/* This assumes that the DM has been cloned prior to the call */ PetscErrorCode DMCreateSubDM_Section_Private(DM dm, PetscInt numFields, PetscInt fields[], IS *is, DM *subdm) { PetscSection section, sectionGlobal; PetscInt *subIndices; PetscInt subSize = 0, subOff = 0, nF, f, pStart, pEnd, p; PetscErrorCode ierr; PetscFunctionBegin; if (!numFields) PetscFunctionReturn(0); ierr = DMGetDefaultSection(dm, §ion);CHKERRQ(ierr); ierr = DMGetDefaultGlobalSection(dm, §ionGlobal);CHKERRQ(ierr); if (!section) SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Must set default section for DM before splitting fields"); if (!sectionGlobal) SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Must set default global section for DM before splitting fields"); ierr = PetscSectionGetNumFields(section, &nF);CHKERRQ(ierr); if (numFields > nF) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Number of requested fields %d greater than number of DM fields %d", numFields, nF); if (is) { ierr = PetscSectionGetChart(sectionGlobal, &pStart, &pEnd);CHKERRQ(ierr); for (p = pStart; p < pEnd; ++p) { PetscInt gdof; ierr = PetscSectionGetDof(sectionGlobal, p, &gdof);CHKERRQ(ierr); if (gdof > 0) { for (f = 0; f < numFields; ++f) { PetscInt fdof, fcdof; ierr = PetscSectionGetFieldDof(section, p, fields[f], &fdof);CHKERRQ(ierr); ierr = PetscSectionGetFieldConstraintDof(section, p, fields[f], &fcdof);CHKERRQ(ierr); subSize += fdof-fcdof; } } } ierr = PetscMalloc1(subSize, &subIndices);CHKERRQ(ierr); for (p = pStart; p < pEnd; ++p) { PetscInt gdof, goff; ierr = PetscSectionGetDof(sectionGlobal, p, &gdof);CHKERRQ(ierr); if (gdof > 0) { ierr = PetscSectionGetOffset(sectionGlobal, p, &goff);CHKERRQ(ierr); for (f = 0; f < numFields; ++f) { PetscInt fdof, fcdof, fc, f2, poff = 0; /* Can get rid of this loop by storing field information in the global section */ for (f2 = 0; f2 < fields[f]; ++f2) { ierr = PetscSectionGetFieldDof(section, p, f2, &fdof);CHKERRQ(ierr); ierr = PetscSectionGetFieldConstraintDof(section, p, f2, &fcdof);CHKERRQ(ierr); poff += fdof-fcdof; } ierr = PetscSectionGetFieldDof(section, p, fields[f], &fdof);CHKERRQ(ierr); ierr = PetscSectionGetFieldConstraintDof(section, p, fields[f], &fcdof);CHKERRQ(ierr); for (fc = 0; fc < fdof-fcdof; ++fc, ++subOff) { subIndices[subOff] = goff+poff+fc; } } } } ierr = ISCreateGeneral(PetscObjectComm((PetscObject)dm), subSize, subIndices, PETSC_OWN_POINTER, is);CHKERRQ(ierr); } if (subdm) { PetscSection subsection; PetscBool haveNull = PETSC_FALSE; PetscInt f, nf = 0; ierr = PetscSectionCreateSubsection(section, numFields, fields, &subsection);CHKERRQ(ierr); ierr = DMSetDefaultSection(*subdm, subsection);CHKERRQ(ierr); ierr = PetscSectionDestroy(&subsection);CHKERRQ(ierr); for (f = 0; f < numFields; ++f) { (*subdm)->nullspaceConstructors[f] = dm->nullspaceConstructors[fields[f]]; if ((*subdm)->nullspaceConstructors[f]) { haveNull = PETSC_TRUE; nf = f; } } if (haveNull && is) { MatNullSpace nullSpace; ierr = (*(*subdm)->nullspaceConstructors[nf])(*subdm, nf, &nullSpace);CHKERRQ(ierr); ierr = PetscObjectCompose((PetscObject) *is, "nullspace", (PetscObject) nullSpace);CHKERRQ(ierr); ierr = MatNullSpaceDestroy(&nullSpace);CHKERRQ(ierr); } if (dm->prob) { PetscInt Nf; ierr = PetscDSGetNumFields(dm->prob, &Nf);CHKERRQ(ierr); if (nF != Nf) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "The number of DM fields %d does not match the number of Section fields %d", Nf, nF); ierr = DMSetNumFields(*subdm, numFields);CHKERRQ(ierr); for (f = 0; f < numFields; ++f) { PetscObject disc; ierr = DMGetField(dm, fields[f], &disc);CHKERRQ(ierr); ierr = DMSetField(*subdm, f, disc);CHKERRQ(ierr); } if (numFields == 1 && is) { PetscObject disc, space, pmat; ierr = DMGetField(*subdm, 0, &disc);CHKERRQ(ierr); ierr = PetscObjectQuery(disc, "nullspace", &space);CHKERRQ(ierr); if (space) {ierr = PetscObjectCompose((PetscObject) *is, "nullspace", space);CHKERRQ(ierr);} ierr = PetscObjectQuery(disc, "nearnullspace", &space);CHKERRQ(ierr); if (space) {ierr = PetscObjectCompose((PetscObject) *is, "nearnullspace", space);CHKERRQ(ierr);} ierr = PetscObjectQuery(disc, "pmat", &pmat);CHKERRQ(ierr); if (pmat) {ierr = PetscObjectCompose((PetscObject) *is, "pmat", pmat);CHKERRQ(ierr);} } } } #if 0 /* We need a way to filter the original SF for given fields: - Keeping the original section around it too much I think - We could keep the distributed section, and subset it */ if (dm->sfNatural) { PetscSF sfNatural; ierr = PetscSectionCreateSubsection(dm->originalSection, numFields, fields, &(*subdm)->originalSection);CHKERRQ(ierr); ierr = DMPlexCreateGlobalToNaturalPetscSF(*subdm, &sfNatural);CHKERRQ(ierr); ierr = DMPlexSetGlobalToNaturalPetscSF(*subdm, sfNatural);CHKERRQ(ierr); } #endif PetscFunctionReturn(0); }
//! Help PETSc identify the coarser DM dmc given the fine DM dmf PetscErrorCode libmesh_petsc_DMCoarsen(DM dmf, MPI_Comm /*comm*/, DM * dmc) { libmesh_assert(dmc); libmesh_assert(dmf); PetscErrorCode ierr; // Extract our context from the incoming dmf void * ctx_f = nullptr; ierr = DMShellGetContext(dmf, &ctx_f);LIBMESH_CHKERR(ierr); libmesh_assert(ctx_f); PetscDMContext * p_ctx = static_cast<PetscDMContext*>(ctx_f); // First, ensure that there exists a coarse DM that we want to // set. There ought to be as we created it while walking the // hierarchy. libmesh_assert(p_ctx->coarser_dm); libmesh_assert(*(p_ctx->coarser_dm)); // In situations using fieldsplit we need to (potentially) // provide a coarser DM which only has the relevant subfields in // it. Since we create global DMs for each mesh level, we need // to extract the section from the DM, and check the number of // fields. When less than all the fields are used, we need to // create the proper subsections. // Get the number of fields and their names from the incomming // fine DM and the global reference DM PetscInt nfieldsf, nfieldsg; char ** fieldnamesf; char ** fieldnamesg; libmesh_assert(p_ctx->global_dm); DM * globaldm = p_ctx->global_dm; ierr = DMCreateFieldIS(dmf, &nfieldsf, &fieldnamesf, nullptr); LIBMESH_CHKERR(ierr); ierr = DMCreateFieldIS(*globaldm, &nfieldsg, &fieldnamesg, nullptr); LIBMESH_CHKERR(ierr); // If the probed number of fields is less than the number of // global fields, this amounts to PETSc 'indicating' to us we // are doing FS. So, we must create subsections for the coarser // DMs. if ( nfieldsf < nfieldsg ) { PetscSection section; PetscSection subsection; std::vector<PetscInt> subfields(nfieldsf); // extracted fields // First, get the section from the coarse DM #if PETSC_VERSION_LESS_THAN(3,10,0) ierr = DMGetDefaultSection(*(p_ctx->coarser_dm), §ion); #else ierr = DMGetSection(*(p_ctx->coarser_dm), §ion); #endif LIBMESH_CHKERR(ierr); // Now, match fine grid DM field names to their global DM // counterparts. Since PETSc can internally reassign field // numbering under a fieldsplit, we must extract // subsections via the field names. This is admittedly // gross, but c'est la vie. for (int i = 0; i < nfieldsf ; i++) { for (int j = 0; j < nfieldsg ;j++) if ( strcmp( fieldnamesg[j], fieldnamesf[i] ) == 0 ) subfields[i] = j; } // Next, for the found fields we now make a subsection and set it for the coarser DM ierr = PetscSectionCreateSubsection(section, nfieldsf, subfields.data(), &subsection); LIBMESH_CHKERR(ierr); #if PETSC_VERSION_LESS_THAN(3,10,0) ierr = DMSetDefaultSection(*(p_ctx->coarser_dm) , subsection); #else ierr = DMSetSection(*(p_ctx->coarser_dm) , subsection); #endif LIBMESH_CHKERR(ierr); ierr = PetscSectionDestroy(&subsection); LIBMESH_CHKERR(ierr); } // Finally, set the coarser DM *(dmc) = *(p_ctx->coarser_dm); return 0; }
/* This assumes that the DM has been cloned prior to the call */ PetscErrorCode DMCreateSubDM_Section_Private(DM dm, PetscInt numFields, PetscInt fields[], IS *is, DM *subdm) { PetscSection section, sectionGlobal; PetscInt *subIndices; PetscInt subSize = 0, subOff = 0, nF, f, pStart, pEnd, p; PetscErrorCode ierr; PetscFunctionBegin; if (!numFields) PetscFunctionReturn(0); ierr = DMGetDefaultSection(dm, §ion);CHKERRQ(ierr); ierr = DMGetDefaultGlobalSection(dm, §ionGlobal);CHKERRQ(ierr); if (!section) SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Must set default section for DM before splitting fields"); if (!sectionGlobal) SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Must set default global section for DM before splitting fields"); ierr = PetscSectionGetNumFields(section, &nF);CHKERRQ(ierr); if (numFields > nF) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Number of requested fields %d greater than number of DM fields %d", numFields, nF); if (is) { ierr = PetscSectionGetChart(sectionGlobal, &pStart, &pEnd);CHKERRQ(ierr); for (p = pStart; p < pEnd; ++p) { PetscInt gdof; ierr = PetscSectionGetDof(sectionGlobal, p, &gdof);CHKERRQ(ierr); if (gdof > 0) { for (f = 0; f < numFields; ++f) { PetscInt fdof, fcdof; ierr = PetscSectionGetFieldDof(section, p, fields[f], &fdof);CHKERRQ(ierr); ierr = PetscSectionGetFieldConstraintDof(section, p, fields[f], &fcdof);CHKERRQ(ierr); subSize += fdof-fcdof; } } } ierr = PetscMalloc1(subSize, &subIndices);CHKERRQ(ierr); for (p = pStart; p < pEnd; ++p) { PetscInt gdof, goff; ierr = PetscSectionGetDof(sectionGlobal, p, &gdof);CHKERRQ(ierr); if (gdof > 0) { ierr = PetscSectionGetOffset(sectionGlobal, p, &goff);CHKERRQ(ierr); for (f = 0; f < numFields; ++f) { PetscInt fdof, fcdof, fc, f2, poff = 0; /* Can get rid of this loop by storing field information in the global section */ for (f2 = 0; f2 < fields[f]; ++f2) { ierr = PetscSectionGetFieldDof(section, p, f2, &fdof);CHKERRQ(ierr); ierr = PetscSectionGetFieldConstraintDof(section, p, f2, &fcdof);CHKERRQ(ierr); poff += fdof-fcdof; } ierr = PetscSectionGetFieldDof(section, p, fields[f], &fdof);CHKERRQ(ierr); ierr = PetscSectionGetFieldConstraintDof(section, p, fields[f], &fcdof);CHKERRQ(ierr); for (fc = 0; fc < fdof-fcdof; ++fc, ++subOff) { subIndices[subOff] = goff+poff+fc; } } } } ierr = ISCreateGeneral(PetscObjectComm((PetscObject)dm), subSize, subIndices, PETSC_OWN_POINTER, is);CHKERRQ(ierr); } if (subdm) { PetscSection subsection; PetscBool haveNull = PETSC_FALSE; PetscInt f, nf = 0; ierr = PetscSectionCreateSubsection(section, numFields, fields, &subsection);CHKERRQ(ierr); ierr = DMSetDefaultSection(*subdm, subsection);CHKERRQ(ierr); ierr = PetscSectionDestroy(&subsection);CHKERRQ(ierr); for (f = 0; f < numFields; ++f) { (*subdm)->nullspaceConstructors[f] = dm->nullspaceConstructors[fields[f]]; if ((*subdm)->nullspaceConstructors[f]) { haveNull = PETSC_TRUE; nf = f; } } if (haveNull) { MatNullSpace nullSpace; ierr = (*(*subdm)->nullspaceConstructors[nf])(*subdm, nf, &nullSpace);CHKERRQ(ierr); ierr = PetscObjectCompose((PetscObject) *is, "nullspace", (PetscObject) nullSpace);CHKERRQ(ierr); ierr = MatNullSpaceDestroy(&nullSpace);CHKERRQ(ierr); } if (dm->fields) { if (nF != dm->numFields) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "The number of DM fields %d does not match the number of Section fields %d", dm->numFields, nF); ierr = DMSetNumFields(*subdm, numFields);CHKERRQ(ierr); for (f = 0; f < numFields; ++f) { ierr = PetscObjectListDuplicate(dm->fields[fields[f]]->olist, &(*subdm)->fields[f]->olist);CHKERRQ(ierr); } if (numFields == 1) { MatNullSpace space; Mat pmat; ierr = PetscObjectQuery((*subdm)->fields[0], "nullspace", (PetscObject*) &space);CHKERRQ(ierr); if (space) {ierr = PetscObjectCompose((PetscObject) *is, "nullspace", (PetscObject) space);CHKERRQ(ierr);} ierr = PetscObjectQuery((*subdm)->fields[0], "nearnullspace", (PetscObject*) &space);CHKERRQ(ierr); if (space) {ierr = PetscObjectCompose((PetscObject) *is, "nearnullspace", (PetscObject) space);CHKERRQ(ierr);} ierr = PetscObjectQuery((*subdm)->fields[0], "pmat", (PetscObject*) &pmat);CHKERRQ(ierr); if (pmat) {ierr = PetscObjectCompose((PetscObject) *is, "pmat", (PetscObject) pmat);CHKERRQ(ierr);} } } } PetscFunctionReturn(0); }