Date: 2022-08-02T03:14:23+00:00

Actual source code: dmi.c

      1: #include <petsc/private/dmimpl.h>
      2: #include <petscds.h>

      4: // Greatest common divisor of two nonnegative integers
      5: PetscInt PetscGCD(PetscInt a, PetscInt b) {
      6:   while (b != 0) {
      7:     PetscInt tmp = b;
      8:     b = a % b;
      9:     a = tmp;
     10:   }
     11:   return a;
     12: }

     14: PetscErrorCode DMCreateGlobalVector_Section_Private(DM dm,Vec *vec)
     15: {
     16:   PetscSection   gSection;
     17:   PetscInt       localSize, bs, blockSize = -1, pStart, pEnd, p;
     18:   PetscInt       in[2],out[2];

     20:   DMGetGlobalSection(dm, &gSection);
     21:   PetscSectionGetChart(gSection, &pStart, &pEnd);
     22:   for (p = pStart; p < pEnd; ++p) {
     23:     PetscInt dof, cdof;

     25:     PetscSectionGetDof(gSection, p, &dof);
     26:     PetscSectionGetConstraintDof(gSection, p, &cdof);

     28:     if (dof - cdof > 0) {
     29:       if (blockSize < 0) {
     30:         /* set blockSize */
     31:         blockSize = dof-cdof;
     32:       } else {
     33:         blockSize = PetscGCD(dof - cdof, blockSize);
     34:       }
     35:     }
     36:   }

     38:   in[0] = blockSize < 0 ? PETSC_MIN_INT : -blockSize;
     39:   in[1] = blockSize;
     40:   MPIU_Allreduce(in,out,2,MPIU_INT,MPI_MAX,PetscObjectComm((PetscObject)dm));
     41:   /* -out[0] = min(blockSize), out[1] = max(blockSize) */
     42:   if (-out[0] == out[1]) {
     43:     bs = out[1];
     44:   } else bs = 1;

     46:   if (bs < 0) { /* Everyone was empty */
     47:     blockSize = 1;
     48:     bs        = 1;
     49:   }

     51:   PetscSectionGetConstrainedStorageSize(gSection, &localSize);
     53:   VecCreate(PetscObjectComm((PetscObject)dm), vec);
     54:   VecSetSizes(*vec, localSize, PETSC_DETERMINE);
     55:   VecSetBlockSize(*vec, bs);
     56:   VecSetType(*vec,dm->vectype);
     57:   VecSetDM(*vec, dm);
     58:   /* VecSetLocalToGlobalMapping(*vec, dm->ltogmap); */
     59:   return 0;
     60: }

     62: PetscErrorCode DMCreateLocalVector_Section_Private(DM dm,Vec *vec)
     63: {
     64:   PetscSection   section;
     65:   PetscInt       localSize, blockSize = -1, pStart, pEnd, p;

     67:   DMGetLocalSection(dm, &section);
     68:   PetscSectionGetChart(section, &pStart, &pEnd);
     69:   for (p = pStart; p < pEnd; ++p) {
     70:     PetscInt dof;

     72:     PetscSectionGetDof(section, p, &dof);
     73:     if ((blockSize < 0) && (dof > 0)) blockSize = dof;
     74:     if (dof > 0) blockSize = PetscGCD(dof, blockSize);
     75:   }
     76:   PetscSectionGetStorageSize(section, &localSize);
     77:   VecCreate(PETSC_COMM_SELF, vec);
     78:   VecSetSizes(*vec, localSize, localSize);
     79:   VecSetBlockSize(*vec, blockSize);
     80:   VecSetType(*vec,dm->vectype);
     81:   VecSetDM(*vec, dm);
     82:   return 0;
     83: }

     85: /*@C
     86:   DMCreateSectionSubDM - Returns an IS and subDM+subSection encapsulating a subproblem defined by the fields in a PetscSection in the DM.

     88:   Not collective

     90:   Input Parameters:
     91: + dm        - The DM object
     92: . numFields - The number of fields in this subproblem
     93: - fields    - The field numbers of the selected fields

     95:   Output Parameters:
     96: + is - The global indices for the subproblem
     97: - subdm - The DM for the subproblem, which must already have be cloned from dm

     99:   Note: This handles all information in the DM class and the PetscSection. This is used as the basis for creating subDMs in specialized classes,
    100:   such as Plex and Forest.

    102:   Level: intermediate

    104: .seealso DMCreateSubDM(), DMGetLocalSection(), DMPlexSetMigrationSF(), DMView()
    105: @*/
    106: PetscErrorCode DMCreateSectionSubDM(DM dm, PetscInt numFields, const PetscInt fields[], IS *is, DM *subdm)
    107: {
    108:   PetscSection   section, sectionGlobal;
    109:   PetscInt      *subIndices;
    110:   PetscInt       subSize = 0, subOff = 0, Nf, f, pStart, pEnd, p;

    112:   if (!numFields) return 0;
    113:   DMGetLocalSection(dm, &section);
    114:   DMGetGlobalSection(dm, &sectionGlobal);
    117:   PetscSectionGetNumFields(section, &Nf);
    119:   if (is) {
    120:     PetscInt bs, bsLocal[2], bsMinMax[2];

    122:     for (f = 0, bs = 0; f < numFields; ++f) {
    123:       PetscInt Nc;

    125:       PetscSectionGetFieldComponents(section, fields[f], &Nc);
    126:       bs  += Nc;
    127:     }
    128:     PetscSectionGetChart(sectionGlobal, &pStart, &pEnd);
    129:     for (p = pStart; p < pEnd; ++p) {
    130:       PetscInt gdof, pSubSize  = 0;

    132:       PetscSectionGetDof(sectionGlobal, p, &gdof);
    133:       if (gdof > 0) {
    134:         for (f = 0; f < numFields; ++f) {
    135:           PetscInt fdof, fcdof;

    137:           PetscSectionGetFieldDof(section, p, fields[f], &fdof);
    138:           PetscSectionGetFieldConstraintDof(section, p, fields[f], &fcdof);
    139:           pSubSize += fdof-fcdof;
    140:         }
    141:         subSize += pSubSize;
    142:         if (pSubSize && bs != pSubSize) {
    143:           /* Layout does not admit a pointwise block size */
    144:           bs = 1;
    145:         }
    146:       }
    147:     }
    148:     /* Must have same blocksize on all procs (some might have no points) */
    149:     bsLocal[0] = bs < 0 ? PETSC_MAX_INT : bs; bsLocal[1] = bs;
    150:     PetscGlobalMinMaxInt(PetscObjectComm((PetscObject) dm), bsLocal, bsMinMax);
    151:     if (bsMinMax[0] != bsMinMax[1]) {bs = 1;}
    152:     else                            {bs = bsMinMax[0];}
    153:     PetscMalloc1(subSize, &subIndices);
    154:     for (p = pStart; p < pEnd; ++p) {
    155:       PetscInt gdof, goff;

    157:       PetscSectionGetDof(sectionGlobal, p, &gdof);
    158:       if (gdof > 0) {
    159:         PetscSectionGetOffset(sectionGlobal, p, &goff);
    160:         for (f = 0; f < numFields; ++f) {
    161:           PetscInt fdof, fcdof, fc, f2, poff = 0;

    163:           /* Can get rid of this loop by storing field information in the global section */
    164:           for (f2 = 0; f2 < fields[f]; ++f2) {
    165:             PetscSectionGetFieldDof(section, p, f2, &fdof);
    166:             PetscSectionGetFieldConstraintDof(section, p, f2, &fcdof);
    167:             poff += fdof-fcdof;
    168:           }
    169:           PetscSectionGetFieldDof(section, p, fields[f], &fdof);
    170:           PetscSectionGetFieldConstraintDof(section, p, fields[f], &fcdof);
    171:           for (fc = 0; fc < fdof-fcdof; ++fc, ++subOff) {
    172:             subIndices[subOff] = goff+poff+fc;
    173:           }
    174:         }
    175:       }
    176:     }
    177:     ISCreateGeneral(PetscObjectComm((PetscObject)dm), subSize, subIndices, PETSC_OWN_POINTER, is);
    178:     if (bs > 1) {
    179:       /* We need to check that the block size does not come from non-contiguous fields */
    180:       PetscInt i, j, set = 1;
    181:       for (i = 0; i < subSize; i += bs) {
    182:         for (j = 0; j < bs; ++j) {
    183:           if (subIndices[i+j] != subIndices[i]+j) {set = 0; break;}
    184:         }
    185:       }
    186:       if (set) ISSetBlockSize(*is, bs);
    187:     }
    188:   }
    189:   if (subdm) {
    190:     PetscSection subsection;
    191:     PetscBool    haveNull = PETSC_FALSE;
    192:     PetscInt     f, nf = 0, of = 0;

    194:     PetscSectionCreateSubsection(section, numFields, fields, &subsection);
    195:     DMSetLocalSection(*subdm, subsection);
    196:     PetscSectionDestroy(&subsection);
    197:     for (f = 0; f < numFields; ++f) {
    198:       (*subdm)->nullspaceConstructors[f] = dm->nullspaceConstructors[fields[f]];
    199:       if ((*subdm)->nullspaceConstructors[f]) {
    200:         haveNull = PETSC_TRUE;
    201:         nf       = f;
    202:         of       = fields[f];
    203:       }
    204:     }
    205:     if (dm->probs) {
    206:       DMSetNumFields(*subdm, numFields);
    207:       for (f = 0; f < numFields; ++f) {
    208:         PetscObject disc;

    210:         DMGetField(dm, fields[f], NULL, &disc);
    211:         DMSetField(*subdm, f, NULL, disc);
    212:       }
    213:       DMCreateDS(*subdm);
    214:       if (numFields == 1 && is) {
    215:         PetscObject disc, space, pmat;

    217:         DMGetField(*subdm, 0, NULL, &disc);
    218:         PetscObjectQuery(disc, "nullspace", &space);
    219:         if (space) PetscObjectCompose((PetscObject) *is, "nullspace", space);
    220:         PetscObjectQuery(disc, "nearnullspace", &space);
    221:         if (space) PetscObjectCompose((PetscObject) *is, "nearnullspace", space);
    222:         PetscObjectQuery(disc, "pmat", &pmat);
    223:         if (pmat) PetscObjectCompose((PetscObject) *is, "pmat", pmat);
    224:       }
    225:       /* Check if DSes record their DM fields */
    226:       if (dm->probs[0].fields) {
    227:         PetscInt d, e;

    229:         for (d = 0, e = 0; d < dm->Nds && e < (*subdm)->Nds; ++d) {
    230:           const PetscInt  Nf = dm->probs[d].ds->Nf;
    231:           const PetscInt *fld;
    232:           PetscInt        f, g;

    234:           ISGetIndices(dm->probs[d].fields, &fld);
    235:           for (f = 0; f < Nf; ++f) {
    236:             for (g = 0; g < numFields; ++g) if (fld[f] == fields[g]) break;
    237:             if (g < numFields) break;
    238:           }
    239:           ISRestoreIndices(dm->probs[d].fields, &fld);
    240:           if (f == Nf) continue;
    241:           PetscDSCopyConstants(dm->probs[d].ds, (*subdm)->probs[e].ds);
    242:           PetscDSCopyBoundary(dm->probs[d].ds, numFields, fields, (*subdm)->probs[e].ds);
    243:           /* Translate DM fields to DS fields */
    244:           {
    245:             IS              infields, dsfields;
    246:             const PetscInt *fld, *ofld;
    247:             PetscInt       *fidx;
    248:             PetscInt        onf, nf, f, g;

    250:             ISCreateGeneral(PETSC_COMM_SELF, numFields, fields, PETSC_USE_POINTER, &infields);
    251:             ISIntersect(infields, dm->probs[d].fields, &dsfields);
    252:             ISDestroy(&infields);
    253:             ISGetLocalSize(dsfields, &nf);
    255:             ISGetIndices(dsfields, &fld);
    256:             ISGetLocalSize(dm->probs[d].fields, &onf);
    257:             ISGetIndices(dm->probs[d].fields, &ofld);
    258:             PetscMalloc1(nf, &fidx);
    259:             for (f = 0, g = 0; f < onf && g < nf; ++f) {
    260:               if (ofld[f] == fld[g]) fidx[g++] = f;
    261:             }
    262:             ISRestoreIndices(dm->probs[d].fields, &ofld);
    263:             ISRestoreIndices(dsfields, &fld);
    264:             ISDestroy(&dsfields);
    265:             PetscDSSelectDiscretizations(dm->probs[0].ds, nf, fidx, (*subdm)->probs[0].ds);
    266:             PetscDSSelectEquations(dm->probs[0].ds, nf, fidx, (*subdm)->probs[0].ds);
    267:             PetscFree(fidx);
    268:           }
    269:           ++e;
    270:         }
    271:       } else {
    272:         PetscDSCopyConstants(dm->probs[0].ds, (*subdm)->probs[0].ds);
    273:         PetscDSCopyBoundary(dm->probs[0].ds, PETSC_DETERMINE, NULL, (*subdm)->probs[0].ds);
    274:         PetscDSSelectDiscretizations(dm->probs[0].ds, numFields, fields, (*subdm)->probs[0].ds);
    275:         PetscDSSelectEquations(dm->probs[0].ds, numFields, fields, (*subdm)->probs[0].ds);
    276:       }
    277:     }
    278:     if (haveNull && is) {
    279:       MatNullSpace nullSpace;

    281:       (*(*subdm)->nullspaceConstructors[nf])(*subdm, of, nf, &nullSpace);
    282:       PetscObjectCompose((PetscObject) *is, "nullspace", (PetscObject) nullSpace);
    283:       MatNullSpaceDestroy(&nullSpace);
    284:     }
    285:     if (dm->coarseMesh) {
    286:       DMCreateSubDM(dm->coarseMesh, numFields, fields, NULL, &(*subdm)->coarseMesh);
    287:     }
    288:   }
    289:   return 0;
    290: }

    292: /*@C
    293:   DMCreateSectionSuperDM - Returns an arrays of ISes and DM+Section encapsulating a superproblem defined by the DM+Sections passed in.

    295:   Not collective

    297:   Input Parameters:
    298: + dms - The DM objects
    299: - len - The number of DMs

    301:   Output Parameters:
    302: + is - The global indices for the subproblem, or NULL
    303: - superdm - The DM for the superproblem, which must already have be cloned

    305:   Note: This handles all information in the DM class and the PetscSection. This is used as the basis for creating subDMs in specialized classes,
    306:   such as Plex and Forest.

    308:   Level: intermediate

    310: .seealso DMCreateSuperDM(), DMGetLocalSection(), DMPlexSetMigrationSF(), DMView()
    311: @*/
    312: PetscErrorCode DMCreateSectionSuperDM(DM dms[], PetscInt len, IS **is, DM *superdm)
    313: {
    314:   MPI_Comm       comm;
    315:   PetscSection   supersection, *sections, *sectionGlobals;
    316:   PetscInt      *Nfs, Nf = 0, f, supf, oldf = -1, nullf = -1, i;
    317:   PetscBool      haveNull = PETSC_FALSE;

    319:   PetscObjectGetComm((PetscObject)dms[0], &comm);
    320:   /* Pull out local and global sections */
    321:   PetscMalloc3(len, &Nfs, len, &sections, len, &sectionGlobals);
    322:   for (i = 0 ; i < len; ++i) {
    323:     DMGetLocalSection(dms[i], &sections[i]);
    324:     DMGetGlobalSection(dms[i], &sectionGlobals[i]);
    327:     PetscSectionGetNumFields(sections[i], &Nfs[i]);
    328:     Nf += Nfs[i];
    329:   }
    330:   /* Create the supersection */
    331:   PetscSectionCreateSupersection(sections, len, &supersection);
    332:   DMSetLocalSection(*superdm, supersection);
    333:   /* Create ISes */
    334:   if (is) {
    335:     PetscSection supersectionGlobal;
    336:     PetscInt     bs = -1, startf = 0;

    338:     PetscMalloc1(len, is);
    339:     DMGetGlobalSection(*superdm, &supersectionGlobal);
    340:     for (i = 0 ; i < len; startf += Nfs[i], ++i) {
    341:       PetscInt *subIndices;
    342:       PetscInt  subSize, subOff, pStart, pEnd, p, start, end, dummy;

    344:       PetscSectionGetChart(sectionGlobals[i], &pStart, &pEnd);
    345:       PetscSectionGetConstrainedStorageSize(sectionGlobals[i], &subSize);
    346:       PetscMalloc1(subSize, &subIndices);
    347:       for (p = pStart, subOff = 0; p < pEnd; ++p) {
    348:         PetscInt gdof, gcdof, gtdof, d;

    350:         PetscSectionGetDof(sectionGlobals[i], p, &gdof);
    351:         PetscSectionGetConstraintDof(sections[i], p, &gcdof);
    352:         gtdof = gdof - gcdof;
    353:         if (gdof > 0 && gtdof) {
    354:           if (bs < 0)           {bs = gtdof;}
    355:           else if (bs != gtdof) {bs = 1;}
    356:           DMGetGlobalFieldOffset_Private(*superdm, p, startf, &start, &dummy);
    357:           DMGetGlobalFieldOffset_Private(*superdm, p, startf+Nfs[i]-1, &dummy, &end);
    359:           for (d = start; d < end; ++d, ++subOff) subIndices[subOff] = d;
    360:         }
    361:       }
    362:       ISCreateGeneral(comm, subSize, subIndices, PETSC_OWN_POINTER, &(*is)[i]);
    363:       /* Must have same blocksize on all procs (some might have no points) */
    364:       {
    365:         PetscInt bs = -1, bsLocal[2], bsMinMax[2];

    367:         bsLocal[0] = bs < 0 ? PETSC_MAX_INT : bs; bsLocal[1] = bs;
    368:         PetscGlobalMinMaxInt(comm, bsLocal, bsMinMax);
    369:         if (bsMinMax[0] != bsMinMax[1]) {bs = 1;}
    370:         else                            {bs = bsMinMax[0];}
    371:         ISSetBlockSize((*is)[i], bs);
    372:       }
    373:     }
    374:   }
    375:   /* Preserve discretizations */
    376:   if (len && dms[0]->probs) {
    377:     DMSetNumFields(*superdm, Nf);
    378:     for (i = 0, supf = 0; i < len; ++i) {
    379:       for (f = 0; f < Nfs[i]; ++f, ++supf) {
    380:         PetscObject disc;

    382:         DMGetField(dms[i], f, NULL, &disc);
    383:         DMSetField(*superdm, supf, NULL, disc);
    384:       }
    385:     }
    386:     DMCreateDS(*superdm);
    387:   }
    388:   /* Preserve nullspaces */
    389:   for (i = 0, supf = 0; i < len; ++i) {
    390:     for (f = 0; f < Nfs[i]; ++f, ++supf) {
    391:       (*superdm)->nullspaceConstructors[supf] = dms[i]->nullspaceConstructors[f];
    392:       if ((*superdm)->nullspaceConstructors[supf]) {
    393:         haveNull = PETSC_TRUE;
    394:         nullf    = supf;
    395:         oldf     = f;
    396:       }
    397:     }
    398:   }
    399:   /* Attach nullspace to IS */
    400:   if (haveNull && is) {
    401:     MatNullSpace nullSpace;

    403:     (*(*superdm)->nullspaceConstructors[nullf])(*superdm, oldf, nullf, &nullSpace);
    404:     PetscObjectCompose((PetscObject) (*is)[nullf], "nullspace", (PetscObject) nullSpace);
    405:     MatNullSpaceDestroy(&nullSpace);
    406:   }
    407:   PetscSectionDestroy(&supersection);
    408:   PetscFree3(Nfs, sections, sectionGlobals);
    409:   return 0;
    410: }