Date: 2022-03-04T17:38:28+00:00

Actual source code: plexorient.c

      1: #include <petsc/private/dmpleximpl.h>
      2: #include <petscsf.h>

      4: /*@
      5:   DMPlexOrientPoint - Act with the given orientation on the cone points of this mesh point, and update its use in the mesh.

      7:   Not Collective

      9:   Input Parameters:
     10: + dm - The DM
     11: . p  - The mesh point
     12: - o  - The orientation

     14:   Level: intermediate

     16: .seealso: DMPlexOrient(), DMPlexGetCone(), DMPlexGetConeOrientation(), DMPlexInterpolate(), DMPlexGetChart()
     17: @*/
     18: PetscErrorCode DMPlexOrientPoint(DM dm, PetscInt p, PetscInt o)
     19: {
     20:   DMPolytopeType  ct;
     21:   const PetscInt *arr, *cone, *ornt, *support;
     22:   PetscInt       *newcone, *newornt;
     23:   PetscInt        coneSize, c, supportSize, s;
     24:   PetscErrorCode  ierr;

     28:   DMPlexGetCellType(dm, p, &ct);
     29:   arr  = DMPolytopeTypeGetArrangment(ct, o);
     30:   DMPlexGetConeSize(dm, p, &coneSize);
     31:   DMPlexGetCone(dm, p, &cone);
     32:   DMPlexGetConeOrientation(dm, p, &ornt);
     33:   DMGetWorkArray(dm, coneSize, MPIU_INT, &newcone);
     34:   DMGetWorkArray(dm, coneSize, MPIU_INT, &newornt);
     35:   for (c = 0; c < coneSize; ++c) {
     36:     DMPolytopeType ft;
     37:     PetscInt       nO;

     39:     DMPlexGetCellType(dm, cone[c], &ft);
     40:     nO   = DMPolytopeTypeGetNumArrangments(ft)/2;
     41:     newcone[c] = cone[arr[c*2+0]];
     42:     newornt[c] = DMPolytopeTypeComposeOrientation(ft, arr[c*2+1], ornt[arr[c*2+0]]);
     43:     if (newornt[c] && (newornt[c] >= nO || newornt[c] < -nO)) SETERRQ5(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Invalid orientation %D not in [%D,%D) for %s %D", newornt[c], -nO, nO, DMPolytopeTypes[ft], cone[c]);
     44:   }
     45:   DMPlexSetCone(dm, p, newcone);
     46:   DMPlexSetConeOrientation(dm, p, newornt);
     47:   DMRestoreWorkArray(dm, coneSize, MPIU_INT, &newcone);
     48:   DMRestoreWorkArray(dm, coneSize, MPIU_INT, &newornt);
     49:   /* Update orientation of this point in the support points */
     50:   DMPlexGetSupportSize(dm, p, &supportSize);
     51:   DMPlexGetSupport(dm, p, &support);
     52:   for (s = 0; s < supportSize; ++s) {
     53:     DMPlexGetConeSize(dm, support[s], &coneSize);
     54:     DMPlexGetCone(dm, support[s], &cone);
     55:     DMPlexGetConeOrientation(dm, support[s], &ornt);
     56:     for (c = 0; c < coneSize; ++c) {
     57:       PetscInt po;

     59:       if (cone[c] != p) continue;
     60:       /* ornt[c] * 0 = target = po * o so that po = ornt[c] * o^{-1} */
     61:       po   = DMPolytopeTypeComposeOrientationInv(ct, ornt[c], o);
     62:       DMPlexInsertConeOrientation(dm, support[s], c, po);
     63:     }
     64:   }
     65:   return(0);
     66: }

     68: /*
     69:   - Checks face match
     70:     - Flips non-matching
     71:   - Inserts faces of support cells in FIFO
     72: */
     73: static PetscErrorCode DMPlexCheckFace_Internal(DM dm, PetscInt *faceFIFO, PetscInt *fTop, PetscInt *fBottom, PetscInt cStart, PetscInt fStart, PetscInt fEnd, PetscBT seenCells, PetscBT flippedCells, PetscBT seenFaces)
     74: {
     75:   const PetscInt *support, *coneA, *coneB, *coneOA, *coneOB;
     76:   PetscInt        supportSize, coneSizeA, coneSizeB, posA = -1, posB = -1;
     77:   PetscInt        face, dim, seenA, flippedA, seenB, flippedB, mismatch, c;
     78:   PetscErrorCode  ierr;

     81:   face = faceFIFO[(*fTop)++];
     82:   DMGetDimension(dm, &dim);
     83:   DMPlexGetSupportSize(dm, face, &supportSize);
     84:   DMPlexGetSupport(dm, face, &support);
     85:   if (supportSize < 2) return(0);
     86:   if (supportSize != 2) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Faces should separate only two cells, not %d", supportSize);
     87:   seenA    = PetscBTLookup(seenCells,    support[0]-cStart);
     88:   flippedA = PetscBTLookup(flippedCells, support[0]-cStart) ? 1 : 0;
     89:   seenB    = PetscBTLookup(seenCells,    support[1]-cStart);
     90:   flippedB = PetscBTLookup(flippedCells, support[1]-cStart) ? 1 : 0;

     92:   DMPlexGetConeSize(dm, support[0], &coneSizeA);
     93:   DMPlexGetConeSize(dm, support[1], &coneSizeB);
     94:   DMPlexGetCone(dm, support[0], &coneA);
     95:   DMPlexGetCone(dm, support[1], &coneB);
     96:   DMPlexGetConeOrientation(dm, support[0], &coneOA);
     97:   DMPlexGetConeOrientation(dm, support[1], &coneOB);
     98:   for (c = 0; c < coneSizeA; ++c) {
     99:     if (!PetscBTLookup(seenFaces, coneA[c]-fStart)) {
    100:       faceFIFO[(*fBottom)++] = coneA[c];
    101:       PetscBTSet(seenFaces, coneA[c]-fStart);
    102:     }
    103:     if (coneA[c] == face) posA = c;
    104:     if (*fBottom > fEnd-fStart) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Face %d was pushed exceeding capacity %d > %d", coneA[c], *fBottom, fEnd-fStart);
    105:   }
    106:   if (posA < 0) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Face %d could not be located in cell %d", face, support[0]);
    107:   for (c = 0; c < coneSizeB; ++c) {
    108:     if (!PetscBTLookup(seenFaces, coneB[c]-fStart)) {
    109:       faceFIFO[(*fBottom)++] = coneB[c];
    110:       PetscBTSet(seenFaces, coneB[c]-fStart);
    111:     }
    112:     if (coneB[c] == face) posB = c;
    113:     if (*fBottom > fEnd-fStart) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Face %d was pushed exceeding capacity %d > %d", coneA[c], *fBottom, fEnd-fStart);
    114:   }
    115:   if (posB < 0) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Face %d could not be located in cell %d", face, support[1]);

    117:   if (dim == 1) {
    118:     mismatch = posA == posB;
    119:   } else {
    120:     mismatch = coneOA[posA] == coneOB[posB];
    121:   }

    123:   if (mismatch ^ (flippedA ^ flippedB)) {
    124:     if (seenA && seenB) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Previously seen cells %d and %d do not match: Fault mesh is non-orientable", support[0], support[1]);
    125:     if (!seenA && !flippedA) {
    126:       PetscBTSet(flippedCells, support[0]-cStart);
    127:     } else if (!seenB && !flippedB) {
    128:       PetscBTSet(flippedCells, support[1]-cStart);
    129:     } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Inconsistent mesh orientation: Fault mesh is non-orientable");
    130:   } else if (mismatch && flippedA && flippedB) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Attempt to flip already flipped cell: Fault mesh is non-orientable");
    131:   PetscBTSet(seenCells, support[0]-cStart);
    132:   PetscBTSet(seenCells, support[1]-cStart);
    133:   return(0);
    134: }

    136: /*@
    137:   DMPlexOrient - Give a consistent orientation to the input mesh

    139:   Input Parameters:
    140: . dm - The DM

    142:   Note: The orientation data for the DM are change in-place.
    143: $ This routine will fail for non-orientable surfaces, such as the Moebius strip.

    145:   Level: advanced

    147: .seealso: DMCreate(), DMPLEX
    148: @*/
    149: PetscErrorCode DMPlexOrient(DM dm)
    150: {
    151:   MPI_Comm           comm;
    152:   PetscSF            sf;
    153:   const PetscInt    *lpoints;
    154:   const PetscSFNode *rpoints;
    155:   PetscSFNode       *rorntComp = NULL, *lorntComp = NULL;
    156:   PetscInt          *numNeighbors, **neighbors;
    157:   PetscSFNode       *nrankComp;
    158:   PetscBool         *match, *flipped;
    159:   PetscBT            seenCells, flippedCells, seenFaces;
    160:   PetscInt          *faceFIFO, fTop, fBottom, *cellComp, *faceComp;
    161:   PetscInt           numLeaves, numRoots, dim, h, cStart, cEnd, c, cell, fStart, fEnd, face, off, totNeighbors = 0;
    162:   PetscMPIInt        rank, size, numComponents, comp = 0;
    163:   PetscBool          flg, flg2;
    164:   PetscViewer        viewer = NULL, selfviewer = NULL;
    165:   PetscErrorCode     ierr;

    168:   PetscObjectGetComm((PetscObject) dm, &comm);
    169:   MPI_Comm_rank(comm, &rank);
    170:   MPI_Comm_size(comm, &size);
    171:   PetscOptionsHasName(((PetscObject) dm)->options,((PetscObject) dm)->prefix, "-orientation_view", &flg);
    172:   PetscOptionsHasName(((PetscObject) dm)->options,((PetscObject) dm)->prefix, "-orientation_view_synchronized", &flg2);
    173:   DMGetPointSF(dm, &sf);
    174:   PetscSFGetGraph(sf, &numRoots, &numLeaves, &lpoints, &rpoints);
    175:   /* Truth Table
    176:      mismatch    flips   do action   mismatch   flipA ^ flipB   action
    177:          F       0 flips     no         F             F           F
    178:          F       1 flip      yes        F             T           T
    179:          F       2 flips     no         T             F           T
    180:          T       0 flips     yes        T             T           F
    181:          T       1 flip      no
    182:          T       2 flips     yes
    183:   */
    184:   DMGetDimension(dm, &dim);
    185:   DMPlexGetVTKCellHeight(dm, &h);
    186:   DMPlexGetHeightStratum(dm, h,   &cStart, &cEnd);
    187:   DMPlexGetHeightStratum(dm, h+1, &fStart, &fEnd);
    188:   PetscBTCreate(cEnd - cStart, &seenCells);
    189:   PetscBTMemzero(cEnd - cStart, seenCells);
    190:   PetscBTCreate(cEnd - cStart, &flippedCells);
    191:   PetscBTMemzero(cEnd - cStart, flippedCells);
    192:   PetscBTCreate(fEnd - fStart, &seenFaces);
    193:   PetscBTMemzero(fEnd - fStart, seenFaces);
    194:   PetscCalloc3(fEnd - fStart, &faceFIFO, cEnd-cStart, &cellComp, fEnd-fStart, &faceComp);
    195:   /*
    196:    OLD STYLE
    197:    - Add an integer array over cells and faces (component) for connected component number
    198:    Foreach component
    199:      - Mark the initial cell as seen
    200:      - Process component as usual
    201:      - Set component for all seenCells
    202:      - Wipe seenCells and seenFaces (flippedCells can stay)
    203:    - Generate parallel adjacency for component using SF and seenFaces
    204:    - Collect numComponents adj data from each proc to 0
    205:    - Build same serial graph
    206:    - Use same solver
    207:    - Use Scatterv to to send back flipped flags for each component
    208:    - Negate flippedCells by component

    210:    NEW STYLE
    211:    - Create the adj on each process
    212:    - Bootstrap to complete graph on proc 0
    213:   */
    214:   /* Loop over components */
    215:   for (cell = cStart; cell < cEnd; ++cell) cellComp[cell-cStart] = -1;
    216:   do {
    217:     /* Look for first unmarked cell */
    218:     for (cell = cStart; cell < cEnd; ++cell) if (cellComp[cell-cStart] < 0) break;
    219:     if (cell >= cEnd) break;
    220:     /* Initialize FIFO with first cell in component */
    221:     {
    222:       const PetscInt *cone;
    223:       PetscInt        coneSize;

    225:       fTop = fBottom = 0;
    226:       DMPlexGetConeSize(dm, cell, &coneSize);
    227:       DMPlexGetCone(dm, cell, &cone);
    228:       for (c = 0; c < coneSize; ++c) {
    229:         faceFIFO[fBottom++] = cone[c];
    230:         PetscBTSet(seenFaces, cone[c]-fStart);
    231:       }
    232:       PetscBTSet(seenCells, cell-cStart);
    233:     }
    234:     /* Consider each face in FIFO */
    235:     while (fTop < fBottom) {
    236:       DMPlexCheckFace_Internal(dm, faceFIFO, &fTop, &fBottom, cStart, fStart, fEnd, seenCells, flippedCells, seenFaces);
    237:     }
    238:     /* Set component for cells and faces */
    239:     for (cell = 0; cell < cEnd-cStart; ++cell) {
    240:       if (PetscBTLookup(seenCells, cell)) cellComp[cell] = comp;
    241:     }
    242:     for (face = 0; face < fEnd-fStart; ++face) {
    243:       if (PetscBTLookup(seenFaces, face)) faceComp[face] = comp;
    244:     }
    245:     /* Wipe seenCells and seenFaces for next component */
    246:     PetscBTMemzero(fEnd - fStart, seenFaces);
    247:     PetscBTMemzero(cEnd - cStart, seenCells);
    248:     ++comp;
    249:   } while (1);
    250:   numComponents = comp;
    251:   if (flg) {
    252:     PetscViewer v;

    254:     PetscViewerASCIIGetStdout(comm, &v);
    255:     PetscViewerASCIIPushSynchronized(v);
    256:     PetscViewerASCIISynchronizedPrintf(v, "[%d]BT for serial flipped cells:\n", rank);
    257:     PetscBTView(cEnd-cStart, flippedCells, v);
    258:     PetscViewerFlush(v);
    259:     PetscViewerASCIIPopSynchronized(v);
    260:   }
    261:   /* Now all subdomains are oriented, but we need a consistent parallel orientation */
    262:   if (numLeaves >= 0) {
    263:     /* Store orientations of boundary faces*/
    264:     PetscCalloc2(numRoots,&rorntComp,numRoots,&lorntComp);
    265:     for (face = fStart; face < fEnd; ++face) {
    266:       const PetscInt *cone, *support, *ornt;
    267:       PetscInt        coneSize, supportSize;

    269:       DMPlexGetSupportSize(dm, face, &supportSize);
    270:       if (supportSize != 1) continue;
    271:       DMPlexGetSupport(dm, face, &support);

    273:       DMPlexGetCone(dm, support[0], &cone);
    274:       DMPlexGetConeSize(dm, support[0], &coneSize);
    275:       DMPlexGetConeOrientation(dm, support[0], &ornt);
    276:       for (c = 0; c < coneSize; ++c) if (cone[c] == face) break;
    277:       if (dim == 1) {
    278:         /* Use cone position instead, shifted to -1 or 1 */
    279:         if (PetscBTLookup(flippedCells, support[0]-cStart)) rorntComp[face].rank = 1-c*2;
    280:         else                                                rorntComp[face].rank = c*2-1;
    281:       } else {
    282:         if (PetscBTLookup(flippedCells, support[0]-cStart)) rorntComp[face].rank = ornt[c] < 0 ? -1 :  1;
    283:         else                                                rorntComp[face].rank = ornt[c] < 0 ?  1 : -1;
    284:       }
    285:       rorntComp[face].index = faceComp[face-fStart];
    286:     }
    287:     /* Communicate boundary edge orientations */
    288:     PetscSFBcastBegin(sf, MPIU_2INT, rorntComp, lorntComp,MPI_REPLACE);
    289:     PetscSFBcastEnd(sf, MPIU_2INT, rorntComp, lorntComp,MPI_REPLACE);
    290:   }
    291:   /* Get process adjacency */
    292:   PetscMalloc2(numComponents, &numNeighbors, numComponents, &neighbors);
    293:   viewer = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)dm));
    294:   if (flg2) {PetscViewerASCIIPushSynchronized(viewer);}
    295:   PetscViewerGetSubViewer(viewer,PETSC_COMM_SELF,&selfviewer);
    296:   for (comp = 0; comp < numComponents; ++comp) {
    297:     PetscInt  l, n;

    299:     numNeighbors[comp] = 0;
    300:     PetscMalloc1(PetscMax(numLeaves, 0), &neighbors[comp]);
    301:     /* I know this is p^2 time in general, but for bounded degree its alright */
    302:     for (l = 0; l < numLeaves; ++l) {
    303:       const PetscInt face = lpoints[l];

    305:       /* Find a representative face (edge) separating pairs of procs */
    306:       if ((face >= fStart) && (face < fEnd) && (faceComp[face-fStart] == comp)) {
    307:         const PetscInt rrank = rpoints[l].rank;
    308:         const PetscInt rcomp = lorntComp[face].index;

    310:         for (n = 0; n < numNeighbors[comp]; ++n) if ((rrank == rpoints[neighbors[comp][n]].rank) && (rcomp == lorntComp[lpoints[neighbors[comp][n]]].index)) break;
    311:         if (n >= numNeighbors[comp]) {
    312:           PetscInt supportSize;

    314:           DMPlexGetSupportSize(dm, face, &supportSize);
    315:           if (supportSize != 1) SETERRQ1(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Boundary faces should see one cell, not %d", supportSize);
    316:           if (flg) {PetscViewerASCIIPrintf(selfviewer, "[%d]: component %d, Found representative leaf %d (face %d) connecting to face %d on (%d, %d) with orientation %d\n", rank, comp, l, face, rpoints[l].index, rrank, rcomp, lorntComp[face].rank);}
    317:           neighbors[comp][numNeighbors[comp]++] = l;
    318:         }
    319:       }
    320:     }
    321:     totNeighbors += numNeighbors[comp];
    322:   }
    323:   PetscViewerRestoreSubViewer(viewer,PETSC_COMM_SELF,&selfviewer);
    324:   PetscViewerFlush(viewer);
    325:   if (flg2) {PetscViewerASCIIPopSynchronized(viewer);}
    326:   PetscMalloc2(totNeighbors, &nrankComp, totNeighbors, &match);
    327:   for (comp = 0, off = 0; comp < numComponents; ++comp) {
    328:     PetscInt n;

    330:     for (n = 0; n < numNeighbors[comp]; ++n, ++off) {
    331:       const PetscInt face = lpoints[neighbors[comp][n]];
    332:       const PetscInt o    = rorntComp[face].rank*lorntComp[face].rank;

    334:       if      (o < 0) match[off] = PETSC_TRUE;
    335:       else if (o > 0) match[off] = PETSC_FALSE;
    336:       else SETERRQ5(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Invalid face %d (%d, %d) neighbor: %d comp: %d", face, rorntComp[face], lorntComp[face], neighbors[comp][n], comp);
    337:       nrankComp[off].rank  = rpoints[neighbors[comp][n]].rank;
    338:       nrankComp[off].index = lorntComp[lpoints[neighbors[comp][n]]].index;
    339:     }
    340:     PetscFree(neighbors[comp]);
    341:   }
    342:   /* Collect the graph on 0 */
    343:   if (numLeaves >= 0) {
    344:     Mat          G;
    345:     PetscBT      seenProcs, flippedProcs;
    346:     PetscInt    *procFIFO, pTop, pBottom;
    347:     PetscInt    *N   = NULL, *Noff;
    348:     PetscSFNode *adj = NULL;
    349:     PetscBool   *val = NULL;
    350:     PetscMPIInt *recvcounts = NULL, *displs = NULL, *Nc, p, o;
    351:     PetscMPIInt  size = 0;

    353:     PetscCalloc1(numComponents, &flipped);
    354:     if (rank == 0) {MPI_Comm_size(comm, &size);}
    355:     PetscCalloc4(size, &recvcounts, size+1, &displs, size, &Nc, size+1, &Noff);
    356:     MPI_Gather(&numComponents, 1, MPI_INT, Nc, 1, MPI_INT, 0, comm);
    357:     for (p = 0; p < size; ++p) {
    358:       displs[p+1] = displs[p] + Nc[p];
    359:     }
    360:     if (rank == 0) {PetscMalloc1(displs[size],&N);}
    361:     MPI_Gatherv(numNeighbors, numComponents, MPIU_INT, N, Nc, displs, MPIU_INT, 0, comm);
    362:     for (p = 0, o = 0; p < size; ++p) {
    363:       recvcounts[p] = 0;
    364:       for (c = 0; c < Nc[p]; ++c, ++o) recvcounts[p] += N[o];
    365:       displs[p+1] = displs[p] + recvcounts[p];
    366:     }
    367:     if (rank == 0) {PetscMalloc2(displs[size], &adj, displs[size], &val);}
    368:     MPI_Gatherv(nrankComp, totNeighbors, MPIU_2INT, adj, recvcounts, displs, MPIU_2INT, 0, comm);
    369:     MPI_Gatherv(match, totNeighbors, MPIU_BOOL, val, recvcounts, displs, MPIU_BOOL, 0, comm);
    370:     PetscFree2(numNeighbors, neighbors);
    371:     if (rank == 0) {
    372:       for (p = 1; p <= size; ++p) {Noff[p] = Noff[p-1] + Nc[p-1];}
    373:       if (flg) {
    374:         PetscInt n;

    376:         for (p = 0, off = 0; p < size; ++p) {
    377:           for (c = 0; c < Nc[p]; ++c) {
    378:             PetscPrintf(PETSC_COMM_SELF, "Proc %d Comp %d:\n", p, c);
    379:             for (n = 0; n < N[Noff[p]+c]; ++n, ++off) {
    380:               PetscPrintf(PETSC_COMM_SELF, "  edge (%d, %d) (%d):\n", adj[off].rank, adj[off].index, val[off]);
    381:             }
    382:           }
    383:         }
    384:       }
    385:       /* Symmetrize the graph */
    386:       MatCreate(PETSC_COMM_SELF, &G);
    387:       MatSetSizes(G, Noff[size], Noff[size], Noff[size], Noff[size]);
    388:       MatSetUp(G);
    389:       for (p = 0, off = 0; p < size; ++p) {
    390:         for (c = 0; c < Nc[p]; ++c) {
    391:           const PetscInt r = Noff[p]+c;
    392:           PetscInt       n;

    394:           for (n = 0; n < N[r]; ++n, ++off) {
    395:             const PetscInt    q = Noff[adj[off].rank] + adj[off].index;
    396:             const PetscScalar o = val[off] ? 1.0 : 0.0;

    398:             MatSetValues(G, 1, &r, 1, &q, &o, INSERT_VALUES);
    399:             MatSetValues(G, 1, &q, 1, &r, &o, INSERT_VALUES);
    400:           }
    401:         }
    402:       }
    403:       MatAssemblyBegin(G, MAT_FINAL_ASSEMBLY);
    404:       MatAssemblyEnd(G, MAT_FINAL_ASSEMBLY);

    406:       PetscBTCreate(Noff[size], &seenProcs);
    407:       PetscBTMemzero(Noff[size], seenProcs);
    408:       PetscBTCreate(Noff[size], &flippedProcs);
    409:       PetscBTMemzero(Noff[size], flippedProcs);
    410:       PetscMalloc1(Noff[size], &procFIFO);
    411:       pTop = pBottom = 0;
    412:       for (p = 0; p < Noff[size]; ++p) {
    413:         if (PetscBTLookup(seenProcs, p)) continue;
    414:         /* Initialize FIFO with next proc */
    415:         procFIFO[pBottom++] = p;
    416:         PetscBTSet(seenProcs, p);
    417:         /* Consider each proc in FIFO */
    418:         while (pTop < pBottom) {
    419:           const PetscScalar *ornt;
    420:           const PetscInt    *neighbors;
    421:           PetscInt           proc, nproc, seen, flippedA, flippedB, mismatch, numNeighbors, n;

    423:           proc     = procFIFO[pTop++];
    424:           flippedA = PetscBTLookup(flippedProcs, proc) ? 1 : 0;
    425:           MatGetRow(G, proc, &numNeighbors, &neighbors, &ornt);
    426:           /* Loop over neighboring procs */
    427:           for (n = 0; n < numNeighbors; ++n) {
    428:             nproc    = neighbors[n];
    429:             mismatch = PetscRealPart(ornt[n]) > 0.5 ? 0 : 1;
    430:             seen     = PetscBTLookup(seenProcs, nproc);
    431:             flippedB = PetscBTLookup(flippedProcs, nproc) ? 1 : 0;

    433:             if (mismatch ^ (flippedA ^ flippedB)) {
    434:               if (seen) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Previously seen procs %d and %d do not match: Fault mesh is non-orientable", proc, nproc);
    435:               if (!flippedB) {
    436:                 PetscBTSet(flippedProcs, nproc);
    437:               } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Inconsistent mesh orientation: Fault mesh is non-orientable");
    438:             } else if (mismatch && flippedA && flippedB) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Attempt to flip already flipped cell: Fault mesh is non-orientable");
    439:             if (!seen) {
    440:               procFIFO[pBottom++] = nproc;
    441:               PetscBTSet(seenProcs, nproc);
    442:             }
    443:           }
    444:         }
    445:       }
    446:       PetscFree(procFIFO);
    447:       MatDestroy(&G);
    448:       PetscFree2(adj, val);
    449:       PetscBTDestroy(&seenProcs);
    450:     }
    451:     /* Scatter flip flags */
    452:     {
    453:       PetscBool *flips = NULL;

    455:       if (rank == 0) {
    456:         PetscMalloc1(Noff[size], &flips);
    457:         for (p = 0; p < Noff[size]; ++p) {
    458:           flips[p] = PetscBTLookup(flippedProcs, p) ? PETSC_TRUE : PETSC_FALSE;
    459:           if (flg && flips[p]) {PetscPrintf(comm, "Flipping Proc+Comp %d:\n", p);}
    460:         }
    461:         for (p = 0; p < size; ++p) {
    462:           displs[p+1] = displs[p] + Nc[p];
    463:         }
    464:       }
    465:       MPI_Scatterv(flips, Nc, displs, MPIU_BOOL, flipped, numComponents, MPIU_BOOL, 0, comm);
    466:       PetscFree(flips);
    467:     }
    468:     if (rank == 0) {PetscBTDestroy(&flippedProcs);}
    469:     PetscFree(N);
    470:     PetscFree4(recvcounts, displs, Nc, Noff);
    471:     PetscFree2(nrankComp, match);

    473:     /* Decide whether to flip cells in each component */
    474:     for (c = 0; c < cEnd-cStart; ++c) {if (flipped[cellComp[c]]) {PetscBTNegate(flippedCells, c);}}
    475:     PetscFree(flipped);
    476:   }
    477:   if (flg) {
    478:     PetscViewer v;

    480:     PetscViewerASCIIGetStdout(comm, &v);
    481:     PetscViewerASCIIPushSynchronized(v);
    482:     PetscViewerASCIISynchronizedPrintf(v, "[%d]BT for parallel flipped cells:\n", rank);
    483:     PetscBTView(cEnd-cStart, flippedCells, v);
    484:     PetscViewerFlush(v);
    485:     PetscViewerASCIIPopSynchronized(v);
    486:   }
    487:   /* Reverse flipped cells in the mesh */
    488:   for (c = cStart; c < cEnd; ++c) {
    489:     if (PetscBTLookup(flippedCells, c-cStart)) {
    490:       DMPlexOrientPoint(dm, c, -1);
    491:     }
    492:   }
    493:   PetscBTDestroy(&seenCells);
    494:   PetscBTDestroy(&flippedCells);
    495:   PetscBTDestroy(&seenFaces);
    496:   PetscFree2(numNeighbors, neighbors);
    497:   PetscFree2(rorntComp, lorntComp);
    498:   PetscFree3(faceFIFO, cellComp, faceComp);
    499:   return(0);
    500: }