Actual source code: bddcgraph.c

      1: #include <petsc/private/petscimpl.h>
      2: #include <petsc/private/pcbddcprivateimpl.h>
      3: #include <petsc/private/pcbddcstructsimpl.h>
      4: #include <petsc/private/hashmapi.h>
      5: #include <petsc/private/pcbddcgraphhashmap.h>
      6: #include <petscsf.h>

      8: PetscErrorCode PCBDDCDestroyGraphCandidatesIS(void **ctx)
      9: {
     10:   PCBDDCGraphCandidates cand = (PCBDDCGraphCandidates)*ctx;

     12:   PetscFunctionBegin;
     13:   for (PetscInt i = 0; i < cand->nfc; i++) PetscCall(ISDestroy(&cand->Faces[i]));
     14:   for (PetscInt i = 0; i < cand->nec; i++) PetscCall(ISDestroy(&cand->Edges[i]));
     15:   PetscCall(PetscFree(cand->Faces));
     16:   PetscCall(PetscFree(cand->Edges));
     17:   PetscCall(ISDestroy(&cand->Vertices));
     18:   PetscCall(PetscFree(cand));
     19:   PetscFunctionReturn(PETSC_SUCCESS);
     20: }

     22: PetscErrorCode PCBDDCGraphGetDirichletDofsB(PCBDDCGraph graph, IS *dirdofs)
     23: {
     24:   PetscFunctionBegin;
     25:   if (graph->dirdofsB) {
     26:     PetscCall(PetscObjectReference((PetscObject)graph->dirdofsB));
     27:   } else if (graph->has_dirichlet) {
     28:     PetscInt  i, size;
     29:     PetscInt *dirdofs_idxs;

     31:     size = 0;
     32:     for (i = 0; i < graph->nvtxs; i++) {
     33:       if (graph->nodes[i].count > 1 && graph->nodes[i].special_dof == PCBDDCGRAPH_DIRICHLET_MARK) size++;
     34:     }

     36:     PetscCall(PetscMalloc1(size, &dirdofs_idxs));
     37:     size = 0;
     38:     for (i = 0; i < graph->nvtxs; i++) {
     39:       if (graph->nodes[i].count > 1 && graph->nodes[i].special_dof == PCBDDCGRAPH_DIRICHLET_MARK) dirdofs_idxs[size++] = i;
     40:     }
     41:     PetscCall(ISCreateGeneral(PETSC_COMM_SELF, size, dirdofs_idxs, PETSC_OWN_POINTER, &graph->dirdofsB));
     42:     PetscCall(PetscObjectReference((PetscObject)graph->dirdofsB));
     43:   }
     44:   *dirdofs = graph->dirdofsB;
     45:   PetscFunctionReturn(PETSC_SUCCESS);
     46: }

     48: PetscErrorCode PCBDDCGraphGetDirichletDofs(PCBDDCGraph graph, IS *dirdofs)
     49: {
     50:   PetscFunctionBegin;
     51:   if (graph->dirdofs) {
     52:     PetscCall(PetscObjectReference((PetscObject)graph->dirdofs));
     53:   } else if (graph->has_dirichlet) {
     54:     PetscInt  i, size;
     55:     PetscInt *dirdofs_idxs;

     57:     size = 0;
     58:     for (i = 0; i < graph->nvtxs; i++) {
     59:       if (graph->nodes[i].special_dof == PCBDDCGRAPH_DIRICHLET_MARK) size++;
     60:     }

     62:     PetscCall(PetscMalloc1(size, &dirdofs_idxs));
     63:     size = 0;
     64:     for (i = 0; i < graph->nvtxs; i++) {
     65:       if (graph->nodes[i].special_dof == PCBDDCGRAPH_DIRICHLET_MARK) dirdofs_idxs[size++] = i;
     66:     }
     67:     PetscCall(ISCreateGeneral(PetscObjectComm((PetscObject)graph->l2gmap), size, dirdofs_idxs, PETSC_OWN_POINTER, &graph->dirdofs));
     68:     PetscCall(PetscObjectReference((PetscObject)graph->dirdofs));
     69:   }
     70:   *dirdofs = graph->dirdofs;
     71:   PetscFunctionReturn(PETSC_SUCCESS);
     72: }

     74: PetscErrorCode PCBDDCGraphASCIIView(PCBDDCGraph graph, PetscInt verbosity_level, PetscViewer viewer)
     75: {
     76:   PetscInt  i, j, tabs;
     77:   PetscInt *queue_in_global_numbering;

     79:   PetscFunctionBegin;
     80:   if (!viewer) PetscCall(PetscViewerASCIIGetStdout(graph->seq_graph ? PETSC_COMM_SELF : PetscObjectComm((PetscObject)graph->l2gmap), &viewer));
     81:   PetscCall(PetscViewerASCIIPushSynchronized(viewer));
     82:   PetscCall(PetscViewerASCIIGetTab(viewer, &tabs));
     83:   PetscCall(PetscViewerASCIIPrintf(viewer, "--------------------------------------------------\n"));
     84:   PetscCall(PetscViewerFlush(viewer));
     85:   PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "Local BDDC graph for subdomain %04d (seq %d)\n", PetscGlobalRank, graph->seq_graph));
     86:   PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "Number of vertices %" PetscInt_FMT "\n", graph->nvtxs));
     87:   PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "Number of local subdomains %" PetscInt_FMT "\n", graph->n_local_subs ? graph->n_local_subs : 1));
     88:   PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "Custom minimal size %" PetscInt_FMT "\n", graph->custom_minimal_size));
     89:   if (graph->maxcount != PETSC_INT_MAX) PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "Max count %" PetscInt_FMT "\n", graph->maxcount));
     90:   PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "Topological two dim? %s (set %s)\n", PetscBools[graph->twodim], PetscBools[graph->twodimset]));
     91:   if (verbosity_level > 2) {
     92:     for (i = 0; i < graph->nvtxs; i++) {
     93:       PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "%" PetscInt_FMT ":\n", i));
     94:       PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "   which_dof: %" PetscInt_FMT "\n", graph->nodes[i].which_dof));
     95:       PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "   special_dof: %" PetscInt_FMT "\n", graph->nodes[i].special_dof));
     96:       PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "   shared by: %" PetscInt_FMT "\n", graph->nodes[i].count));
     97:       PetscCall(PetscViewerASCIIUseTabs(viewer, PETSC_FALSE));
     98:       if (graph->nodes[i].count) {
     99:         PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "     set of neighbours:"));
    100:         for (j = 0; j < graph->nodes[i].count; j++) PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, " %" PetscInt_FMT, graph->nodes[i].neighbours_set[j]));
    101:         PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "\n"));
    102:       }
    103:       PetscCall(PetscViewerASCIISetTab(viewer, tabs));
    104:       PetscCall(PetscViewerASCIIUseTabs(viewer, PETSC_TRUE));
    105:       PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "   number of local groups: %" PetscInt_FMT "\n", graph->nodes[i].local_groups_count));
    106:       PetscCall(PetscViewerASCIIUseTabs(viewer, PETSC_FALSE));
    107:       if (graph->nodes[i].local_groups_count) {
    108:         PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "     groups:"));
    109:         for (j = 0; j < graph->nodes[i].local_groups_count; j++) PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, " %" PetscInt_FMT, graph->nodes[i].local_groups[j]));
    110:         PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "\n"));
    111:       }
    112:       PetscCall(PetscViewerASCIISetTab(viewer, tabs));
    113:       PetscCall(PetscViewerASCIIUseTabs(viewer, PETSC_TRUE));

    115:       if (verbosity_level > 3) {
    116:         if (graph->xadj) {
    117:           PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "   local adj list:"));
    118:           PetscCall(PetscViewerASCIIUseTabs(viewer, PETSC_FALSE));
    119:           for (j = graph->xadj[i]; j < graph->xadj[i + 1]; j++) PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, " %" PetscInt_FMT, graph->adjncy[j]));
    120:           PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "\n"));
    121:           PetscCall(PetscViewerASCIISetTab(viewer, tabs));
    122:           PetscCall(PetscViewerASCIIUseTabs(viewer, PETSC_TRUE));
    123:         } else {
    124:           PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "   no adj info\n"));
    125:         }
    126:       }
    127:       if (graph->n_local_subs) PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "   local sub id: %" PetscInt_FMT "\n", graph->local_subs[i]));
    128:       PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "   interface subset id: %" PetscInt_FMT "\n", graph->nodes[i].subset));
    129:       if (graph->nodes[i].subset && graph->subset_ncc) PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "   ncc for subset: %" PetscInt_FMT "\n", graph->subset_ncc[graph->nodes[i].subset - 1]));
    130:     }
    131:   }
    132:   PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "Total number of connected components %" PetscInt_FMT "\n", graph->ncc));
    133:   PetscCall(PetscMalloc1(graph->cptr[graph->ncc], &queue_in_global_numbering));
    134:   PetscCall(ISLocalToGlobalMappingApply(graph->l2gmap, graph->cptr[graph->ncc], graph->queue, queue_in_global_numbering));
    135:   for (i = 0; i < graph->ncc; i++) {
    136:     PetscInt  node_num = graph->queue[graph->cptr[i]];
    137:     PetscBool printcc  = PETSC_FALSE;
    138:     PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "  cc %" PetscInt_FMT " (size %" PetscInt_FMT ", fid %" PetscInt_FMT ", neighs:", i, graph->cptr[i + 1] - graph->cptr[i], graph->nodes[node_num].which_dof));
    139:     PetscCall(PetscViewerASCIIUseTabs(viewer, PETSC_FALSE));
    140:     for (j = 0; j < graph->nodes[node_num].count; j++) PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, " %" PetscInt_FMT, graph->nodes[node_num].neighbours_set[j]));
    141:     if (verbosity_level > 1) {
    142:       PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "):"));
    143:       if (verbosity_level > 2 || graph->twodim || graph->nodes[node_num].count > 2 || (graph->nodes[node_num].count == 2 && graph->nodes[node_num].special_dof == PCBDDCGRAPH_NEUMANN_MARK)) printcc = PETSC_TRUE;
    144:       if (printcc) {
    145:         for (j = graph->cptr[i]; j < graph->cptr[i + 1]; j++) PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, " %" PetscInt_FMT " (%" PetscInt_FMT ")", graph->queue[j], queue_in_global_numbering[j]));
    146:       }
    147:     } else {
    148:       PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, ")"));
    149:     }
    150:     PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "\n"));
    151:     PetscCall(PetscViewerASCIISetTab(viewer, tabs));
    152:     PetscCall(PetscViewerASCIIUseTabs(viewer, PETSC_TRUE));
    153:   }
    154:   PetscCall(PetscFree(queue_in_global_numbering));
    155:   PetscCall(PetscViewerFlush(viewer));
    156:   PetscFunctionReturn(PETSC_SUCCESS);
    157: }

    159: PetscErrorCode PCBDDCGraphRestoreCandidatesIS(PCBDDCGraph graph, PetscInt *n_faces, IS *FacesIS[], PetscInt *n_edges, IS *EdgesIS[], IS *VerticesIS)
    160: {
    161:   PetscInt       i;
    162:   PetscContainer gcand;

    164:   PetscFunctionBegin;
    165:   PetscCall(PetscObjectQuery((PetscObject)graph->l2gmap, "_PCBDDCGraphCandidatesIS", (PetscObject *)&gcand));
    166:   if (gcand) {
    167:     if (n_faces) *n_faces = 0;
    168:     if (n_edges) *n_edges = 0;
    169:     if (FacesIS) *FacesIS = NULL;
    170:     if (EdgesIS) *EdgesIS = NULL;
    171:     if (VerticesIS) *VerticesIS = NULL;
    172:   }
    173:   if (n_faces) {
    174:     if (FacesIS) {
    175:       for (i = 0; i < *n_faces; i++) PetscCall(ISDestroy(&(*FacesIS)[i]));
    176:       PetscCall(PetscFree(*FacesIS));
    177:     }
    178:     *n_faces = 0;
    179:   }
    180:   if (n_edges) {
    181:     if (EdgesIS) {
    182:       for (i = 0; i < *n_edges; i++) PetscCall(ISDestroy(&(*EdgesIS)[i]));
    183:       PetscCall(PetscFree(*EdgesIS));
    184:     }
    185:     *n_edges = 0;
    186:   }
    187:   if (VerticesIS) PetscCall(ISDestroy(VerticesIS));
    188:   PetscFunctionReturn(PETSC_SUCCESS);
    189: }

    191: PetscErrorCode PCBDDCGraphGetCandidatesIS(PCBDDCGraph graph, PetscInt *n_faces, IS *FacesIS[], PetscInt *n_edges, IS *EdgesIS[], IS *VerticesIS)
    192: {
    193:   IS            *ISForFaces, *ISForEdges, ISForVertices;
    194:   PetscInt       i, nfc, nec, nvc, *idx, *mark;
    195:   PetscContainer gcand;

    197:   PetscFunctionBegin;
    198:   PetscCall(PetscObjectQuery((PetscObject)graph->l2gmap, "_PCBDDCGraphCandidatesIS", (PetscObject *)&gcand));
    199:   if (gcand) {
    200:     PCBDDCGraphCandidates cand;

    202:     PetscCall(PetscContainerGetPointer(gcand, (void **)&cand));
    203:     if (n_faces) *n_faces = cand->nfc;
    204:     if (FacesIS) *FacesIS = cand->Faces;
    205:     if (n_edges) *n_edges = cand->nec;
    206:     if (EdgesIS) *EdgesIS = cand->Edges;
    207:     if (VerticesIS) *VerticesIS = cand->Vertices;
    208:     PetscFunctionReturn(PETSC_SUCCESS);
    209:   }
    210:   PetscCall(PetscCalloc1(graph->ncc, &mark));
    211:   /* loop on ccs to evaluate number of faces, edges and vertices */
    212:   nfc = 0;
    213:   nec = 0;
    214:   nvc = 0;
    215:   for (i = 0; i < graph->ncc; i++) {
    216:     PetscInt repdof = graph->queue[graph->cptr[i]];
    217:     if (graph->cptr[i + 1] - graph->cptr[i] > graph->custom_minimal_size && graph->nodes[repdof].count <= graph->maxcount) {
    218:       if (!graph->twodim && graph->nodes[repdof].count == 2 && graph->nodes[repdof].special_dof != PCBDDCGRAPH_NEUMANN_MARK) {
    219:         nfc++;
    220:         mark[i] = 2;
    221:       } else {
    222:         nec++;
    223:         mark[i] = 1;
    224:       }
    225:     } else {
    226:       nvc += graph->cptr[i + 1] - graph->cptr[i];
    227:     }
    228:   }

    230:   /* allocate IS arrays for faces, edges. Vertices need a single index set. */
    231:   if (FacesIS) PetscCall(PetscMalloc1(nfc, &ISForFaces));
    232:   if (EdgesIS) PetscCall(PetscMalloc1(nec, &ISForEdges));
    233:   if (VerticesIS) PetscCall(PetscMalloc1(nvc, &idx));

    235:   /* loop on ccs to compute index sets for faces and edges */
    236:   if (!graph->queue_sorted) {
    237:     PetscInt *queue_global;

    239:     PetscCall(PetscMalloc1(graph->cptr[graph->ncc], &queue_global));
    240:     PetscCall(ISLocalToGlobalMappingApply(graph->l2gmap, graph->cptr[graph->ncc], graph->queue, queue_global));
    241:     for (i = 0; i < graph->ncc; i++) PetscCall(PetscSortIntWithArray(graph->cptr[i + 1] - graph->cptr[i], &queue_global[graph->cptr[i]], &graph->queue[graph->cptr[i]]));
    242:     PetscCall(PetscFree(queue_global));
    243:     graph->queue_sorted = PETSC_TRUE;
    244:   }
    245:   nfc = 0;
    246:   nec = 0;
    247:   for (i = 0; i < graph->ncc; i++) {
    248:     if (mark[i] == 2) {
    249:       if (FacesIS) PetscCall(ISCreateGeneral(PETSC_COMM_SELF, graph->cptr[i + 1] - graph->cptr[i], &graph->queue[graph->cptr[i]], PETSC_USE_POINTER, &ISForFaces[nfc]));
    250:       nfc++;
    251:     } else if (mark[i] == 1) {
    252:       if (EdgesIS) PetscCall(ISCreateGeneral(PETSC_COMM_SELF, graph->cptr[i + 1] - graph->cptr[i], &graph->queue[graph->cptr[i]], PETSC_USE_POINTER, &ISForEdges[nec]));
    253:       nec++;
    254:     }
    255:   }

    257:   /* index set for vertices */
    258:   if (VerticesIS) {
    259:     nvc = 0;
    260:     for (i = 0; i < graph->ncc; i++) {
    261:       if (!mark[i]) {
    262:         PetscInt j;

    264:         for (j = graph->cptr[i]; j < graph->cptr[i + 1]; j++) {
    265:           idx[nvc] = graph->queue[j];
    266:           nvc++;
    267:         }
    268:       }
    269:     }
    270:     /* sort vertex set (by local ordering) */
    271:     PetscCall(PetscSortInt(nvc, idx));
    272:     PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nvc, idx, PETSC_OWN_POINTER, &ISForVertices));
    273:   }
    274:   PetscCall(PetscFree(mark));

    276:   /* get back info */
    277:   if (n_faces) *n_faces = nfc;
    278:   if (FacesIS) *FacesIS = ISForFaces;
    279:   if (n_edges) *n_edges = nec;
    280:   if (EdgesIS) *EdgesIS = ISForEdges;
    281:   if (VerticesIS) *VerticesIS = ISForVertices;
    282:   PetscFunctionReturn(PETSC_SUCCESS);
    283: }

    285: PetscErrorCode PCBDDCGraphComputeConnectedComponents(PCBDDCGraph graph)
    286: {
    287:   PetscBool adapt_interface;
    288:   MPI_Comm  interface_comm;
    289:   PetscBT   cornerp = NULL;

    291:   PetscFunctionBegin;
    292:   PetscCall(PetscObjectGetComm((PetscObject)graph->l2gmap, &interface_comm));
    293:   /* compute connected components locally */
    294:   PetscCall(PCBDDCGraphComputeConnectedComponentsLocal(graph));
    295:   if (graph->seq_graph) PetscFunctionReturn(PETSC_SUCCESS);

    297:   if (graph->active_coords && !graph->multi_element) { /* face based corner selection XXX multi_element */
    298:     PetscBT    excluded;
    299:     PetscReal *wdist;
    300:     PetscInt   n_neigh, *neigh, *n_shared, **shared;
    301:     PetscInt   maxc, ns;

    303:     PetscCall(PetscBTCreate(graph->nvtxs, &cornerp));
    304:     PetscCall(ISLocalToGlobalMappingGetInfo(graph->l2gmap, &n_neigh, &neigh, &n_shared, &shared));
    305:     for (ns = 1, maxc = 0; ns < n_neigh; ns++) maxc = PetscMax(maxc, n_shared[ns]);
    306:     PetscCall(PetscMalloc1(maxc * graph->cdim, &wdist));
    307:     PetscCall(PetscBTCreate(maxc, &excluded));

    309:     for (ns = 1; ns < n_neigh; ns++) { /* first proc is self */
    310:       PetscReal *anchor, mdist;
    311:       PetscInt   fst, j, k, d, cdim = graph->cdim, n = n_shared[ns];
    312:       PetscInt   point1, point2, point3, point4;

    314:       /* import coordinates on shared interface */
    315:       PetscCall(PetscBTMemzero(n, excluded));
    316:       for (j = 0, fst = -1, k = 0; j < n; j++) {
    317:         PetscBool skip = PETSC_FALSE;
    318:         for (d = 0; d < cdim; d++) {
    319:           PetscReal c = graph->coords[shared[ns][j] * cdim + d];
    320:           skip        = (PetscBool)(skip || c == PETSC_MAX_REAL);
    321:           wdist[k++]  = c;
    322:         }
    323:         if (skip) PetscCall(PetscBTSet(excluded, j));
    324:         else if (fst == -1) fst = j;
    325:       }
    326:       if (fst == -1) continue;

    328:       /* the dofs are sorted by global numbering, so each rank starts from the same id
    329:          and it will detect the same corners from the given set */

    331:       /* find the farthest point from the starting one */
    332:       anchor = wdist + fst * cdim;
    333:       mdist  = -1.0;
    334:       point1 = fst;
    335:       for (j = fst; j < n; j++) {
    336:         PetscReal dist = 0.0;

    338:         if (PetscUnlikely(PetscBTLookup(excluded, j))) continue;
    339:         for (d = 0; d < cdim; d++) dist += (wdist[j * cdim + d] - anchor[d]) * (wdist[j * cdim + d] - anchor[d]);
    340:         if (dist > mdist) {
    341:           mdist  = dist;
    342:           point1 = j;
    343:         }
    344:       }

    346:       /* find the farthest point from point1 */
    347:       anchor = wdist + point1 * cdim;
    348:       mdist  = -1.0;
    349:       point2 = point1;
    350:       for (j = fst; j < n; j++) {
    351:         PetscReal dist = 0.0;

    353:         if (PetscUnlikely(PetscBTLookup(excluded, j))) continue;
    354:         for (d = 0; d < cdim; d++) dist += (wdist[j * cdim + d] - anchor[d]) * (wdist[j * cdim + d] - anchor[d]);
    355:         if (dist > mdist) {
    356:           mdist  = dist;
    357:           point2 = j;
    358:         }
    359:       }

    361:       /* find the third point maximizing the triangle area */
    362:       point3 = point2;
    363:       if (cdim > 2) {
    364:         PetscReal a = 0.0;

    366:         for (d = 0; d < cdim; d++) a += (wdist[point1 * cdim + d] - wdist[point2 * cdim + d]) * (wdist[point1 * cdim + d] - wdist[point2 * cdim + d]);
    367:         a     = PetscSqrtReal(a);
    368:         mdist = -1.0;
    369:         for (j = fst; j < n; j++) {
    370:           PetscReal area, b = 0.0, c = 0.0, s;

    372:           if (PetscUnlikely(PetscBTLookup(excluded, j))) continue;
    373:           for (d = 0; d < cdim; d++) {
    374:             b += (wdist[point1 * cdim + d] - wdist[j * cdim + d]) * (wdist[point1 * cdim + d] - wdist[j * cdim + d]);
    375:             c += (wdist[point2 * cdim + d] - wdist[j * cdim + d]) * (wdist[point2 * cdim + d] - wdist[j * cdim + d]);
    376:           }
    377:           b = PetscSqrtReal(b);
    378:           c = PetscSqrtReal(c);
    379:           s = 0.5 * (a + b + c);

    381:           /* Heron's formula, area squared */
    382:           area = s * (s - a) * (s - b) * (s - c);
    383:           if (area > mdist) {
    384:             mdist  = area;
    385:             point3 = j;
    386:           }
    387:         }
    388:       }

    390:       /* find the farthest point from point3 different from point1 and point2 */
    391:       anchor = wdist + point3 * cdim;
    392:       mdist  = -1.0;
    393:       point4 = point3;
    394:       for (j = fst; j < n; j++) {
    395:         PetscReal dist = 0.0;

    397:         if (PetscUnlikely(PetscBTLookup(excluded, j)) || j == point1 || j == point2 || j == point3) continue;
    398:         for (d = 0; d < cdim; d++) dist += (wdist[j * cdim + d] - anchor[d]) * (wdist[j * cdim + d] - anchor[d]);
    399:         if (dist > mdist) {
    400:           mdist  = dist;
    401:           point4 = j;
    402:         }
    403:       }

    405:       PetscCall(PetscBTSet(cornerp, shared[ns][point1]));
    406:       PetscCall(PetscBTSet(cornerp, shared[ns][point2]));
    407:       PetscCall(PetscBTSet(cornerp, shared[ns][point3]));
    408:       PetscCall(PetscBTSet(cornerp, shared[ns][point4]));

    410:       /* all dofs having the same coordinates will be primal */
    411:       for (j = fst; j < n; j++) {
    412:         PetscBool same[] = {PETSC_TRUE, PETSC_TRUE, PETSC_TRUE, PETSC_TRUE};

    414:         if (PetscUnlikely(PetscBTLookup(excluded, j))) continue;
    415:         for (d = 0; d < cdim; d++) {
    416:           same[0] = (PetscBool)(same[0] && (PetscAbsReal(wdist[j * cdim + d] - wdist[point1 * cdim + d]) < PETSC_SMALL));
    417:           same[1] = (PetscBool)(same[1] && (PetscAbsReal(wdist[j * cdim + d] - wdist[point2 * cdim + d]) < PETSC_SMALL));
    418:           same[2] = (PetscBool)(same[2] && (PetscAbsReal(wdist[j * cdim + d] - wdist[point3 * cdim + d]) < PETSC_SMALL));
    419:           same[3] = (PetscBool)(same[3] && (PetscAbsReal(wdist[j * cdim + d] - wdist[point4 * cdim + d]) < PETSC_SMALL));
    420:         }
    421:         if (same[0] || same[1] || same[2] || same[3]) PetscCall(PetscBTSet(cornerp, shared[ns][j]));
    422:       }
    423:     }
    424:     PetscCall(PetscBTDestroy(&excluded));
    425:     PetscCall(PetscFree(wdist));
    426:     PetscCall(ISLocalToGlobalMappingRestoreInfo(graph->l2gmap, &n_neigh, &neigh, &n_shared, &shared));
    427:   }

    429:   /* Adapt connected components if needed */
    430:   adapt_interface = (cornerp || graph->multi_element) ? PETSC_TRUE : PETSC_FALSE;
    431:   for (PetscInt i = 0; i < graph->n_subsets && !adapt_interface; i++) {
    432:     if (graph->subset_ncc[i] > 1) adapt_interface = PETSC_TRUE;
    433:   }
    434:   PetscCallMPI(MPIU_Allreduce(MPI_IN_PLACE, &adapt_interface, 1, MPI_C_BOOL, MPI_LOR, interface_comm));
    435:   if (adapt_interface) {
    436:     PetscSF         msf;
    437:     const PetscInt *n_ref_sharing;
    438:     PetscInt       *labels, *rootlabels, *mrlabels;
    439:     PetscInt        nr, nmr, nrs, ncc, cum_queue;

    441:     PetscCall(PetscMalloc1(graph->nvtxs, &labels));
    442:     PetscCall(PetscArrayzero(labels, graph->nvtxs));
    443:     for (PetscInt i = 0, k = 0; i < graph->ncc; i++) {
    444:       PetscInt s = 1;
    445:       for (PetscInt j = graph->cptr[i]; j < graph->cptr[i + 1]; j++) {
    446:         if (cornerp && PetscBTLookup(cornerp, graph->queue[j])) {
    447:           labels[graph->queue[j]] = -(k + s + 1);
    448:           s += 1;
    449:         } else {
    450:           labels[graph->queue[j]] = -(k + 1);
    451:         }
    452:       }
    453:       k += s;
    454:     }
    455:     PetscCall(PetscSFGetGraph(graph->interface_ref_sf, &nr, NULL, NULL, NULL));
    456:     PetscCall(PetscSFGetGraph(graph->interface_subset_sf, &nrs, NULL, NULL, NULL));
    457:     PetscCall(PetscSFGetMultiSF(graph->interface_subset_sf, &msf));
    458:     PetscCall(PetscSFGetGraph(msf, &nmr, NULL, NULL, NULL));
    459:     PetscCall(PetscCalloc2(nmr, &mrlabels, nrs, &rootlabels));

    461:     PetscCall(PetscSFComputeDegreeBegin(graph->interface_subset_sf, &n_ref_sharing));
    462:     PetscCall(PetscSFComputeDegreeEnd(graph->interface_subset_sf, &n_ref_sharing));
    463:     PetscCall(PetscSFGatherBegin(graph->interface_subset_sf, MPIU_INT, labels, mrlabels));
    464:     PetscCall(PetscSFGatherEnd(graph->interface_subset_sf, MPIU_INT, labels, mrlabels));

    466:     /* analyze contributions from processes
    467:        The structure of mrlabels is suitable to find intersections of ccs.
    468:        supposing the root subset has dimension 5 and leaves with labels:
    469:          0: [4 4 7 4 7], (2 connected components)
    470:          1: [3 2 2 3 2], (2 connected components)
    471:          2: [1 1 6 5 6], (3 connected components)
    472:        the multiroot data and the new labels corresponding to intersected connected components will be (column major)

    474:                   4 4 7 4 7
    475:        mrlabels   3 2 2 3 2
    476:                   1 1 6 5 6
    477:                   ---------
    478:        rootlabels 0 1 2 3 2
    479:     */
    480:     for (PetscInt i = 0, rcumlabels = 0, mcumlabels = 0; i < nr; i++) {
    481:       const PetscInt  subset_size    = graph->interface_ref_rsize[i];
    482:       const PetscInt *n_sharing      = n_ref_sharing + rcumlabels;
    483:       const PetscInt *mrbuffer       = mrlabels + mcumlabels;
    484:       PetscInt       *rbuffer        = rootlabels + rcumlabels;
    485:       PetscInt        subset_counter = 0;

    487:       for (PetscInt j = 0; j < subset_size; j++) {
    488:         if (!rbuffer[j]) { /* found a new cc  */
    489:           const PetscInt *jlabels = mrbuffer + j * n_sharing[0];
    490:           rbuffer[j]              = ++subset_counter;

    492:           for (PetscInt k = j + 1; k < subset_size; k++) { /* check for other nodes in new cc */
    493:             PetscBool       same_set = PETSC_TRUE;
    494:             const PetscInt *klabels  = mrbuffer + k * n_sharing[0];

    496:             for (PetscInt s = 0; s < n_sharing[0]; s++) {
    497:               if (jlabels[s] != klabels[s]) {
    498:                 same_set = PETSC_FALSE;
    499:                 break;
    500:               }
    501:             }
    502:             if (same_set) rbuffer[k] = subset_counter;
    503:           }
    504:         }
    505:       }
    506:       if (subset_size) {
    507:         rcumlabels += subset_size;
    508:         mcumlabels += n_sharing[0] * subset_size;
    509:       }
    510:     }

    512:     /* Now communicate the intersected labels */
    513:     PetscCall(PetscSFBcastBegin(graph->interface_subset_sf, MPIU_INT, rootlabels, labels, MPI_REPLACE));
    514:     PetscCall(PetscSFBcastEnd(graph->interface_subset_sf, MPIU_INT, rootlabels, labels, MPI_REPLACE));
    515:     PetscCall(PetscFree2(mrlabels, rootlabels));

    517:     /* and adapt local connected components */
    518:     PetscInt  *ocptr, *oqueue;
    519:     PetscBool *touched;

    521:     PetscCall(PetscMalloc3(graph->ncc + 1, &ocptr, graph->cptr[graph->ncc], &oqueue, graph->cptr[graph->ncc], &touched));
    522:     PetscCall(PetscArraycpy(ocptr, graph->cptr, graph->ncc + 1));
    523:     PetscCall(PetscArraycpy(oqueue, graph->queue, graph->cptr[graph->ncc]));
    524:     PetscCall(PetscArrayzero(touched, graph->cptr[graph->ncc]));

    526:     ncc       = 0;
    527:     cum_queue = 0;
    528:     for (PetscInt i = 0; i < graph->ncc; i++) {
    529:       for (PetscInt j = ocptr[i]; j < ocptr[i + 1]; j++) {
    530:         const PetscInt jlabel = labels[oqueue[j]];

    532:         if (jlabel) {
    533:           graph->cptr[ncc] = cum_queue;
    534:           ncc++;
    535:           for (PetscInt k = j; k < ocptr[i + 1]; k++) { /* check for other nodes in new cc */
    536:             if (labels[oqueue[k]] == jlabel) {
    537:               graph->queue[cum_queue++] = oqueue[k];
    538:               labels[oqueue[k]]         = 0;
    539:             }
    540:           }
    541:         }
    542:       }
    543:     }
    544:     PetscCall(PetscFree3(ocptr, oqueue, touched));
    545:     PetscCall(PetscFree(labels));
    546:     graph->cptr[ncc]    = cum_queue;
    547:     graph->queue_sorted = PETSC_FALSE;
    548:     graph->ncc          = ncc;
    549:   }
    550:   PetscCall(PetscBTDestroy(&cornerp));

    552:   /* Determine if we are in 2D or 3D */
    553:   if (!graph->twodimset) {
    554:     PetscBool twodim = PETSC_TRUE;
    555:     for (PetscInt i = 0; i < graph->ncc; i++) {
    556:       PetscInt repdof = graph->queue[graph->cptr[i]];
    557:       PetscInt ccsize = graph->cptr[i + 1] - graph->cptr[i];
    558:       if (graph->nodes[repdof].count > 2 && ccsize > graph->custom_minimal_size) {
    559:         twodim = PETSC_FALSE;
    560:         break;
    561:       }
    562:     }
    563:     PetscCallMPI(MPIU_Allreduce(&twodim, &graph->twodim, 1, MPI_C_BOOL, MPI_LAND, PetscObjectComm((PetscObject)graph->l2gmap)));
    564:     graph->twodimset = PETSC_TRUE;
    565:   }
    566:   PetscFunctionReturn(PETSC_SUCCESS);
    567: }

    569: static inline PetscErrorCode PCBDDCGraphComputeCC_Private(PCBDDCGraph graph, PetscInt pid, PetscInt *PETSC_RESTRICT queue_tip, PetscInt n_prev, PetscInt *n_added)
    570: {
    571:   PetscInt i, j, n = 0;

    573:   const PetscInt *PETSC_RESTRICT xadj        = graph->xadj;
    574:   const PetscInt *PETSC_RESTRICT adjncy      = graph->adjncy;
    575:   const PetscInt *PETSC_RESTRICT subset_idxs = graph->subset_idxs[pid - 1];
    576:   const PetscInt *PETSC_RESTRICT local_subs  = graph->local_subs;
    577:   const PetscInt                 subset_size = graph->subset_size[pid - 1];

    579:   PCBDDCGraphNode *PETSC_RESTRICT nodes = graph->nodes;

    581:   const PetscBool havecsr  = (PetscBool)(!!xadj);
    582:   const PetscBool havesubs = (PetscBool)(!!graph->n_local_subs);

    584:   PetscFunctionBegin;
    585:   if (havecsr && !havesubs) {
    586:     for (i = -n_prev; i < 0; i++) {
    587:       const PetscInt start_dof = queue_tip[i];

    589:       /* we assume that if a dof has a size 1 adjacency list and the corresponding entry is negative, it is connected to all dofs */
    590:       if (xadj[start_dof + 1] - xadj[start_dof] == 1 && adjncy[xadj[start_dof]] < 0) {
    591:         for (j = 0; j < subset_size; j++) { /* pid \in [1,graph->n_subsets] */
    592:           const PetscInt dof = subset_idxs[j];

    594:           if (!nodes[dof].touched && nodes[dof].subset == pid) {
    595:             nodes[dof].touched = PETSC_TRUE;
    596:             queue_tip[n]       = dof;
    597:             n++;
    598:           }
    599:         }
    600:       } else {
    601:         for (j = xadj[start_dof]; j < xadj[start_dof + 1]; j++) {
    602:           const PetscInt dof = adjncy[j];

    604:           if (!nodes[dof].touched && nodes[dof].subset == pid) {
    605:             nodes[dof].touched = PETSC_TRUE;
    606:             queue_tip[n]       = dof;
    607:             n++;
    608:           }
    609:         }
    610:       }
    611:     }
    612:   } else if (havecsr && havesubs) {
    613:     const PetscInt sid = local_subs[queue_tip[-n_prev]];

    615:     for (i = -n_prev; i < 0; i++) {
    616:       const PetscInt start_dof = queue_tip[i];

    618:       /* we assume that if a dof has a size 1 adjacency list and the corresponding entry is negative, it is connected to all dofs belonging to the local sub */
    619:       if (xadj[start_dof + 1] - xadj[start_dof] == 1 && adjncy[xadj[start_dof]] < 0) {
    620:         for (j = 0; j < subset_size; j++) { /* pid \in [1,graph->n_subsets] */
    621:           const PetscInt dof = subset_idxs[j];

    623:           if (!nodes[dof].touched && nodes[dof].subset == pid && local_subs[dof] == sid) {
    624:             nodes[dof].touched = PETSC_TRUE;
    625:             queue_tip[n]       = dof;
    626:             n++;
    627:           }
    628:         }
    629:       } else {
    630:         for (j = xadj[start_dof]; j < xadj[start_dof + 1]; j++) {
    631:           const PetscInt dof = adjncy[j];

    633:           if (!nodes[dof].touched && nodes[dof].subset == pid && local_subs[dof] == sid) {
    634:             nodes[dof].touched = PETSC_TRUE;
    635:             queue_tip[n]       = dof;
    636:             n++;
    637:           }
    638:         }
    639:       }
    640:     }
    641:   } else if (havesubs) { /* sub info only */
    642:     const PetscInt sid = local_subs[queue_tip[-n_prev]];

    644:     for (j = 0; j < subset_size; j++) { /* pid \in [1,graph->n_subsets] */
    645:       const PetscInt dof = subset_idxs[j];

    647:       if (!nodes[dof].touched && nodes[dof].subset == pid && local_subs[dof] == sid) {
    648:         nodes[dof].touched = PETSC_TRUE;
    649:         queue_tip[n]       = dof;
    650:         n++;
    651:       }
    652:     }
    653:   } else {
    654:     for (j = 0; j < subset_size; j++) { /* pid \in [1,graph->n_subsets] */
    655:       const PetscInt dof = subset_idxs[j];

    657:       if (!nodes[dof].touched && nodes[dof].subset == pid) {
    658:         nodes[dof].touched = PETSC_TRUE;
    659:         queue_tip[n]       = dof;
    660:         n++;
    661:       }
    662:     }
    663:   }
    664:   *n_added = n;
    665:   PetscFunctionReturn(PETSC_SUCCESS);
    666: }

    668: PetscErrorCode PCBDDCGraphComputeConnectedComponentsLocal(PCBDDCGraph graph)
    669: {
    670:   PetscInt ncc, cum_queue;

    672:   PetscFunctionBegin;
    673:   PetscCheck(graph->setupcalled, PetscObjectComm((PetscObject)graph->l2gmap), PETSC_ERR_ORDER, "PCBDDCGraphSetUp should be called first");
    674:   /* quiet return if there isn't any local info */
    675:   if (!graph->xadj && !graph->n_local_subs) PetscFunctionReturn(PETSC_SUCCESS);

    677:   /* reset any previous search of connected components */
    678:   for (PetscInt i = 0; i < graph->nvtxs; i++) graph->nodes[i].touched = PETSC_FALSE;
    679:   if (!graph->seq_graph) {
    680:     for (PetscInt i = 0; i < graph->nvtxs; i++) {
    681:       if (graph->nodes[i].special_dof == PCBDDCGRAPH_DIRICHLET_MARK || graph->nodes[i].count < 2) graph->nodes[i].touched = PETSC_TRUE;
    682:     }
    683:   }

    685:   /* begin search for connected components */
    686:   cum_queue = 0;
    687:   ncc       = 0;
    688:   for (PetscInt n = 0; n < graph->n_subsets; n++) {
    689:     const PetscInt *subset_idxs = graph->subset_idxs[n];
    690:     const PetscInt  pid         = n + 1; /* partition labeled by 0 is discarded */

    692:     PetscInt found = 0, prev = 0, first = 0, ncc_pid = 0;

    694:     while (found != graph->subset_size[n]) {
    695:       PetscInt added = 0;

    697:       if (!prev) { /* search for new starting dof */
    698:         while (graph->nodes[subset_idxs[first]].touched) first++;
    699:         graph->nodes[subset_idxs[first]].touched = PETSC_TRUE;
    700:         graph->queue[cum_queue]                  = subset_idxs[first];
    701:         graph->cptr[ncc]                         = cum_queue;
    702:         prev                                     = 1;
    703:         cum_queue++;
    704:         found++;
    705:         ncc_pid++;
    706:         ncc++;
    707:       }
    708:       PetscCall(PCBDDCGraphComputeCC_Private(graph, pid, graph->queue + cum_queue, prev, &added));
    709:       if (!added) {
    710:         graph->subset_ncc[n] = ncc_pid;
    711:         graph->cptr[ncc]     = cum_queue;
    712:       }
    713:       prev = added;
    714:       found += added;
    715:       cum_queue += added;
    716:       if (added && found == graph->subset_size[n]) {
    717:         graph->subset_ncc[n] = ncc_pid;
    718:         graph->cptr[ncc]     = cum_queue;
    719:       }
    720:     }
    721:   }
    722:   graph->ncc          = ncc;
    723:   graph->queue_sorted = PETSC_FALSE;
    724:   PetscFunctionReturn(PETSC_SUCCESS);
    725: }

    727: PetscErrorCode PCBDDCGraphSetUp(PCBDDCGraph graph, PetscInt custom_minimal_size, IS neumann_is, IS dirichlet_is, PetscInt n_ISForDofs, IS ISForDofs[], IS custom_primal_vertices)
    728: {
    729:   IS                       subset;
    730:   MPI_Comm                 comm;
    731:   PetscHMapPCBDDCGraphNode subsetmaps;
    732:   const PetscInt          *is_indices;
    733:   PetscInt                *queue_global, *nodecount, **nodeneighs, *subset_sizes;
    734:   PetscInt                 i, j, k, nodes_touched, is_size, nvtxs = graph->nvtxs;
    735:   PetscMPIInt              size, rank;

    737:   PetscFunctionBegin;
    739:   if (neumann_is) {
    741:     PetscCheckSameComm(graph->l2gmap, 1, neumann_is, 3);
    742:   }
    743:   graph->has_dirichlet = PETSC_FALSE;
    744:   if (dirichlet_is) {
    746:     PetscCheckSameComm(graph->l2gmap, 1, dirichlet_is, 4);
    747:     graph->has_dirichlet = PETSC_TRUE;
    748:   }
    750:   for (i = 0; i < n_ISForDofs; i++) {
    752:     PetscCheckSameComm(graph->l2gmap, 1, ISForDofs[i], 6);
    753:   }
    754:   if (custom_primal_vertices) {
    756:     PetscCheckSameComm(graph->l2gmap, 1, custom_primal_vertices, 7);
    757:   }
    758:   for (i = 0; i < nvtxs; i++) graph->nodes[i].touched = PETSC_FALSE;

    760:   PetscCall(PetscObjectGetComm((PetscObject)graph->l2gmap, &comm));
    761:   PetscCallMPI(MPI_Comm_size(comm, &size));
    762:   PetscCallMPI(MPI_Comm_rank(comm, &rank));

    764:   /* custom_minimal_size */
    765:   graph->custom_minimal_size = custom_minimal_size;

    767:   /* get node info from l2gmap */
    768:   PetscCall(ISLocalToGlobalMappingGetNodeInfo(graph->l2gmap, NULL, &nodecount, &nodeneighs));

    770:   /* Allocate space for storing the set of neighbours for each node */
    771:   graph->multi_element = PETSC_FALSE;
    772:   for (i = 0; i < nvtxs; i++) {
    773:     graph->nodes[i].count = nodecount[i];
    774:     if (!graph->seq_graph) {
    775:       PetscCall(PetscMalloc1(nodecount[i], &graph->nodes[i].neighbours_set));
    776:       PetscCall(PetscArraycpy(graph->nodes[i].neighbours_set, nodeneighs[i], nodecount[i]));

    778:       if (!graph->multi_element) {
    779:         PetscInt nself;
    780:         for (j = 0, nself = 0; j < graph->nodes[i].count; j++)
    781:           if (graph->nodes[i].neighbours_set[j] == rank) nself++;
    782:         if (nself > 1) graph->multi_element = PETSC_TRUE;
    783:       }
    784:     } else {
    785:       PetscCall(PetscCalloc1(nodecount[i], &graph->nodes[i].neighbours_set));
    786:     }
    787:   }
    788:   PetscCall(ISLocalToGlobalMappingRestoreNodeInfo(graph->l2gmap, NULL, &nodecount, &nodeneighs));
    789:   PetscCallMPI(MPIU_Allreduce(MPI_IN_PLACE, &graph->multi_element, 1, MPI_C_BOOL, MPI_LOR, comm));

    791:   /* compute local groups */
    792:   if (graph->multi_element) {
    793:     const PetscInt *idxs, *indegree;
    794:     IS              is, lis;
    795:     PetscLayout     layout;
    796:     PetscSF         sf, multisf;
    797:     PetscInt        n, nmulti, c, *multi_root_subs, *start;

    799:     PetscCheck(!nvtxs || graph->local_subs, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing local subdomain information");

    801:     PetscCall(ISLocalToGlobalMappingGetIndices(graph->l2gmap, &idxs));
    802:     PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nvtxs, idxs, PETSC_USE_POINTER, &is));
    803:     PetscCall(ISRenumber(is, NULL, &n, &lis));
    804:     PetscCall(ISDestroy(&is));

    806:     PetscCall(ISLocalToGlobalMappingRestoreIndices(graph->l2gmap, &idxs));
    807:     PetscCall(ISGetIndices(lis, &idxs));
    808:     PetscCall(PetscLayoutCreate(PETSC_COMM_SELF, &layout));
    809:     PetscCall(PetscLayoutSetSize(layout, n));
    810:     PetscCall(PetscSFCreate(PETSC_COMM_SELF, &sf));
    811:     PetscCall(PetscSFSetGraphLayout(sf, layout, nvtxs, NULL, PETSC_OWN_POINTER, idxs));
    812:     PetscCall(PetscLayoutDestroy(&layout));
    813:     PetscCall(PetscSFGetMultiSF(sf, &multisf));
    814:     PetscCall(PetscSFComputeDegreeBegin(sf, &indegree));
    815:     PetscCall(PetscSFComputeDegreeEnd(sf, &indegree));
    816:     PetscCall(PetscSFGetGraph(multisf, &nmulti, NULL, NULL, NULL));
    817:     PetscCall(PetscMalloc2(nmulti, &multi_root_subs, n + 1, &start));
    818:     start[0] = 0;
    819:     for (i = 0; i < n; i++) start[i + 1] = start[i] + indegree[i];
    820:     PetscCall(PetscSFGatherBegin(sf, MPIU_INT, graph->local_subs, multi_root_subs));
    821:     PetscCall(PetscSFGatherEnd(sf, MPIU_INT, graph->local_subs, multi_root_subs));
    822:     for (i = 0; i < nvtxs; i++) {
    823:       PetscInt gid = idxs[i];

    825:       graph->nodes[i].local_sub = graph->local_subs[i];
    826:       for (j = 0, c = 0; j < graph->nodes[i].count; j++) {
    827:         if (graph->nodes[i].neighbours_set[j] == rank) c++;
    828:       }
    829:       PetscCheck(c == indegree[idxs[i]], PETSC_COMM_SELF, PETSC_ERR_PLIB, "%" PetscInt_FMT " != %" PetscInt_FMT, c, indegree[idxs[i]]);
    830:       PetscCall(PetscMalloc1(c, &graph->nodes[i].local_groups));
    831:       for (j = 0; j < c; j++) graph->nodes[i].local_groups[j] = multi_root_subs[start[gid] + j];
    832:       PetscCall(PetscSortInt(c, graph->nodes[i].local_groups));
    833:       graph->nodes[i].local_groups_count = c;
    834:     }
    835:     PetscCall(PetscFree2(multi_root_subs, start));
    836:     PetscCall(ISRestoreIndices(lis, &idxs));
    837:     PetscCall(ISDestroy(&lis));
    838:     PetscCall(PetscSFDestroy(&sf));
    839:   }

    841:   /*
    842:      Get info for dofs splitting
    843:      User can specify just a subset; an additional field is considered as a complementary field
    844:   */
    845:   for (i = 0, k = 0; i < n_ISForDofs; i++) {
    846:     PetscInt bs;

    848:     PetscCall(ISGetBlockSize(ISForDofs[i], &bs));
    849:     k += bs;
    850:   }
    851:   for (i = 0; i < nvtxs; i++) graph->nodes[i].which_dof = k; /* by default a dof belongs to the complement set */
    852:   for (i = 0, k = 0; i < n_ISForDofs; i++) {
    853:     PetscInt bs;

    855:     PetscCall(ISGetLocalSize(ISForDofs[i], &is_size));
    856:     PetscCall(ISGetBlockSize(ISForDofs[i], &bs));
    857:     PetscCall(ISGetIndices(ISForDofs[i], &is_indices));
    858:     for (j = 0; j < is_size / bs; j++) {
    859:       PetscInt b;

    861:       for (b = 0; b < bs; b++) {
    862:         PetscInt jj = bs * j + b;

    864:         if (is_indices[jj] > -1 && is_indices[jj] < nvtxs) { /* out of bounds indices (if any) are skipped */
    865:           graph->nodes[is_indices[jj]].which_dof = k + b;
    866:         }
    867:       }
    868:     }
    869:     PetscCall(ISRestoreIndices(ISForDofs[i], &is_indices));
    870:     k += bs;
    871:   }

    873:   /* Take into account Neumann nodes */
    874:   if (neumann_is) {
    875:     PetscCall(ISGetLocalSize(neumann_is, &is_size));
    876:     PetscCall(ISGetIndices(neumann_is, &is_indices));
    877:     for (i = 0; i < is_size; i++) {
    878:       if (is_indices[i] > -1 && is_indices[i] < nvtxs) { /* out of bounds indices (if any) are skipped */
    879:         graph->nodes[is_indices[i]].special_dof = PCBDDCGRAPH_NEUMANN_MARK;
    880:       }
    881:     }
    882:     PetscCall(ISRestoreIndices(neumann_is, &is_indices));
    883:   }

    885:   /* Take into account Dirichlet nodes (they overwrite any mark previously set) */
    886:   if (dirichlet_is) {
    887:     PetscCall(ISGetLocalSize(dirichlet_is, &is_size));
    888:     PetscCall(ISGetIndices(dirichlet_is, &is_indices));
    889:     for (i = 0; i < is_size; i++) {
    890:       if (is_indices[i] > -1 && is_indices[i] < nvtxs) { /* out of bounds indices (if any) are skipped */
    891:         if (!graph->seq_graph) {                         /* dirichlet nodes treated as internal */
    892:           graph->nodes[is_indices[i]].touched = PETSC_TRUE;
    893:           graph->nodes[is_indices[i]].subset  = 0;
    894:         }
    895:         graph->nodes[is_indices[i]].special_dof = PCBDDCGRAPH_DIRICHLET_MARK;
    896:       }
    897:     }
    898:     PetscCall(ISRestoreIndices(dirichlet_is, &is_indices));
    899:   }

    901:   /* mark special nodes (if any) -> each will become a single dof equivalence class (i.e. point constraint for BDDC) */
    902:   if (custom_primal_vertices) {
    903:     PetscCall(ISGetLocalSize(custom_primal_vertices, &is_size));
    904:     PetscCall(ISGetIndices(custom_primal_vertices, &is_indices));
    905:     for (i = 0, j = 0; i < is_size; i++) {
    906:       if (is_indices[i] > -1 && is_indices[i] < nvtxs && graph->nodes[is_indices[i]].special_dof != PCBDDCGRAPH_DIRICHLET_MARK) { /* out of bounds indices (if any) are skipped */
    907:         graph->nodes[is_indices[i]].special_dof = PCBDDCGRAPH_SPECIAL_MARK - j;
    908:         j++;
    909:       }
    910:     }
    911:     PetscCall(ISRestoreIndices(custom_primal_vertices, &is_indices));
    912:   }

    914:   /* mark interior nodes as touched and belonging to partition number 0 */
    915:   if (!graph->seq_graph) {
    916:     for (i = 0; i < nvtxs; i++) {
    917:       const PetscInt icount = graph->nodes[i].count;
    918:       if (graph->nodes[i].count < 2) {
    919:         graph->nodes[i].touched = PETSC_TRUE;
    920:         graph->nodes[i].subset  = 0;
    921:       } else {
    922:         if (graph->multi_element) {
    923:           graph->nodes[i].shared = PETSC_FALSE;
    924:           for (k = 0; k < icount; k++)
    925:             if (graph->nodes[i].neighbours_set[k] != rank) {
    926:               graph->nodes[i].shared = PETSC_TRUE;
    927:               break;
    928:             }
    929:         } else {
    930:           graph->nodes[i].shared = PETSC_TRUE;
    931:         }
    932:       }
    933:     }
    934:   } else {
    935:     for (i = 0; i < nvtxs; i++) graph->nodes[i].shared = PETSC_TRUE;
    936:   }

    938:   /* init graph structure and compute default subsets */
    939:   nodes_touched = 0;
    940:   for (i = 0; i < nvtxs; i++)
    941:     if (graph->nodes[i].touched) nodes_touched++;

    943:   /* allocated space for queues */
    944:   if (graph->seq_graph) {
    945:     PetscCall(PetscMalloc2(nvtxs + 1, &graph->cptr, nvtxs, &graph->queue));
    946:   } else {
    947:     PetscInt nused = nvtxs - nodes_touched;
    948:     PetscCall(PetscMalloc2(nused + 1, &graph->cptr, nused, &graph->queue));
    949:   }

    951:   graph->ncc = 0;
    952:   PetscCall(PetscHMapPCBDDCGraphNodeCreate(&subsetmaps));
    953:   PetscCall(PetscCalloc1(nvtxs, &subset_sizes));
    954:   for (i = 0; i < nvtxs; i++) {
    955:     PetscHashIter iter;
    956:     PetscBool     missing;
    957:     PetscInt      subset;

    959:     if (graph->nodes[i].touched) continue;
    960:     graph->nodes[i].touched = PETSC_TRUE;
    961:     PetscCall(PetscHMapPCBDDCGraphNodePut(subsetmaps, &graph->nodes[i], &iter, &missing));
    962:     if (missing) {
    963:       graph->ncc++;
    964:       PetscCall(PetscHMapPCBDDCGraphNodeIterSet(subsetmaps, iter, graph->ncc));
    965:       subset = graph->ncc;
    966:     } else PetscCall(PetscHMapPCBDDCGraphNodeIterGet(subsetmaps, iter, &subset));
    967:     subset_sizes[subset - 1] += 1;
    968:     graph->nodes[i].subset = subset;
    969:   }

    971:   graph->cptr[0] = 0;
    972:   for (i = 0; i < graph->ncc; i++) graph->cptr[i + 1] = graph->cptr[i] + subset_sizes[i];
    973:   for (i = 0; i < graph->ncc; i++) subset_sizes[i] = 0;

    975:   for (i = 0; i < nvtxs; i++) {
    976:     const PetscInt subset = graph->nodes[i].subset - 1;
    977:     if (subset < 0) continue;
    978:     PetscCheck(subset_sizes[subset] + graph->cptr[subset] < graph->cptr[subset + 1], PETSC_COMM_SELF, PETSC_ERR_PLIB, "Error for subset %" PetscInt_FMT, subset);
    979:     graph->queue[subset_sizes[subset] + graph->cptr[subset]] = i;
    980:     subset_sizes[subset] += 1;
    981:   }
    982:   for (i = 0; i < graph->ncc; i++) PetscCheck(subset_sizes[i] + graph->cptr[i] == graph->cptr[i + 1], PETSC_COMM_SELF, PETSC_ERR_PLIB, "Error for subset %" PetscInt_FMT, i);

    984:   PetscCall(PetscHMapPCBDDCGraphNodeDestroy(&subsetmaps));
    985:   PetscCall(PetscFree(subset_sizes));

    987:   /* set default number of subsets */
    988:   graph->n_subsets = graph->ncc;
    989:   PetscCall(PetscMalloc1(graph->n_subsets, &graph->subset_ncc));
    990:   for (i = 0; i < graph->n_subsets; i++) graph->subset_ncc[i] = 1;

    992:   PetscCall(PetscMalloc1(graph->ncc, &graph->subset_ref_node));
    993:   PetscCall(PetscMalloc1(graph->cptr[graph->ncc], &queue_global));
    994:   PetscCall(PetscMalloc2(graph->ncc, &graph->subset_size, graph->ncc, &graph->subset_idxs));
    995:   if (graph->multi_element) PetscCall(PetscMalloc1(graph->ncc, &graph->gsubset_size));
    996:   else graph->gsubset_size = graph->subset_size;
    997:   PetscCall(ISLocalToGlobalMappingApply(graph->l2gmap, graph->cptr[graph->ncc], graph->queue, queue_global));

    999:   PetscHMapI cnt_unique;

    1001:   PetscCall(PetscHMapICreate(&cnt_unique));
    1002:   for (j = 0; j < graph->ncc; j++) {
    1003:     PetscInt c = 0, ref_node = PETSC_INT_MAX;

    1005:     for (k = graph->cptr[j]; k < graph->cptr[j + 1]; k++) {
    1006:       ref_node = PetscMin(ref_node, queue_global[k]);
    1007:       if (graph->multi_element) {
    1008:         PetscBool     missing;
    1009:         PetscHashIter iter;

    1011:         PetscCall(PetscHMapIPut(cnt_unique, queue_global[k], &iter, &missing));
    1012:         if (missing) c++;
    1013:       }
    1014:     }
    1015:     graph->gsubset_size[j]    = c;
    1016:     graph->subset_size[j]     = graph->cptr[j + 1] - graph->cptr[j];
    1017:     graph->subset_ref_node[j] = ref_node;
    1018:     if (graph->multi_element) PetscCall(PetscHMapIClear(cnt_unique));
    1019:   }
    1020:   PetscCall(PetscHMapIDestroy(&cnt_unique));

    1022:   /* save information on subsets (needed when analyzing the connected components) */
    1023:   if (graph->ncc) {
    1024:     PetscCall(PetscMalloc1(graph->cptr[graph->ncc], &graph->subset_idxs[0]));
    1025:     PetscCall(PetscArrayzero(graph->subset_idxs[0], graph->cptr[graph->ncc]));
    1026:     for (j = 1; j < graph->ncc; j++) graph->subset_idxs[j] = graph->subset_idxs[j - 1] + graph->subset_size[j - 1];
    1027:     PetscCall(PetscArraycpy(graph->subset_idxs[0], graph->queue, graph->cptr[graph->ncc]));
    1028:   }

    1030:   /* check consistency and create SF to analyze components on the interface between subdomains */
    1031:   if (!graph->seq_graph) {
    1032:     PetscSF         msf;
    1033:     PetscLayout     map;
    1034:     const PetscInt *degree;
    1035:     PetscInt        nr, nmr, *rdata;
    1036:     PetscBool       valid = PETSC_TRUE;
    1037:     PetscInt        subset_N;
    1038:     IS              subset_n;
    1039:     const PetscInt *idxs;

    1041:     PetscCall(ISCreateGeneral(comm, graph->n_subsets, graph->subset_ref_node, PETSC_USE_POINTER, &subset));
    1042:     PetscCall(ISRenumber(subset, NULL, &subset_N, &subset_n));
    1043:     PetscCall(ISDestroy(&subset));

    1045:     PetscCall(PetscSFCreate(comm, &graph->interface_ref_sf));
    1046:     PetscCall(PetscLayoutCreateFromSizes(comm, PETSC_DECIDE, subset_N, 1, &map));
    1047:     PetscCall(ISGetIndices(subset_n, &idxs));
    1048:     PetscCall(PetscSFSetGraphLayout(graph->interface_ref_sf, map, graph->n_subsets, NULL, PETSC_OWN_POINTER, idxs));
    1049:     PetscCall(ISRestoreIndices(subset_n, &idxs));
    1050:     PetscCall(ISDestroy(&subset_n));
    1051:     PetscCall(PetscLayoutDestroy(&map));

    1053:     PetscCall(PetscSFComputeDegreeBegin(graph->interface_ref_sf, &degree));
    1054:     PetscCall(PetscSFComputeDegreeEnd(graph->interface_ref_sf, &degree));
    1055:     PetscCall(PetscSFGetMultiSF(graph->interface_ref_sf, &msf));
    1056:     PetscCall(PetscSFGetGraph(graph->interface_ref_sf, &nr, NULL, NULL, NULL));
    1057:     PetscCall(PetscSFGetGraph(msf, &nmr, NULL, NULL, NULL));
    1058:     PetscCall(PetscCalloc1(nmr, &rdata));
    1059:     PetscCall(PetscSFGatherBegin(graph->interface_ref_sf, MPIU_INT, graph->gsubset_size, rdata));
    1060:     PetscCall(PetscSFGatherEnd(graph->interface_ref_sf, MPIU_INT, graph->gsubset_size, rdata));
    1061:     for (PetscInt i = 0, c = 0; i < nr && valid; i++) {
    1062:       for (PetscInt j = 0; j < degree[i]; j++) {
    1063:         if (rdata[j + c] != rdata[c]) valid = PETSC_FALSE;
    1064:       }
    1065:       c += degree[i];
    1066:     }
    1067:     PetscCall(PetscFree(rdata));
    1068:     PetscCallMPI(MPIU_Allreduce(MPI_IN_PLACE, &valid, 1, MPI_C_BOOL, MPI_LAND, comm));
    1069:     PetscCheck(valid, comm, PETSC_ERR_PLIB, "Initial local subsets are not consistent");

    1071:     /* Now create SF with each root extended to gsubset_size roots */
    1072:     PetscInt           mss = 0;
    1073:     const PetscSFNode *subs_remote;

    1075:     PetscCall(PetscSFGetGraph(graph->interface_ref_sf, NULL, NULL, NULL, &subs_remote));
    1076:     for (PetscInt i = 0; i < graph->n_subsets; i++) mss = PetscMax(graph->subset_size[i], mss);

    1078:     PetscInt nri, nli, *start_rsize, *cum_rsize;
    1079:     PetscCall(PetscCalloc1(graph->n_subsets + 1, &start_rsize));
    1080:     PetscCall(PetscCalloc1(nr, &graph->interface_ref_rsize));
    1081:     PetscCall(PetscMalloc1(nr + 1, &cum_rsize));
    1082:     PetscCall(PetscSFReduceBegin(graph->interface_ref_sf, MPIU_INT, graph->gsubset_size, graph->interface_ref_rsize, MPI_REPLACE));
    1083:     PetscCall(PetscSFReduceEnd(graph->interface_ref_sf, MPIU_INT, graph->gsubset_size, graph->interface_ref_rsize, MPI_REPLACE));

    1085:     nri          = 0;
    1086:     cum_rsize[0] = 0;
    1087:     for (PetscInt i = 0; i < nr; i++) {
    1088:       nri += graph->interface_ref_rsize[i];
    1089:       cum_rsize[i + 1] = cum_rsize[i] + graph->interface_ref_rsize[i];
    1090:     }
    1091:     nli = graph->cptr[graph->ncc];
    1092:     PetscCall(PetscSFBcastBegin(graph->interface_ref_sf, MPIU_INT, cum_rsize, start_rsize, MPI_REPLACE));
    1093:     PetscCall(PetscSFBcastEnd(graph->interface_ref_sf, MPIU_INT, cum_rsize, start_rsize, MPI_REPLACE));
    1094:     PetscCall(PetscFree(cum_rsize));

    1096:     PetscInt    *ilocal, *queue_global_uniq;
    1097:     PetscSFNode *iremote;
    1098:     PetscBool   *touched;

    1100:     PetscCall(PetscSFCreate(comm, &graph->interface_subset_sf));
    1101:     PetscCall(PetscMalloc1(nli, &ilocal));
    1102:     PetscCall(PetscMalloc1(nli, &iremote));
    1103:     PetscCall(PetscMalloc2(mss, &queue_global_uniq, mss, &touched));
    1104:     for (PetscInt i = 0, nli = 0; i < graph->n_subsets; i++) {
    1105:       const PetscMPIInt rr                = (PetscMPIInt)subs_remote[i].rank;
    1106:       const PetscInt    start             = start_rsize[i];
    1107:       const PetscInt    subset_size       = graph->subset_size[i];
    1108:       const PetscInt    gsubset_size      = graph->gsubset_size[i];
    1109:       const PetscInt   *subset_idxs       = graph->subset_idxs[i];
    1110:       const PetscInt   *lsub_queue_global = queue_global + graph->cptr[i];

    1112:       k = subset_size;
    1113:       PetscCall(PetscArrayzero(touched, subset_size));
    1114:       PetscCall(PetscArraycpy(queue_global_uniq, lsub_queue_global, subset_size));
    1115:       PetscCall(PetscSortRemoveDupsInt(&k, queue_global_uniq));
    1116:       PetscCheck(k == gsubset_size, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Invalid local subset %" PetscInt_FMT " size %" PetscInt_FMT " != %" PetscInt_FMT, i, k, gsubset_size);

    1118:       PetscInt t = 0, j = 0;
    1119:       while (t < subset_size) {
    1120:         while (j < subset_size && touched[j]) j++;
    1121:         PetscCheck(j < subset_size, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Unexpected %" PetscInt_FMT " >= %" PetscInt_FMT, j, subset_size);
    1122:         const PetscInt ls = graph->nodes[subset_idxs[j]].local_sub;

    1124:         for (k = j; k < subset_size; k++) {
    1125:           if (graph->nodes[subset_idxs[k]].local_sub == ls) {
    1126:             PetscInt ig;

    1128:             PetscCall(PetscFindInt(lsub_queue_global[k], gsubset_size, queue_global_uniq, &ig));
    1129:             ilocal[nli]        = subset_idxs[k];
    1130:             iremote[nli].rank  = rr;
    1131:             iremote[nli].index = start + ig;
    1132:             touched[k]         = PETSC_TRUE;
    1133:             nli++;
    1134:             t++;
    1135:           }
    1136:         }
    1137:       }
    1138:     }
    1139:     PetscCheck(nli == graph->cptr[graph->ncc], PETSC_COMM_SELF, PETSC_ERR_PLIB, "Invalid ilocal size %" PetscInt_FMT " != %" PetscInt_FMT, nli, graph->cptr[graph->ncc]);
    1140:     PetscCall(PetscSFSetGraph(graph->interface_subset_sf, nri, nli, ilocal, PETSC_OWN_POINTER, iremote, PETSC_OWN_POINTER));
    1141:     PetscCall(PetscFree(start_rsize));
    1142:     PetscCall(PetscFree2(queue_global_uniq, touched));
    1143:   }
    1144:   PetscCall(PetscFree(queue_global));

    1146:   /* free workspace */
    1147:   graph->setupcalled = PETSC_TRUE;
    1148:   PetscFunctionReturn(PETSC_SUCCESS);
    1149: }

    1151: PetscErrorCode PCBDDCGraphResetCoords(PCBDDCGraph graph)
    1152: {
    1153:   PetscFunctionBegin;
    1154:   if (!graph) PetscFunctionReturn(PETSC_SUCCESS);
    1155:   PetscCall(PetscFree(graph->coords));
    1156:   graph->cdim  = 0;
    1157:   graph->cnloc = 0;
    1158:   graph->cloc  = PETSC_FALSE;
    1159:   PetscFunctionReturn(PETSC_SUCCESS);
    1160: }

    1162: PetscErrorCode PCBDDCGraphResetCSR(PCBDDCGraph graph)
    1163: {
    1164:   PetscFunctionBegin;
    1165:   if (!graph) PetscFunctionReturn(PETSC_SUCCESS);
    1166:   if (graph->freecsr) {
    1167:     PetscCall(PetscFree(graph->xadj));
    1168:     PetscCall(PetscFree(graph->adjncy));
    1169:   } else {
    1170:     graph->xadj   = NULL;
    1171:     graph->adjncy = NULL;
    1172:   }
    1173:   graph->freecsr   = PETSC_FALSE;
    1174:   graph->nvtxs_csr = 0;
    1175:   PetscFunctionReturn(PETSC_SUCCESS);
    1176: }

    1178: PetscErrorCode PCBDDCGraphReset(PCBDDCGraph graph)
    1179: {
    1180:   PetscFunctionBegin;
    1181:   if (!graph) PetscFunctionReturn(PETSC_SUCCESS);
    1182:   PetscCall(ISLocalToGlobalMappingDestroy(&graph->l2gmap));
    1183:   PetscCall(PetscFree(graph->subset_ncc));
    1184:   PetscCall(PetscFree(graph->subset_ref_node));
    1185:   for (PetscInt i = 0; i < graph->nvtxs; i++) {
    1186:     PetscCall(PetscFree(graph->nodes[i].neighbours_set));
    1187:     PetscCall(PetscFree(graph->nodes[i].local_groups));
    1188:   }
    1189:   PetscCall(PetscFree(graph->nodes));
    1190:   PetscCall(PetscFree2(graph->cptr, graph->queue));
    1191:   if (graph->subset_idxs) PetscCall(PetscFree(graph->subset_idxs[0]));
    1192:   PetscCall(PetscFree2(graph->subset_size, graph->subset_idxs));
    1193:   if (graph->multi_element) PetscCall(PetscFree(graph->gsubset_size));
    1194:   PetscCall(PetscFree(graph->interface_ref_rsize));
    1195:   PetscCall(PetscSFDestroy(&graph->interface_subset_sf));
    1196:   PetscCall(PetscSFDestroy(&graph->interface_ref_sf));
    1197:   PetscCall(ISDestroy(&graph->dirdofs));
    1198:   PetscCall(ISDestroy(&graph->dirdofsB));
    1199:   if (graph->n_local_subs) PetscCall(PetscFree(graph->local_subs));
    1200:   graph->multi_element       = PETSC_FALSE;
    1201:   graph->has_dirichlet       = PETSC_FALSE;
    1202:   graph->twodimset           = PETSC_FALSE;
    1203:   graph->twodim              = PETSC_FALSE;
    1204:   graph->nvtxs               = 0;
    1205:   graph->nvtxs_global        = 0;
    1206:   graph->n_subsets           = 0;
    1207:   graph->custom_minimal_size = 1;
    1208:   graph->n_local_subs        = 0;
    1209:   graph->maxcount            = PETSC_INT_MAX;
    1210:   graph->seq_graph           = PETSC_FALSE;
    1211:   graph->setupcalled         = PETSC_FALSE;
    1212:   PetscFunctionReturn(PETSC_SUCCESS);
    1213: }

    1215: PetscErrorCode PCBDDCGraphInit(PCBDDCGraph graph, ISLocalToGlobalMapping l2gmap, PetscInt N, PetscInt maxcount)
    1216: {
    1217:   PetscInt n;

    1219:   PetscFunctionBegin;
    1220:   PetscAssertPointer(graph, 1);
    1224:   /* raise an error if already allocated */
    1225:   PetscCheck(!graph->nvtxs_global, PetscObjectComm((PetscObject)l2gmap), PETSC_ERR_PLIB, "BDDCGraph already initialized");
    1226:   /* set number of vertices */
    1227:   PetscCall(PetscObjectReference((PetscObject)l2gmap));
    1228:   graph->l2gmap = l2gmap;
    1229:   PetscCall(ISLocalToGlobalMappingGetSize(l2gmap, &n));
    1230:   graph->nvtxs        = n;
    1231:   graph->nvtxs_global = N;
    1232:   /* allocate used space */
    1233:   PetscCall(PetscCalloc1(graph->nvtxs, &graph->nodes));
    1234:   /* use -1 as a default value for which_dof array */
    1235:   for (n = 0; n < graph->nvtxs; n++) graph->nodes[n].which_dof = -1;

    1237:   /* zeroes workspace for values of ncc */
    1238:   graph->subset_ncc      = NULL;
    1239:   graph->subset_ref_node = NULL;
    1240:   /* maxcount for cc */
    1241:   graph->maxcount = maxcount;
    1242:   PetscFunctionReturn(PETSC_SUCCESS);
    1243: }

    1245: PetscErrorCode PCBDDCGraphDestroy(PCBDDCGraph *graph)
    1246: {
    1247:   PetscFunctionBegin;
    1248:   PetscCall(PCBDDCGraphResetCSR(*graph));
    1249:   PetscCall(PCBDDCGraphResetCoords(*graph));
    1250:   PetscCall(PCBDDCGraphReset(*graph));
    1251:   PetscCall(PetscFree(*graph));
    1252:   PetscFunctionReturn(PETSC_SUCCESS);
    1253: }

    1255: PetscErrorCode PCBDDCGraphCreate(PCBDDCGraph *graph)
    1256: {
    1257:   PCBDDCGraph new_graph;

    1259:   PetscFunctionBegin;
    1260:   PetscCall(PetscNew(&new_graph));
    1261:   new_graph->custom_minimal_size = 1;
    1262:   *graph                         = new_graph;
    1263:   PetscFunctionReturn(PETSC_SUCCESS);
    1264: }