(is, 3);
1643:   if (is_local) PetscAssertPointer(is_local, 4);
1644:   PetscCall(PetscObjectTypeCompare((PetscObject)pc, PCASM, &match));
1645:   PetscCheck(match, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONG, "PC is not a PCASM");
1646:   if (n) *n = osm->n_local_true;
1647:   if (is) *is = osm->is;
1648:   if (is_local) *is_local = osm->is_local;
1649:   PetscFunctionReturn(PETSC_SUCCESS);
1650: }

1652: /*@C
1653:   PCASMGetLocalSubmatrices - Gets the local submatrices (for this processor
1654:   only) for the additive Schwarz preconditioner, `PCASM`.

1656:   Not Collective

1658:   Input Parameter:
1659: . pc - the preconditioner context

1661:   Output Parameters:
1662: + n   - if requested, the number of matrices for this processor (default value = 1)
1663: - mat - if requested, the matrices

1665:   Level: advanced

1667:   Notes:
1668:   Call after `PCSetUp()` (or `KSPSetUp()`) but before `PCApply()` and before `PCSetUpOnBlocks()`)

1670:   Usually one would use `PCSetModifySubMatrices()` to change the submatrices in building the preconditioner.

1672:   Fortran Note:
1673:   Pass in for `mat` an array long enough to hold all the matrices

1675: .seealso: [](ch_ksp), `PCASM`, `PCASMSetTotalSubdomains()`, `PCASMSetOverlap()`, `PCASMGetSubKSP()`,
1676:           `PCASMCreateSubdomains2D()`, `PCASMSetLocalSubdomains()`, `PCASMGetLocalSubdomains()`, `PCSetModifySubMatrices()`
1677: @*/
1678: PetscErrorCode PCASMGetLocalSubmatrices(PC pc, PetscInt *n, Mat *mat[])
1679: {
1680:   PC_ASM   *osm;
1681:   PetscBool match;

1683:   PetscFunctionBegin;
1685:   if (n) PetscAssertPointer(n, 2);
1686:   if (mat) PetscAssertPointer(mat, 3);
1687:   PetscCheck(pc->setupcalled, PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONGSTATE, "Must call after KSPSetUp() or PCSetUp().");
1688:   PetscCall(PetscObjectTypeCompare((PetscObject)pc, PCASM, &match));
1689:   if (!match) {
1690:     if (n) *n = 0;
1691:     if (mat) *mat = NULL;
1692:   } else {
1693:     osm = (PC_ASM *)pc->data;
1694:     if (n) *n = osm->n_local_true;
1695:     if (mat) *mat = osm->pmat;
1696:   }
1697:   PetscFunctionReturn(PETSC_SUCCESS);
1698: }

1700: /*@
1701:   PCASMSetDMSubdomains - Indicates whether to use `DMCreateDomainDecomposition()` to define the subdomains, whenever possible.

1703:   Logically Collective

1705:   Input Parameters:
1706: + pc  - the preconditioner
1707: - flg - boolean indicating whether to use subdomains defined by the `DM`

1709:   Options Database Key:
1710: . -pc_asm_dm_subdomains <bool> - use subdomains defined by the `DM` with `DMCreateDomainDecomposition()`

1712:   Level: intermediate

1714:   Note:
1715:   `PCASMSetTotalSubdomains()` and `PCASMSetOverlap()` take precedence over `PCASMSetDMSubdomains()`,
1716:   so setting either of the first two effectively turns the latter off.

1718:   Developer Note:
1719:   This should be `PCASMSetUseDMSubdomains()`, similarly for the options database key

1721: .seealso: [](ch_ksp), `PCASM`, `PCASMGetDMSubdomains()`, `PCASMSetTotalSubdomains()`, `PCASMSetOverlap()`
1722:           `PCASMCreateSubdomains2D()`, `PCASMSetLocalSubdomains()`, `PCASMGetLocalSubdomains()`
1723: @*/
1724: PetscErrorCode PCASMSetDMSubdomains(PC pc, PetscBool flg)
1725: {
1726:   PC_ASM   *osm = (PC_ASM *)pc->data;
1727:   PetscBool match;

1729:   PetscFunctionBegin;
1732:   PetscCheck(!pc->setupcalled, ((PetscObject)pc)->comm, PETSC_ERR_ARG_WRONGSTATE, "Not for a setup PC.");
1733:   PetscCall(PetscObjectTypeCompare((PetscObject)pc, PCASM, &match));
1734:   if (match) osm->dm_subdomains = flg;
1735:   PetscFunctionReturn(PETSC_SUCCESS);
1736: }

1738: /*@
1739:   PCASMGetDMSubdomains - Returns flag indicating whether to use `DMCreateDomainDecomposition()` to define the subdomains, whenever possible.

1741:   Not Collective

1743:   Input Parameter:
1744: . pc - the preconditioner

1746:   Output Parameter:
1747: . flg - boolean indicating whether to use subdomains defined by the `DM`

1749:   Level: intermediate

1751:   Developer Note:
1752:   This should be `PCASMSetUseDMSubdomains()`

1754: .seealso: [](ch_ksp), `PCASM`, `PCASMSetDMSubdomains()`, `PCASMSetTotalSubdomains()`, `PCASMSetOverlap()`
1755:           `PCASMCreateSubdomains2D()`, `PCASMSetLocalSubdomains()`, `PCASMGetLocalSubdomains()`
1756: @*/
1757: PetscErrorCode PCASMGetDMSubdomains(PC pc, PetscBool *flg)
1758: {
1759:   PC_ASM   *osm = (PC_ASM *)pc->data;
1760:   PetscBool match;

1762:   PetscFunctionBegin;
1764:   PetscAssertPointer(flg, 2);
1765:   PetscCall(PetscObjectTypeCompare((PetscObject)pc, PCASM, &match));
1766:   if (match) *flg = osm->dm_subdomains;
1767:   else *flg = PETSC_FALSE;
1768:   PetscFunctionReturn(PETSC_SUCCESS);
1769: }

1771: /*@
1772:   PCASMGetSubMatType - Gets the matrix type used for `PCASM` subsolves, as a string.

1774:   Not Collective

1776:   Input Parameter:
1777: . pc - the `PC`

1779:   Output Parameter:
1780: . sub_mat_type - name of matrix type

1782:   Level: advanced

1784: .seealso: [](ch_ksp), `PCASM`, `PCASMSetSubMatType()`, `PCSetType()`, `VecSetType()`, `MatType`, `Mat`
1785: @*/
1786: PetscErrorCode PCASMGetSubMatType(PC pc, MatType *sub_mat_type)
1787: {
1788:   PetscFunctionBegin;
1790:   PetscTryMethod(pc, "PCASMGetSubMatType_C", (PC, MatType *), (pc, sub_mat_type));
1791:   PetscFunctionReturn(PETSC_SUCCESS);
1792: }

1794: /*@
1795:   PCASMSetSubMatType - Set the type of matrix used for `PCASM` subsolves

1797:   Collective

1799:   Input Parameters:
1800: + pc           - the `PC` object
1801: - sub_mat_type - the `MatType`

1803:   Options Database Key:
1804: . -pc_asm_sub_mat_type  <sub_mat_type> - Sets the matrix type used for subsolves, for example, seqaijviennacl.
1805:    If you specify a base name like aijviennacl, the corresponding sequential type is assumed.

1807:   Note:
1808:   See `MatType` for available types

1810:   Level: advanced

1812: .seealso: [](ch_ksp), `PCASM`, `PCASMGetSubMatType()`, `PCSetType()`, `VecSetType()`, `MatType`, `Mat`
1813: @*/
1814: PetscErrorCode PCASMSetSubMatType(PC pc, MatType sub_mat_type)
1815: {
1816:   PetscFunctionBegin;
1818:   PetscTryMethod(pc, "PCASMSetSubMatType_C", (PC, MatType), (pc, sub_mat_type));
1819:   PetscFunctionReturn(PETSC_SUCCESS);
1820: }