xref: /petsc/src/dm/impls/plex/plexsubmesh.c (revision 8cc058d9cd56c1ccb3be12a47760ddfc446aaffc)
1 #include <petsc-private/dmpleximpl.h>   /*I      "petscdmplex.h"   I*/
2 
3 extern PetscErrorCode DMPlexGetNumFaceVertices_Internal(DM, PetscInt, PetscInt, PetscInt *);
4 
5 #undef __FUNCT__
6 #define __FUNCT__ "DMPlexMarkBoundaryFaces"
7 /*@
8   DMPlexMarkBoundaryFaces - Mark all faces on the boundary
9 
10   Not Collective
11 
12   Input Parameter:
13 . dm - The original DM
14 
15   Output Parameter:
16 . label - The DMLabel marking boundary faces with value 1
17 
18   Level: developer
19 
20 .seealso: DMLabelCreate(), DMPlexCreateLabel()
21 @*/
22 PetscErrorCode DMPlexMarkBoundaryFaces(DM dm, DMLabel label)
23 {
24   PetscInt       fStart, fEnd, f;
25   PetscErrorCode ierr;
26 
27   PetscFunctionBegin;
28   PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
29   ierr = DMPlexGetHeightStratum(dm, 1, &fStart, &fEnd);CHKERRQ(ierr);
30   for (f = fStart; f < fEnd; ++f) {
31     PetscInt supportSize;
32 
33     ierr = DMPlexGetSupportSize(dm, f, &supportSize);CHKERRQ(ierr);
34     if (supportSize == 1) {
35       ierr = DMLabelSetValue(label, f, 1);CHKERRQ(ierr);
36     }
37   }
38   PetscFunctionReturn(0);
39 }
40 
41 #undef __FUNCT__
42 #define __FUNCT__ "DMPlexShiftPoint_Internal"
43 PETSC_STATIC_INLINE PetscInt DMPlexShiftPoint_Internal(PetscInt p, PetscInt depth, PetscInt depthEnd[], PetscInt depthShift[])
44 {
45   if (depth < 0) return p;
46   /* Cells    */ if (p < depthEnd[depth])   return p;
47   /* Vertices */ if (p < depthEnd[0])       return p + depthShift[depth];
48   /* Faces    */ if (p < depthEnd[depth-1]) return p + depthShift[depth] + depthShift[0];
49   /* Edges    */                            return p + depthShift[depth] + depthShift[0] + depthShift[depth-1];
50 }
51 
52 #undef __FUNCT__
53 #define __FUNCT__ "DMPlexShiftSizes_Internal"
54 static PetscErrorCode DMPlexShiftSizes_Internal(DM dm, PetscInt depthShift[], DM dmNew)
55 {
56   PetscInt      *depthEnd;
57   PetscInt       depth = 0, d, pStart, pEnd, p;
58   PetscErrorCode ierr;
59 
60   PetscFunctionBegin;
61   ierr = DMPlexGetDepth(dm, &depth);CHKERRQ(ierr);
62   if (depth < 0) PetscFunctionReturn(0);
63   ierr = PetscMalloc((depth+1) * sizeof(PetscInt), &depthEnd);CHKERRQ(ierr);
64   /* Step 1: Expand chart */
65   ierr = DMPlexGetChart(dm, &pStart, &pEnd);CHKERRQ(ierr);
66   for (d = 0; d <= depth; ++d) {
67     pEnd += depthShift[d];
68     ierr  = DMPlexGetDepthStratum(dm, d, NULL, &depthEnd[d]);CHKERRQ(ierr);
69   }
70   ierr = DMPlexSetChart(dmNew, pStart, pEnd);CHKERRQ(ierr);
71   /* Step 2: Set cone and support sizes */
72   for (d = 0; d <= depth; ++d) {
73     ierr = DMPlexGetDepthStratum(dm, d, &pStart, &pEnd);CHKERRQ(ierr);
74     for (p = pStart; p < pEnd; ++p) {
75       PetscInt newp = DMPlexShiftPoint_Internal(p, depth, depthEnd, depthShift);
76       PetscInt size;
77 
78       ierr = DMPlexGetConeSize(dm, p, &size);CHKERRQ(ierr);
79       ierr = DMPlexSetConeSize(dmNew, newp, size);CHKERRQ(ierr);
80       ierr = DMPlexGetSupportSize(dm, p, &size);CHKERRQ(ierr);
81       ierr = DMPlexSetSupportSize(dmNew, newp, size);CHKERRQ(ierr);
82     }
83   }
84   ierr = PetscFree(depthEnd);CHKERRQ(ierr);
85   PetscFunctionReturn(0);
86 }
87 
88 #undef __FUNCT__
89 #define __FUNCT__ "DMPlexShiftPoints_Internal"
90 static PetscErrorCode DMPlexShiftPoints_Internal(DM dm, PetscInt depthShift[], DM dmNew)
91 {
92   PetscInt      *depthEnd, *newpoints;
93   PetscInt       depth = 0, d, maxConeSize, maxSupportSize, pStart, pEnd, p;
94   PetscErrorCode ierr;
95 
96   PetscFunctionBegin;
97   ierr = DMPlexGetDepth(dm, &depth);CHKERRQ(ierr);
98   if (depth < 0) PetscFunctionReturn(0);
99   ierr = DMPlexGetMaxSizes(dm, &maxConeSize, &maxSupportSize);CHKERRQ(ierr);
100   ierr = PetscMalloc2(depth+1,PetscInt,&depthEnd,PetscMax(maxConeSize, maxSupportSize),PetscInt,&newpoints);CHKERRQ(ierr);
101   for (d = 0; d <= depth; ++d) {
102     ierr = DMPlexGetDepthStratum(dm, d, NULL, &depthEnd[d]);CHKERRQ(ierr);
103   }
104   /* Step 5: Set cones and supports */
105   ierr = DMPlexGetChart(dm, &pStart, &pEnd);CHKERRQ(ierr);
106   for (p = pStart; p < pEnd; ++p) {
107     const PetscInt *points = NULL, *orientations = NULL;
108     PetscInt        size, i, newp = DMPlexShiftPoint_Internal(p, depth, depthEnd, depthShift);
109 
110     ierr = DMPlexGetConeSize(dm, p, &size);CHKERRQ(ierr);
111     ierr = DMPlexGetCone(dm, p, &points);CHKERRQ(ierr);
112     ierr = DMPlexGetConeOrientation(dm, p, &orientations);CHKERRQ(ierr);
113     for (i = 0; i < size; ++i) {
114       newpoints[i] = DMPlexShiftPoint_Internal(points[i], depth, depthEnd, depthShift);
115     }
116     ierr = DMPlexSetCone(dmNew, newp, newpoints);CHKERRQ(ierr);
117     ierr = DMPlexSetConeOrientation(dmNew, newp, orientations);CHKERRQ(ierr);
118     ierr = DMPlexGetSupportSize(dm, p, &size);CHKERRQ(ierr);
119     ierr = DMPlexGetSupport(dm, p, &points);CHKERRQ(ierr);
120     for (i = 0; i < size; ++i) {
121       newpoints[i] = DMPlexShiftPoint_Internal(points[i], depth, depthEnd, depthShift);
122     }
123     ierr = DMPlexSetSupport(dmNew, newp, newpoints);CHKERRQ(ierr);
124   }
125   ierr = PetscFree2(depthEnd,newpoints);CHKERRQ(ierr);
126   PetscFunctionReturn(0);
127 }
128 
129 #undef __FUNCT__
130 #define __FUNCT__ "DMPlexShiftCoordinates_Internal"
131 static PetscErrorCode DMPlexShiftCoordinates_Internal(DM dm, PetscInt depthShift[], DM dmNew)
132 {
133   PetscSection   coordSection, newCoordSection;
134   Vec            coordinates, newCoordinates;
135   PetscScalar   *coords, *newCoords;
136   PetscInt      *depthEnd, coordSize;
137   PetscInt       dim, depth = 0, d, vStart, vEnd, vStartNew, vEndNew, v;
138   PetscErrorCode ierr;
139 
140   PetscFunctionBegin;
141   ierr = DMPlexGetDimension(dm, &dim);CHKERRQ(ierr);
142   ierr = DMPlexGetDepth(dm, &depth);CHKERRQ(ierr);
143   ierr = PetscMalloc((depth+1) * sizeof(PetscInt), &depthEnd);CHKERRQ(ierr);
144   for (d = 0; d <= depth; ++d) {
145     ierr = DMPlexGetDepthStratum(dm, d, NULL, &depthEnd[d]);CHKERRQ(ierr);
146   }
147   /* Step 8: Convert coordinates */
148   ierr = DMPlexGetDepthStratum(dm, 0, &vStart, &vEnd);CHKERRQ(ierr);
149   ierr = DMPlexGetDepthStratum(dmNew, 0, &vStartNew, &vEndNew);CHKERRQ(ierr);
150   ierr = DMPlexGetCoordinateSection(dm, &coordSection);CHKERRQ(ierr);
151   ierr = PetscSectionCreate(PetscObjectComm((PetscObject)dm), &newCoordSection);CHKERRQ(ierr);
152   ierr = PetscSectionSetNumFields(newCoordSection, 1);CHKERRQ(ierr);
153   ierr = PetscSectionSetFieldComponents(newCoordSection, 0, dim);CHKERRQ(ierr);
154   ierr = PetscSectionSetChart(newCoordSection, vStartNew, vEndNew);CHKERRQ(ierr);
155   for (v = vStartNew; v < vEndNew; ++v) {
156     ierr = PetscSectionSetDof(newCoordSection, v, dim);CHKERRQ(ierr);
157     ierr = PetscSectionSetFieldDof(newCoordSection, v, 0, dim);CHKERRQ(ierr);
158   }
159   ierr = PetscSectionSetUp(newCoordSection);CHKERRQ(ierr);
160   ierr = DMPlexSetCoordinateSection(dmNew, newCoordSection);CHKERRQ(ierr);
161   ierr = PetscSectionGetStorageSize(newCoordSection, &coordSize);CHKERRQ(ierr);
162   ierr = VecCreate(PetscObjectComm((PetscObject)dm), &newCoordinates);CHKERRQ(ierr);
163   ierr = PetscObjectSetName((PetscObject) newCoordinates, "coordinates");CHKERRQ(ierr);
164   ierr = VecSetSizes(newCoordinates, coordSize, PETSC_DETERMINE);CHKERRQ(ierr);
165   ierr = VecSetFromOptions(newCoordinates);CHKERRQ(ierr);
166   ierr = DMSetCoordinatesLocal(dmNew, newCoordinates);CHKERRQ(ierr);
167   ierr = DMGetCoordinatesLocal(dm, &coordinates);CHKERRQ(ierr);
168   ierr = VecGetArray(coordinates, &coords);CHKERRQ(ierr);
169   ierr = VecGetArray(newCoordinates, &newCoords);CHKERRQ(ierr);
170   for (v = vStart; v < vEnd; ++v) {
171     PetscInt dof, off, noff, d;
172 
173     ierr = PetscSectionGetDof(coordSection, v, &dof);CHKERRQ(ierr);
174     ierr = PetscSectionGetOffset(coordSection, v, &off);CHKERRQ(ierr);
175     ierr = PetscSectionGetOffset(newCoordSection, DMPlexShiftPoint_Internal(v, depth, depthEnd, depthShift), &noff);CHKERRQ(ierr);
176     for (d = 0; d < dof; ++d) {
177       newCoords[noff+d] = coords[off+d];
178     }
179   }
180   ierr = VecRestoreArray(coordinates, &coords);CHKERRQ(ierr);
181   ierr = VecRestoreArray(newCoordinates, &newCoords);CHKERRQ(ierr);
182   ierr = VecDestroy(&newCoordinates);CHKERRQ(ierr);
183   ierr = PetscSectionDestroy(&newCoordSection);CHKERRQ(ierr);
184   ierr = PetscFree(depthEnd);CHKERRQ(ierr);
185   PetscFunctionReturn(0);
186 }
187 
188 #undef __FUNCT__
189 #define __FUNCT__ "DMPlexShiftSF_Internal"
190 static PetscErrorCode DMPlexShiftSF_Internal(DM dm, PetscInt depthShift[], DM dmNew)
191 {
192   PetscInt          *depthEnd;
193   PetscInt           depth = 0, d;
194   PetscSF            sfPoint, sfPointNew;
195   const PetscSFNode *remotePoints;
196   PetscSFNode       *gremotePoints;
197   const PetscInt    *localPoints;
198   PetscInt          *glocalPoints, *newLocation, *newRemoteLocation;
199   PetscInt           numRoots, numLeaves, l, pStart, pEnd, totShift = 0;
200   PetscMPIInt        numProcs;
201   PetscErrorCode     ierr;
202 
203   PetscFunctionBegin;
204   ierr = DMPlexGetDepth(dm, &depth);CHKERRQ(ierr);
205   ierr = PetscMalloc((depth+1) * sizeof(PetscInt), &depthEnd);CHKERRQ(ierr);
206   for (d = 0; d <= depth; ++d) {
207     totShift += depthShift[d];
208     ierr      = DMPlexGetDepthStratum(dm, d, NULL, &depthEnd[d]);CHKERRQ(ierr);
209   }
210   /* Step 9: Convert pointSF */
211   ierr = MPI_Comm_size(PetscObjectComm((PetscObject)dm), &numProcs);CHKERRQ(ierr);
212   ierr = DMGetPointSF(dm, &sfPoint);CHKERRQ(ierr);
213   ierr = DMGetPointSF(dmNew, &sfPointNew);CHKERRQ(ierr);
214   ierr = DMPlexGetChart(dm, &pStart, &pEnd);CHKERRQ(ierr);
215   ierr = PetscSFGetGraph(sfPoint, &numRoots, &numLeaves, &localPoints, &remotePoints);CHKERRQ(ierr);
216   if (numRoots >= 0) {
217     ierr = PetscMalloc2(numRoots,PetscInt,&newLocation,pEnd-pStart,PetscInt,&newRemoteLocation);CHKERRQ(ierr);
218     for (l=0; l<numRoots; l++) newLocation[l] = DMPlexShiftPoint_Internal(l, depth, depthEnd, depthShift);
219     ierr = PetscSFBcastBegin(sfPoint, MPIU_INT, newLocation, newRemoteLocation);CHKERRQ(ierr);
220     ierr = PetscSFBcastEnd(sfPoint, MPIU_INT, newLocation, newRemoteLocation);CHKERRQ(ierr);
221     ierr = PetscMalloc(numLeaves * sizeof(PetscInt),    &glocalPoints);CHKERRQ(ierr);
222     ierr = PetscMalloc(numLeaves * sizeof(PetscSFNode), &gremotePoints);CHKERRQ(ierr);
223     for (l = 0; l < numLeaves; ++l) {
224       glocalPoints[l]        = DMPlexShiftPoint_Internal(localPoints[l], depth, depthEnd, depthShift);
225       gremotePoints[l].rank  = remotePoints[l].rank;
226       gremotePoints[l].index = newRemoteLocation[localPoints[l]];
227     }
228     ierr = PetscFree2(newLocation,newRemoteLocation);CHKERRQ(ierr);
229     ierr = PetscSFSetGraph(sfPointNew, numRoots + totShift, numLeaves, glocalPoints, PETSC_OWN_POINTER, gremotePoints, PETSC_OWN_POINTER);CHKERRQ(ierr);
230   }
231   ierr = PetscFree(depthEnd);CHKERRQ(ierr);
232   PetscFunctionReturn(0);
233 }
234 
235 #undef __FUNCT__
236 #define __FUNCT__ "DMPlexShiftLabels_Internal"
237 static PetscErrorCode DMPlexShiftLabels_Internal(DM dm, PetscInt depthShift[], DM dmNew)
238 {
239   PetscSF            sfPoint;
240   DMLabel            vtkLabel, ghostLabel;
241   PetscInt          *depthEnd;
242   const PetscSFNode *leafRemote;
243   const PetscInt    *leafLocal;
244   PetscInt           depth = 0, d, numLeaves, numLabels, l, cStart, cEnd, c, fStart, fEnd, f;
245   PetscMPIInt        rank;
246   PetscErrorCode     ierr;
247 
248   PetscFunctionBegin;
249   ierr = DMPlexGetDepth(dm, &depth);CHKERRQ(ierr);
250   ierr = PetscMalloc((depth+1) * sizeof(PetscInt), &depthEnd);CHKERRQ(ierr);
251   for (d = 0; d <= depth; ++d) {
252     ierr = DMPlexGetDepthStratum(dm, d, NULL, &depthEnd[d]);CHKERRQ(ierr);
253   }
254   /* Step 10: Convert labels */
255   ierr = DMPlexGetNumLabels(dm, &numLabels);CHKERRQ(ierr);
256   for (l = 0; l < numLabels; ++l) {
257     DMLabel         label, newlabel;
258     const char     *lname;
259     PetscBool       isDepth;
260     IS              valueIS;
261     const PetscInt *values;
262     PetscInt        numValues, val;
263 
264     ierr = DMPlexGetLabelName(dm, l, &lname);CHKERRQ(ierr);
265     ierr = PetscStrcmp(lname, "depth", &isDepth);CHKERRQ(ierr);
266     if (isDepth) continue;
267     ierr = DMPlexCreateLabel(dmNew, lname);CHKERRQ(ierr);
268     ierr = DMPlexGetLabel(dm, lname, &label);CHKERRQ(ierr);
269     ierr = DMPlexGetLabel(dmNew, lname, &newlabel);CHKERRQ(ierr);
270     ierr = DMLabelGetValueIS(label, &valueIS);CHKERRQ(ierr);
271     ierr = ISGetLocalSize(valueIS, &numValues);CHKERRQ(ierr);
272     ierr = ISGetIndices(valueIS, &values);CHKERRQ(ierr);
273     for (val = 0; val < numValues; ++val) {
274       IS              pointIS;
275       const PetscInt *points;
276       PetscInt        numPoints, p;
277 
278       ierr = DMLabelGetStratumIS(label, values[val], &pointIS);CHKERRQ(ierr);
279       ierr = ISGetLocalSize(pointIS, &numPoints);CHKERRQ(ierr);
280       ierr = ISGetIndices(pointIS, &points);CHKERRQ(ierr);
281       for (p = 0; p < numPoints; ++p) {
282         const PetscInt newpoint = DMPlexShiftPoint_Internal(points[p], depth, depthEnd, depthShift);
283 
284         ierr = DMLabelSetValue(newlabel, newpoint, values[val]);CHKERRQ(ierr);
285       }
286       ierr = ISRestoreIndices(pointIS, &points);CHKERRQ(ierr);
287       ierr = ISDestroy(&pointIS);CHKERRQ(ierr);
288     }
289     ierr = ISRestoreIndices(valueIS, &values);CHKERRQ(ierr);
290     ierr = ISDestroy(&valueIS);CHKERRQ(ierr);
291   }
292   ierr = PetscFree(depthEnd);CHKERRQ(ierr);
293   /* Step 11: Make label for output (vtk) and to mark ghost points (ghost) */
294   ierr = MPI_Comm_rank(PetscObjectComm((PetscObject)dm), &rank);CHKERRQ(ierr);
295   ierr = DMGetPointSF(dm, &sfPoint);CHKERRQ(ierr);
296   ierr = DMPlexGetHeightStratum(dm, 0, &cStart, &cEnd);CHKERRQ(ierr);
297   ierr = PetscSFGetGraph(sfPoint, NULL, &numLeaves, &leafLocal, &leafRemote);CHKERRQ(ierr);
298   ierr = DMPlexCreateLabel(dmNew, "vtk");CHKERRQ(ierr);
299   ierr = DMPlexCreateLabel(dmNew, "ghost");CHKERRQ(ierr);
300   ierr = DMPlexGetLabel(dmNew, "vtk", &vtkLabel);CHKERRQ(ierr);
301   ierr = DMPlexGetLabel(dmNew, "ghost", &ghostLabel);CHKERRQ(ierr);
302   for (l = 0, c = cStart; l < numLeaves && c < cEnd; ++l, ++c) {
303     for (; c < leafLocal[l] && c < cEnd; ++c) {
304       ierr = DMLabelSetValue(vtkLabel, c, 1);CHKERRQ(ierr);
305     }
306     if (leafLocal[l] >= cEnd) break;
307     if (leafRemote[l].rank == rank) {
308       ierr = DMLabelSetValue(vtkLabel, c, 1);CHKERRQ(ierr);
309     } else {
310       ierr = DMLabelSetValue(ghostLabel, c, 2);CHKERRQ(ierr);
311     }
312   }
313   for (; c < cEnd; ++c) {
314     ierr = DMLabelSetValue(vtkLabel, c, 1);CHKERRQ(ierr);
315   }
316   if (0) {
317     ierr = PetscViewerASCIISynchronizedAllow(PETSC_VIEWER_STDOUT_WORLD, PETSC_TRUE);CHKERRQ(ierr);
318     ierr = DMLabelView(vtkLabel, PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
319     ierr = PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
320   }
321   ierr = DMPlexGetHeightStratum(dmNew, 1, &fStart, &fEnd);CHKERRQ(ierr);
322   for (f = fStart; f < fEnd; ++f) {
323     PetscInt numCells;
324 
325     ierr = DMPlexGetSupportSize(dmNew, f, &numCells);CHKERRQ(ierr);
326     if (numCells < 2) {
327       ierr = DMLabelSetValue(ghostLabel, f, 1);CHKERRQ(ierr);
328     } else {
329       const PetscInt *cells = NULL;
330       PetscInt        vA, vB;
331 
332       ierr = DMPlexGetSupport(dmNew, f, &cells);CHKERRQ(ierr);
333       ierr = DMLabelGetValue(vtkLabel, cells[0], &vA);CHKERRQ(ierr);
334       ierr = DMLabelGetValue(vtkLabel, cells[1], &vB);CHKERRQ(ierr);
335       if (!vA && !vB) {ierr = DMLabelSetValue(ghostLabel, f, 1);CHKERRQ(ierr);}
336     }
337   }
338   if (0) {
339     ierr = PetscViewerASCIISynchronizedAllow(PETSC_VIEWER_STDOUT_WORLD, PETSC_TRUE);CHKERRQ(ierr);
340     ierr = DMLabelView(ghostLabel, PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
341     ierr = PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
342   }
343   PetscFunctionReturn(0);
344 }
345 
346 #undef __FUNCT__
347 #define __FUNCT__ "DMPlexConstructGhostCells_Internal"
348 static PetscErrorCode DMPlexConstructGhostCells_Internal(DM dm, DMLabel label, PetscInt *numGhostCells, DM gdm)
349 {
350   IS              valueIS;
351   const PetscInt *values;
352   PetscInt       *depthShift;
353   PetscInt        depth = 0, numFS, fs, ghostCell, cEnd, c;
354   PetscErrorCode  ierr;
355 
356   PetscFunctionBegin;
357   /* Count ghost cells */
358   ierr = DMLabelGetValueIS(label, &valueIS);CHKERRQ(ierr);
359   ierr = ISGetLocalSize(valueIS, &numFS);CHKERRQ(ierr);
360   ierr = ISGetIndices(valueIS, &values);CHKERRQ(ierr);
361 
362   *numGhostCells = 0;
363   for (fs = 0; fs < numFS; ++fs) {
364     PetscInt numBdFaces;
365 
366     ierr = DMLabelGetStratumSize(label, values[fs], &numBdFaces);CHKERRQ(ierr);
367 
368     *numGhostCells += numBdFaces;
369   }
370   ierr = DMPlexGetDepth(dm, &depth);CHKERRQ(ierr);
371   ierr = PetscMalloc((depth+1) * sizeof(PetscInt), &depthShift);CHKERRQ(ierr);
372   ierr = PetscMemzero(depthShift, (depth+1) * sizeof(PetscInt));CHKERRQ(ierr);
373   if (depth >= 0) depthShift[depth] = *numGhostCells;
374   ierr = DMPlexShiftSizes_Internal(dm, depthShift, gdm);CHKERRQ(ierr);
375   /* Step 3: Set cone/support sizes for new points */
376   ierr = DMPlexGetHeightStratum(dm, 0, NULL, &cEnd);CHKERRQ(ierr);
377   for (c = cEnd; c < cEnd + *numGhostCells; ++c) {
378     ierr = DMPlexSetConeSize(gdm, c, 1);CHKERRQ(ierr);
379   }
380   for (fs = 0; fs < numFS; ++fs) {
381     IS              faceIS;
382     const PetscInt *faces;
383     PetscInt        numFaces, f;
384 
385     ierr = DMLabelGetStratumIS(label, values[fs], &faceIS);CHKERRQ(ierr);
386     ierr = ISGetLocalSize(faceIS, &numFaces);CHKERRQ(ierr);
387     ierr = ISGetIndices(faceIS, &faces);CHKERRQ(ierr);
388     for (f = 0; f < numFaces; ++f) {
389       PetscInt size;
390 
391       ierr = DMPlexGetSupportSize(dm, faces[f], &size);CHKERRQ(ierr);
392       if (size != 1) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "DM has boundary face %d with %d support cells", faces[f], size);
393       ierr = DMPlexSetSupportSize(gdm, faces[f] + *numGhostCells, 2);CHKERRQ(ierr);
394     }
395     ierr = ISRestoreIndices(faceIS, &faces);CHKERRQ(ierr);
396     ierr = ISDestroy(&faceIS);CHKERRQ(ierr);
397   }
398   /* Step 4: Setup ghosted DM */
399   ierr = DMSetUp(gdm);CHKERRQ(ierr);
400   ierr = DMPlexShiftPoints_Internal(dm, depthShift, gdm);CHKERRQ(ierr);
401   /* Step 6: Set cones and supports for new points */
402   ghostCell = cEnd;
403   for (fs = 0; fs < numFS; ++fs) {
404     IS              faceIS;
405     const PetscInt *faces;
406     PetscInt        numFaces, f;
407 
408     ierr = DMLabelGetStratumIS(label, values[fs], &faceIS);CHKERRQ(ierr);
409     ierr = ISGetLocalSize(faceIS, &numFaces);CHKERRQ(ierr);
410     ierr = ISGetIndices(faceIS, &faces);CHKERRQ(ierr);
411     for (f = 0; f < numFaces; ++f, ++ghostCell) {
412       PetscInt newFace = faces[f] + *numGhostCells;
413 
414       ierr = DMPlexSetCone(gdm, ghostCell, &newFace);CHKERRQ(ierr);
415       ierr = DMPlexInsertSupport(gdm, newFace, 1, ghostCell);CHKERRQ(ierr);
416     }
417     ierr = ISRestoreIndices(faceIS, &faces);CHKERRQ(ierr);
418     ierr = ISDestroy(&faceIS);CHKERRQ(ierr);
419   }
420   ierr = ISRestoreIndices(valueIS, &values);CHKERRQ(ierr);
421   ierr = ISDestroy(&valueIS);CHKERRQ(ierr);
422   /* Step 7: Stratify */
423   ierr = DMPlexStratify(gdm);CHKERRQ(ierr);
424   ierr = DMPlexShiftCoordinates_Internal(dm, depthShift, gdm);CHKERRQ(ierr);
425   ierr = DMPlexShiftSF_Internal(dm, depthShift, gdm);CHKERRQ(ierr);
426   ierr = DMPlexShiftLabels_Internal(dm, depthShift, gdm);CHKERRQ(ierr);
427   ierr = PetscFree(depthShift);CHKERRQ(ierr);
428   PetscFunctionReturn(0);
429 }
430 
431 #undef __FUNCT__
432 #define __FUNCT__ "DMPlexConstructGhostCells"
433 /*@C
434   DMPlexConstructGhostCells - Construct ghost cells which connect to every boundary face
435 
436   Collective on dm
437 
438   Input Parameters:
439 + dm - The original DM
440 - labelName - The label specifying the boundary faces, or "Face Sets" if this is NULL
441 
442   Output Parameters:
443 + numGhostCells - The number of ghost cells added to the DM
444 - dmGhosted - The new DM
445 
446   Note: If no label exists of that name, one will be created marking all boundary faces
447 
448   Level: developer
449 
450 .seealso: DMCreate()
451 */
452 PetscErrorCode DMPlexConstructGhostCells(DM dm, const char labelName[], PetscInt *numGhostCells, DM *dmGhosted)
453 {
454   DM             gdm;
455   DMLabel        label;
456   const char    *name = labelName ? labelName : "Face Sets";
457   PetscInt       dim;
458   PetscErrorCode ierr;
459 
460   PetscFunctionBegin;
461   PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
462   PetscValidPointer(numGhostCells, 3);
463   PetscValidPointer(dmGhosted, 4);
464   ierr = DMCreate(PetscObjectComm((PetscObject)dm), &gdm);CHKERRQ(ierr);
465   ierr = DMSetType(gdm, DMPLEX);CHKERRQ(ierr);
466   ierr = DMPlexGetDimension(dm, &dim);CHKERRQ(ierr);
467   ierr = DMPlexSetDimension(gdm, dim);CHKERRQ(ierr);
468   ierr = DMPlexGetLabel(dm, name, &label);CHKERRQ(ierr);
469   if (!label) {
470     /* Get label for boundary faces */
471     ierr = DMPlexCreateLabel(dm, name);CHKERRQ(ierr);
472     ierr = DMPlexGetLabel(dm, name, &label);CHKERRQ(ierr);
473     ierr = DMPlexMarkBoundaryFaces(dm, label);CHKERRQ(ierr);
474   }
475   ierr = DMPlexConstructGhostCells_Internal(dm, label, numGhostCells, gdm);CHKERRQ(ierr);
476   ierr = DMSetFromOptions(gdm);CHKERRQ(ierr);
477   *dmGhosted = gdm;
478   PetscFunctionReturn(0);
479 }
480 
481 #undef __FUNCT__
482 #define __FUNCT__ "DMPlexConstructCohesiveCells_Internal"
483 static PetscErrorCode DMPlexConstructCohesiveCells_Internal(DM dm, DMLabel label, DM sdm)
484 {
485   MPI_Comm        comm;
486   IS              valueIS, *pointIS;
487   const PetscInt *values, **splitPoints;
488   PetscSection    coordSection;
489   Vec             coordinates;
490   PetscScalar    *coords;
491   PetscInt       *depthShift, *depthOffset, *pMaxNew, *numSplitPoints, *coneNew, *supportNew;
492   PetscInt        shift = 100, depth = 0, dep, dim, d, numSP = 0, sp, maxConeSize, maxSupportSize, numLabels, p, v;
493   PetscErrorCode  ierr;
494 
495   PetscFunctionBegin;
496   ierr = PetscObjectGetComm((PetscObject)dm,&comm);CHKERRQ(ierr);
497   ierr = DMPlexGetDimension(dm, &dim);CHKERRQ(ierr);
498   /* Count split points and add cohesive cells */
499   if (label) {
500     ierr = DMLabelGetValueIS(label, &valueIS);CHKERRQ(ierr);
501     ierr = ISGetLocalSize(valueIS, &numSP);CHKERRQ(ierr);
502     ierr = ISGetIndices(valueIS, &values);CHKERRQ(ierr);
503   }
504   ierr = DMPlexGetDepth(dm, &depth);CHKERRQ(ierr);
505   ierr = DMPlexGetMaxSizes(dm, &maxConeSize, &maxSupportSize);CHKERRQ(ierr);
506   ierr = PetscMalloc5(depth+1,PetscInt,&depthShift,depth+1,PetscInt,&depthOffset,depth+1,PetscInt,&pMaxNew,maxConeSize*3,PetscInt,&coneNew,maxSupportSize,PetscInt,&supportNew);CHKERRQ(ierr);
507   ierr = PetscMalloc3(depth+1,IS,&pointIS,depth+1,PetscInt,&numSplitPoints,depth+1,const PetscInt*,&splitPoints);CHKERRQ(ierr);
508   ierr = PetscMemzero(depthShift, (depth+1) * sizeof(PetscInt));CHKERRQ(ierr);
509   for (d = 0; d <= depth; ++d) {
510     ierr              = DMPlexGetDepthStratum(dm, d, NULL, &pMaxNew[d]);CHKERRQ(ierr);
511     numSplitPoints[d] = 0;
512     splitPoints[d]    = NULL;
513     pointIS[d]        = NULL;
514   }
515   for (sp = 0; sp < numSP; ++sp) {
516     const PetscInt dep = values[sp];
517 
518     if ((dep < 0) || (dep > depth)) continue;
519     ierr = DMLabelGetStratumSize(label, dep, &depthShift[dep]);CHKERRQ(ierr);
520     ierr = DMLabelGetStratumIS(label, dep, &pointIS[dep]);CHKERRQ(ierr);
521     if (pointIS[dep]) {
522       ierr = ISGetLocalSize(pointIS[dep], &numSplitPoints[dep]);CHKERRQ(ierr);
523       ierr = ISGetIndices(pointIS[dep], &splitPoints[dep]);CHKERRQ(ierr);
524     }
525   }
526   if (depth >= 0) {
527     /* Calculate number of additional points */
528     depthShift[depth] = depthShift[depth-1]; /* There is a cohesive cell for every split face   */
529     depthShift[1]    += depthShift[0];       /* There is a cohesive edge for every split vertex */
530     /* Calculate hybrid bound for each dimension */
531     pMaxNew[0] += depthShift[depth];
532     if (depth > 1) pMaxNew[dim-1] += depthShift[depth] + depthShift[0];
533     if (depth > 2) pMaxNew[1]     += depthShift[depth] + depthShift[0] + depthShift[dim-1];
534 
535     /* Calculate point offset for each dimension */
536     depthOffset[depth] = 0;
537     depthOffset[0]     = depthOffset[depth] + depthShift[depth];
538     if (depth > 1) depthOffset[dim-1] = depthOffset[0]     + depthShift[0];
539     if (depth > 2) depthOffset[1]     = depthOffset[dim-1] + depthShift[dim-1];
540   }
541   ierr = DMPlexShiftSizes_Internal(dm, depthShift, sdm);CHKERRQ(ierr);
542   /* Step 3: Set cone/support sizes for new points */
543   for (dep = 0; dep <= depth; ++dep) {
544     for (p = 0; p < numSplitPoints[dep]; ++p) {
545       const PetscInt  oldp   = splitPoints[dep][p];
546       const PetscInt  newp   = depthOffset[dep] + oldp;
547       const PetscInt  splitp = pMaxNew[dep] + p;
548       const PetscInt *support;
549       PetscInt        coneSize, supportSize, q, e;
550 
551       ierr = DMPlexGetConeSize(dm, oldp, &coneSize);CHKERRQ(ierr);
552       ierr = DMPlexSetConeSize(sdm, splitp, coneSize);CHKERRQ(ierr);
553       ierr = DMPlexGetSupportSize(dm, oldp, &supportSize);CHKERRQ(ierr);
554       ierr = DMPlexSetSupportSize(sdm, splitp, supportSize);CHKERRQ(ierr);
555       if (dep == depth-1) {
556         const PetscInt ccell = pMaxNew[depth] + p;
557         /* Add cohesive cells, they are prisms */
558         ierr = DMPlexSetConeSize(sdm, ccell, 2 + coneSize);CHKERRQ(ierr);
559       } else if (dep == 0) {
560         const PetscInt cedge = pMaxNew[1] + (depthShift[1] - depthShift[0]) + p;
561 
562         ierr = DMPlexGetSupport(dm, oldp, &support);CHKERRQ(ierr);
563         /* Split old vertex: Edges in old split faces and new cohesive edge */
564         for (e = 0, q = 0; e < supportSize; ++e) {
565           PetscInt val;
566 
567           ierr = DMLabelGetValue(label, support[e], &val);CHKERRQ(ierr);
568           if ((val == 1) || (val == (shift + 1))) ++q;
569         }
570         ierr = DMPlexSetSupportSize(sdm, newp, q+1);CHKERRQ(ierr);
571         /* Split new vertex: Edges in new split faces and new cohesive edge */
572         for (e = 0, q = 0; e < supportSize; ++e) {
573           PetscInt val;
574 
575           ierr = DMLabelGetValue(label, support[e], &val);CHKERRQ(ierr);
576           if ((val == 1) || (val == -(shift + 1))) ++q;
577         }
578         ierr = DMPlexSetSupportSize(sdm, splitp, q+1);CHKERRQ(ierr);
579         /* Add cohesive edges */
580         ierr = DMPlexSetConeSize(sdm, cedge, 2);CHKERRQ(ierr);
581         /* Punt for now on support, you loop over closure, extract faces, check which ones are in the label */
582       } else if (dep == dim-2) {
583         ierr = DMPlexGetSupport(dm, oldp, &support);CHKERRQ(ierr);
584         /* Split old edge: Faces in positive side cells and old split faces */
585         for (e = 0, q = 0; e < supportSize; ++e) {
586           PetscInt val;
587 
588           ierr = DMLabelGetValue(label, support[e], &val);CHKERRQ(ierr);
589           if ((val == dim-1) || (val == (shift + dim-1))) ++q;
590         }
591         ierr = DMPlexSetSupportSize(sdm, newp, q);CHKERRQ(ierr);
592         /* Split new edge: Faces in negative side cells and new split faces */
593         for (e = 0, q = 0; e < supportSize; ++e) {
594           PetscInt val;
595 
596           ierr = DMLabelGetValue(label, support[e], &val);CHKERRQ(ierr);
597           if ((val == dim-1) || (val == -(shift + dim-1))) ++q;
598         }
599         ierr = DMPlexSetSupportSize(sdm, splitp, q);CHKERRQ(ierr);
600       }
601     }
602   }
603   /* Step 4: Setup split DM */
604   ierr = DMSetUp(sdm);CHKERRQ(ierr);
605   ierr = DMPlexShiftPoints_Internal(dm, depthShift, sdm);CHKERRQ(ierr);
606   /* Step 6: Set cones and supports for new points */
607   for (dep = 0; dep <= depth; ++dep) {
608     for (p = 0; p < numSplitPoints[dep]; ++p) {
609       const PetscInt  oldp   = splitPoints[dep][p];
610       const PetscInt  newp   = depthOffset[dep] + oldp;
611       const PetscInt  splitp = pMaxNew[dep] + p;
612       const PetscInt *cone, *support, *ornt;
613       PetscInt        coneSize, supportSize, q, v, e, s;
614 
615       ierr = DMPlexGetConeSize(dm, oldp, &coneSize);CHKERRQ(ierr);
616       ierr = DMPlexGetCone(dm, oldp, &cone);CHKERRQ(ierr);
617       ierr = DMPlexGetConeOrientation(dm, oldp, &ornt);CHKERRQ(ierr);
618       ierr = DMPlexGetSupportSize(dm, oldp, &supportSize);CHKERRQ(ierr);
619       ierr = DMPlexGetSupport(dm, oldp, &support);CHKERRQ(ierr);
620       if (dep == depth-1) {
621         const PetscInt  ccell = pMaxNew[depth] + p;
622         const PetscInt *supportF;
623 
624         /* Split face:       copy in old face to new face to start */
625         ierr = DMPlexGetSupport(sdm, newp,  &supportF);CHKERRQ(ierr);
626         ierr = DMPlexSetSupport(sdm, splitp, supportF);CHKERRQ(ierr);
627         /* Split old face:   old vertices/edges in cone so no change */
628         /* Split new face:   new vertices/edges in cone */
629         for (q = 0; q < coneSize; ++q) {
630           ierr = PetscFindInt(cone[q], numSplitPoints[dim-2], splitPoints[dim-2], &v);CHKERRQ(ierr);
631 
632           coneNew[2+q] = pMaxNew[dim-2] + v;
633         }
634         ierr = DMPlexSetCone(sdm, splitp, &coneNew[2]);CHKERRQ(ierr);
635         ierr = DMPlexSetConeOrientation(sdm, splitp, ornt);CHKERRQ(ierr);
636         /* Cohesive cell:    Old and new split face, then new cohesive edges */
637         coneNew[0] = newp;
638         coneNew[1] = splitp;
639         for (q = 0; q < coneSize; ++q) {
640           coneNew[2+q] = (pMaxNew[1] - pMaxNew[dim-2]) + (depthShift[1] - depthShift[0]) + coneNew[2+q];
641         }
642         ierr = DMPlexSetCone(sdm, ccell, coneNew);CHKERRQ(ierr);
643 
644 
645         for (s = 0; s < supportSize; ++s) {
646           PetscInt val;
647 
648           ierr = DMLabelGetValue(label, support[s], &val);CHKERRQ(ierr);
649           if (val < 0) {
650             /* Split old face:   Replace negative side cell with cohesive cell */
651             ierr = DMPlexInsertSupport(sdm, newp, s, ccell);CHKERRQ(ierr);
652           } else {
653             /* Split new face:   Replace positive side cell with cohesive cell */
654             ierr = DMPlexInsertSupport(sdm, splitp, s, ccell);CHKERRQ(ierr);
655           }
656         }
657       } else if (dep == 0) {
658         const PetscInt cedge = pMaxNew[1] + (depthShift[1] - depthShift[0]) + p;
659 
660         /* Split old vertex: Edges in old split faces and new cohesive edge */
661         for (e = 0, q = 0; e < supportSize; ++e) {
662           PetscInt val;
663 
664           ierr = DMLabelGetValue(label, support[e], &val);CHKERRQ(ierr);
665           if ((val == 1) || (val == (shift + 1))) {
666             supportNew[q++] = depthOffset[1] + support[e];
667           }
668         }
669         supportNew[q] = cedge;
670 
671         ierr = DMPlexSetSupport(sdm, newp, supportNew);CHKERRQ(ierr);
672         /* Split new vertex: Edges in new split faces and new cohesive edge */
673         for (e = 0, q = 0; e < supportSize; ++e) {
674           PetscInt val, edge;
675 
676           ierr = DMLabelGetValue(label, support[e], &val);CHKERRQ(ierr);
677           if (val == 1) {
678             ierr = PetscFindInt(support[e], numSplitPoints[1], splitPoints[1], &edge);CHKERRQ(ierr);
679             if (edge < 0) SETERRQ1(comm, PETSC_ERR_ARG_WRONG, "Edge %d is not a split edge", support[e]);
680             supportNew[q++] = pMaxNew[1] + edge;
681           } else if (val == -(shift + 1)) {
682             supportNew[q++] = depthOffset[1] + support[e];
683           }
684         }
685         supportNew[q] = cedge;
686         ierr          = DMPlexSetSupport(sdm, splitp, supportNew);CHKERRQ(ierr);
687         /* Cohesive edge:    Old and new split vertex, punting on support */
688         coneNew[0] = newp;
689         coneNew[1] = splitp;
690         ierr       = DMPlexSetCone(sdm, cedge, coneNew);CHKERRQ(ierr);
691       } else if (dep == dim-2) {
692         /* Split old edge:   old vertices in cone so no change */
693         /* Split new edge:   new vertices in cone */
694         for (q = 0; q < coneSize; ++q) {
695           ierr = PetscFindInt(cone[q], numSplitPoints[dim-3], splitPoints[dim-3], &v);CHKERRQ(ierr);
696 
697           coneNew[q] = pMaxNew[dim-3] + v;
698         }
699         ierr = DMPlexSetCone(sdm, splitp, coneNew);CHKERRQ(ierr);
700         /* Split old edge: Faces in positive side cells and old split faces */
701         for (e = 0, q = 0; e < supportSize; ++e) {
702           PetscInt val;
703 
704           ierr = DMLabelGetValue(label, support[e], &val);CHKERRQ(ierr);
705           if ((val == dim-1) || (val == (shift + dim-1))) {
706             supportNew[q++] = depthOffset[dim-1] + support[e];
707           }
708         }
709         ierr = DMPlexSetSupport(sdm, newp, supportNew);CHKERRQ(ierr);
710         /* Split new edge: Faces in negative side cells and new split faces */
711         for (e = 0, q = 0; e < supportSize; ++e) {
712           PetscInt val, face;
713 
714           ierr = DMLabelGetValue(label, support[e], &val);CHKERRQ(ierr);
715           if (val == dim-1) {
716             ierr = PetscFindInt(support[e], numSplitPoints[dim-1], splitPoints[dim-1], &face);CHKERRQ(ierr);
717             if (face < 0) SETERRQ1(comm, PETSC_ERR_ARG_WRONG, "Face %d is not a split face", support[e]);
718             supportNew[q++] = pMaxNew[dim-1] + face;
719           } else if (val == -(shift + dim-1)) {
720             supportNew[q++] = depthOffset[dim-1] + support[e];
721           }
722         }
723         ierr = DMPlexSetSupport(sdm, splitp, supportNew);CHKERRQ(ierr);
724       }
725     }
726   }
727   /* Step 6b: Replace split points in negative side cones */
728   for (sp = 0; sp < numSP; ++sp) {
729     PetscInt        dep = values[sp];
730     IS              pIS;
731     PetscInt        numPoints;
732     const PetscInt *points;
733 
734     if (dep >= 0) continue;
735     ierr = DMLabelGetStratumIS(label, dep, &pIS);CHKERRQ(ierr);
736     if (!pIS) continue;
737     dep  = -dep - shift;
738     ierr = ISGetLocalSize(pIS, &numPoints);CHKERRQ(ierr);
739     ierr = ISGetIndices(pIS, &points);CHKERRQ(ierr);
740     for (p = 0; p < numPoints; ++p) {
741       const PetscInt  oldp = points[p];
742       const PetscInt  newp = depthOffset[dep] + oldp;
743       const PetscInt *cone;
744       PetscInt        coneSize, c;
745       PetscBool       replaced = PETSC_FALSE;
746 
747       /* Negative edge: replace split vertex */
748       /* Negative cell: replace split face */
749       ierr = DMPlexGetConeSize(sdm, newp, &coneSize);CHKERRQ(ierr);
750       ierr = DMPlexGetCone(sdm, newp, &cone);CHKERRQ(ierr);
751       for (c = 0; c < coneSize; ++c) {
752         const PetscInt coldp = cone[c] - depthOffset[dep-1];
753         PetscInt       csplitp, cp, val;
754 
755         ierr = DMLabelGetValue(label, coldp, &val);CHKERRQ(ierr);
756         if (val == dep-1) {
757           ierr = PetscFindInt(coldp, numSplitPoints[dep-1], splitPoints[dep-1], &cp);CHKERRQ(ierr);
758           if (cp < 0) SETERRQ2(comm, PETSC_ERR_ARG_WRONG, "Point %d is not a split point of dimension %d", oldp, dep-1);
759           csplitp  = pMaxNew[dep-1] + cp;
760           ierr     = DMPlexInsertCone(sdm, newp, c, csplitp);CHKERRQ(ierr);
761           replaced = PETSC_TRUE;
762         }
763       }
764       if (!replaced) SETERRQ1(comm, PETSC_ERR_ARG_WRONG, "The cone of point %d does not contain split points", oldp);
765     }
766     ierr = ISRestoreIndices(pIS, &points);CHKERRQ(ierr);
767     ierr = ISDestroy(&pIS);CHKERRQ(ierr);
768   }
769   /* Step 7: Stratify */
770   ierr = DMPlexStratify(sdm);CHKERRQ(ierr);
771   /* Step 8: Coordinates */
772   ierr = DMPlexShiftCoordinates_Internal(dm, depthShift, sdm);CHKERRQ(ierr);
773   ierr = DMPlexGetCoordinateSection(sdm, &coordSection);CHKERRQ(ierr);
774   ierr = DMGetCoordinatesLocal(sdm, &coordinates);CHKERRQ(ierr);
775   ierr = VecGetArray(coordinates, &coords);CHKERRQ(ierr);
776   for (v = 0; v < (numSplitPoints ? numSplitPoints[0] : 0); ++v) {
777     const PetscInt newp   = depthOffset[0] + splitPoints[0][v];
778     const PetscInt splitp = pMaxNew[0] + v;
779     PetscInt       dof, off, soff, d;
780 
781     ierr = PetscSectionGetDof(coordSection, newp, &dof);CHKERRQ(ierr);
782     ierr = PetscSectionGetOffset(coordSection, newp, &off);CHKERRQ(ierr);
783     ierr = PetscSectionGetOffset(coordSection, splitp, &soff);CHKERRQ(ierr);
784     for (d = 0; d < dof; ++d) coords[soff+d] = coords[off+d];
785   }
786   ierr = VecRestoreArray(coordinates, &coords);CHKERRQ(ierr);
787   /* Step 9: SF, if I can figure this out we can split the mesh in parallel */
788   ierr = DMPlexShiftSF_Internal(dm, depthShift, sdm);CHKERRQ(ierr);
789   /* Step 10: Labels */
790   ierr = DMPlexShiftLabels_Internal(dm, depthShift, sdm);CHKERRQ(ierr);
791   ierr = DMPlexGetNumLabels(sdm, &numLabels);CHKERRQ(ierr);
792   for (dep = 0; dep <= depth; ++dep) {
793     for (p = 0; p < numSplitPoints[dep]; ++p) {
794       const PetscInt newp   = depthOffset[dep] + splitPoints[dep][p];
795       const PetscInt splitp = pMaxNew[dep] + p;
796       PetscInt       l;
797 
798       for (l = 0; l < numLabels; ++l) {
799         DMLabel     mlabel;
800         const char *lname;
801         PetscInt    val;
802 
803         ierr = DMPlexGetLabelName(sdm, l, &lname);CHKERRQ(ierr);
804         ierr = DMPlexGetLabel(sdm, lname, &mlabel);CHKERRQ(ierr);
805         ierr = DMLabelGetValue(mlabel, newp, &val);CHKERRQ(ierr);
806         if (val >= 0) {
807           ierr = DMLabelSetValue(mlabel, splitp, val);CHKERRQ(ierr);
808           if (dep == 0) {
809             const PetscInt cedge = pMaxNew[1] + (depthShift[1] - depthShift[0]) + p;
810             ierr = DMLabelSetValue(mlabel, cedge, val);CHKERRQ(ierr);
811           }
812         }
813       }
814     }
815   }
816   for (sp = 0; sp < numSP; ++sp) {
817     const PetscInt dep = values[sp];
818 
819     if ((dep < 0) || (dep > depth)) continue;
820     if (pointIS[dep]) {ierr = ISRestoreIndices(pointIS[dep], &splitPoints[dep]);CHKERRQ(ierr);}
821     ierr = ISDestroy(&pointIS[dep]);CHKERRQ(ierr);
822   }
823   if (label) {
824     ierr = ISRestoreIndices(valueIS, &values);CHKERRQ(ierr);
825     ierr = ISDestroy(&valueIS);CHKERRQ(ierr);
826   }
827   ierr = PetscFree5(depthShift, depthOffset, pMaxNew, coneNew, supportNew);CHKERRQ(ierr);
828   ierr = PetscFree3(pointIS, numSplitPoints, splitPoints);CHKERRQ(ierr);
829   PetscFunctionReturn(0);
830 }
831 
832 #undef __FUNCT__
833 #define __FUNCT__ "DMPlexConstructCohesiveCells"
834 /*@C
835   DMPlexConstructCohesiveCells - Construct cohesive cells which split the face along an internal interface
836 
837   Collective on dm
838 
839   Input Parameters:
840 + dm - The original DM
841 - labelName - The label specifying the boundary faces (this could be auto-generated)
842 
843   Output Parameters:
844 - dmSplit - The new DM
845 
846   Level: developer
847 
848 .seealso: DMCreate(), DMLabelCohesiveComplete()
849 @*/
850 PetscErrorCode DMPlexConstructCohesiveCells(DM dm, DMLabel label, DM *dmSplit)
851 {
852   DM             sdm;
853   PetscInt       dim;
854   PetscErrorCode ierr;
855 
856   PetscFunctionBegin;
857   PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
858   PetscValidPointer(dmSplit, 4);
859   ierr = DMCreate(PetscObjectComm((PetscObject)dm), &sdm);CHKERRQ(ierr);
860   ierr = DMSetType(sdm, DMPLEX);CHKERRQ(ierr);
861   ierr = DMPlexGetDimension(dm, &dim);CHKERRQ(ierr);
862   ierr = DMPlexSetDimension(sdm, dim);CHKERRQ(ierr);
863   switch (dim) {
864   case 2:
865   case 3:
866     ierr = DMPlexConstructCohesiveCells_Internal(dm, label, sdm);CHKERRQ(ierr);
867     break;
868   default:
869     SETERRQ1(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_OUTOFRANGE, "Cannot construct cohesive cells for dimension %d", dim);
870   }
871   *dmSplit = sdm;
872   PetscFunctionReturn(0);
873 }
874 
875 #undef __FUNCT__
876 #define __FUNCT__ "DMLabelCohesiveComplete"
877 /*@
878   DMLabelCohesiveComplete - Starting with a label marking vertices on an internal surface, we add all other mesh pieces
879   to complete the surface
880 
881   Input Parameters:
882 + dm - The DM
883 - label - A DMLabel marking the surface vertices
884 
885   Output Parameter:
886 . label - A DMLabel marking all surface points
887 
888   Level: developer
889 
890 .seealso: DMPlexConstructCohesiveCells()
891 @*/
892 PetscErrorCode DMLabelCohesiveComplete(DM dm, DMLabel label)
893 {
894   IS              dimIS;
895   const PetscInt *points;
896   PetscInt        shift = 100, dim, dep, cStart, cEnd, numPoints, p, val;
897   PetscErrorCode  ierr;
898 
899   PetscFunctionBegin;
900   ierr = DMPlexGetDimension(dm, &dim);CHKERRQ(ierr);
901   /* Cell orientation for face gives the side of the fault */
902   ierr = DMLabelGetStratumIS(label, dim-1, &dimIS);CHKERRQ(ierr);
903   if (!dimIS) PetscFunctionReturn(0);
904   ierr = ISGetLocalSize(dimIS, &numPoints);CHKERRQ(ierr);
905   ierr = ISGetIndices(dimIS, &points);CHKERRQ(ierr);
906   for (p = 0; p < numPoints; ++p) {
907     const PetscInt *support;
908     PetscInt        supportSize, s;
909 
910     ierr = DMPlexGetSupportSize(dm, points[p], &supportSize);CHKERRQ(ierr);
911     if (supportSize != 2) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Split face %d has %d != 2 supports", points[p], supportSize);
912     ierr = DMPlexGetSupport(dm, points[p], &support);CHKERRQ(ierr);
913     for (s = 0; s < supportSize; ++s) {
914       const PetscInt *cone, *ornt;
915       PetscInt        coneSize, c;
916       PetscBool       pos = PETSC_TRUE;
917 
918       ierr = DMPlexGetConeSize(dm, support[s], &coneSize);CHKERRQ(ierr);
919       ierr = DMPlexGetCone(dm, support[s], &cone);CHKERRQ(ierr);
920       ierr = DMPlexGetConeOrientation(dm, support[s], &ornt);CHKERRQ(ierr);
921       for (c = 0; c < coneSize; ++c) {
922         if (cone[c] == points[p]) {
923           if (ornt[c] >= 0) {
924             ierr = DMLabelSetValue(label, support[s],   shift+dim);CHKERRQ(ierr);
925           } else {
926             ierr = DMLabelSetValue(label, support[s], -(shift+dim));CHKERRQ(ierr);
927             pos  = PETSC_FALSE;
928           }
929           break;
930         }
931       }
932       if (c == coneSize) SETERRQ1(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Cell split face %d support does not have it in the cone", points[p]);
933       /* Put faces touching the fault in the label */
934       for (c = 0; c < coneSize; ++c) {
935         const PetscInt point = cone[c];
936 
937         ierr = DMLabelGetValue(label, point, &val);CHKERRQ(ierr);
938         if (val == -1) {
939           PetscInt *closure = NULL;
940           PetscInt  closureSize, cl;
941 
942           ierr = DMPlexGetTransitiveClosure(dm, point, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
943           for (cl = 0; cl < closureSize*2; cl += 2) {
944             const PetscInt clp = closure[cl];
945 
946             ierr = DMLabelGetValue(label, clp, &val);CHKERRQ(ierr);
947             if ((val >= 0) && (val < dim-1)) {
948               ierr = DMLabelSetValue(label, point, pos == PETSC_TRUE ? shift+dim-1 : -(shift+dim-1));CHKERRQ(ierr);
949               break;
950             }
951           }
952           ierr = DMPlexRestoreTransitiveClosure(dm, point, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
953         }
954       }
955     }
956   }
957   ierr = ISRestoreIndices(dimIS, &points);CHKERRQ(ierr);
958   ierr = ISDestroy(&dimIS);CHKERRQ(ierr);
959   /* Search for other cells/faces/edges connected to the fault by a vertex */
960   ierr = DMPlexGetHeightStratum(dm, 0, &cStart, &cEnd);CHKERRQ(ierr);
961   ierr = DMLabelGetStratumIS(label, 0, &dimIS);CHKERRQ(ierr);
962   if (!dimIS) PetscFunctionReturn(0);
963   ierr = ISGetLocalSize(dimIS, &numPoints);CHKERRQ(ierr);
964   ierr = ISGetIndices(dimIS, &points);CHKERRQ(ierr);
965   for (p = 0; p < numPoints; ++p) {
966     PetscInt *star = NULL;
967     PetscInt  starSize, s;
968     PetscInt  again = 1;  /* 0: Finished 1: Keep iterating after a change 2: No change */
969 
970     /* First mark cells connected to the fault */
971     ierr = DMPlexGetTransitiveClosure(dm, points[p], PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
972     while (again) {
973       if (again > 1) SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "Could not classify all cells connected to the fault");
974       again = 0;
975       for (s = 0; s < starSize*2; s += 2) {
976         const PetscInt  point = star[s];
977         const PetscInt *cone;
978         PetscInt        coneSize, c;
979 
980         if ((point < cStart) || (point >= cEnd)) continue;
981         ierr = DMLabelGetValue(label, point, &val);CHKERRQ(ierr);
982         if (val != -1) continue;
983         again = 2;
984         ierr  = DMPlexGetConeSize(dm, point, &coneSize);CHKERRQ(ierr);
985         ierr  = DMPlexGetCone(dm, point, &cone);CHKERRQ(ierr);
986         for (c = 0; c < coneSize; ++c) {
987           ierr = DMLabelGetValue(label, cone[c], &val);CHKERRQ(ierr);
988           if (val != -1) {
989             if (abs(val) < shift) SETERRQ3(PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "Face %d on cell %d has an invalid label %d", cone[c], point, val);
990             if (val > 0) {
991               ierr = DMLabelSetValue(label, point,   shift+dim);CHKERRQ(ierr);
992             } else {
993               ierr = DMLabelSetValue(label, point, -(shift+dim));CHKERRQ(ierr);
994             }
995             again = 1;
996             break;
997           }
998         }
999       }
1000     }
1001     /* Classify the rest by cell membership */
1002     for (s = 0; s < starSize*2; s += 2) {
1003       const PetscInt point = star[s];
1004 
1005       ierr = DMLabelGetValue(label, point, &val);CHKERRQ(ierr);
1006       if (val == -1) {
1007         PetscInt  *sstar = NULL;
1008         PetscInt   sstarSize, ss;
1009         PetscBool  marked = PETSC_FALSE;
1010 
1011         ierr = DMPlexGetTransitiveClosure(dm, point, PETSC_FALSE, &sstarSize, &sstar);CHKERRQ(ierr);
1012         for (ss = 0; ss < sstarSize*2; ss += 2) {
1013           const PetscInt spoint = sstar[ss];
1014 
1015           if ((spoint < cStart) || (spoint >= cEnd)) continue;
1016           ierr = DMLabelGetValue(label, spoint, &val);CHKERRQ(ierr);
1017           if (val == -1) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "Cell %d in star of %d does not have a valid label", spoint, point);
1018           ierr = DMPlexGetLabelValue(dm, "depth", point, &dep);CHKERRQ(ierr);
1019           if (val > 0) {
1020             ierr = DMLabelSetValue(label, point,   shift+dep);CHKERRQ(ierr);
1021           } else {
1022             ierr = DMLabelSetValue(label, point, -(shift+dep));CHKERRQ(ierr);
1023           }
1024           marked = PETSC_TRUE;
1025           break;
1026         }
1027         ierr = DMPlexRestoreTransitiveClosure(dm, point, PETSC_FALSE, &sstarSize, &sstar);CHKERRQ(ierr);
1028         if (!marked) SETERRQ1(PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "Point %d could not be classified", point);
1029       }
1030     }
1031     ierr = DMPlexRestoreTransitiveClosure(dm, points[p], PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
1032   }
1033   ierr = ISRestoreIndices(dimIS, &points);CHKERRQ(ierr);
1034   ierr = ISDestroy(&dimIS);CHKERRQ(ierr);
1035   PetscFunctionReturn(0);
1036 }
1037 
1038 #undef __FUNCT__
1039 #define __FUNCT__ "DMPlexMarkSubmesh_Uninterpolated"
1040 /* Here we need the explicit assumption that:
1041 
1042      For any marked cell, the marked vertices constitute a single face
1043 */
1044 static PetscErrorCode DMPlexMarkSubmesh_Uninterpolated(DM dm, DMLabel vertexLabel, DMLabel subpointMap, PetscInt *numFaces, PetscInt *nFV, DM subdm)
1045 {
1046   IS               subvertexIS;
1047   const PetscInt  *subvertices;
1048   PetscInt        *pStart, *pEnd, *pMax;
1049   PetscInt         depth, dim, d, numSubVerticesInitial = 0, v;
1050   PetscErrorCode   ierr;
1051 
1052   PetscFunctionBegin;
1053   *numFaces = 0;
1054   *nFV      = 0;
1055   ierr = DMPlexGetDepth(dm, &depth);CHKERRQ(ierr);
1056   ierr = DMPlexGetDimension(dm, &dim);CHKERRQ(ierr);
1057   ierr = PetscMalloc3(dim+1,PetscInt,&pStart,dim+1,PetscInt,&pEnd,dim+1,PetscInt,&pMax);CHKERRQ(ierr);
1058   ierr = DMPlexGetHybridBounds(dm, &pMax[depth], depth>1 ? &pMax[depth-1] : NULL, depth > 2 ? &pMax[1] : NULL, &pMax[0]);CHKERRQ(ierr);
1059   for (d = 0; d <= depth; ++d) {
1060     ierr = DMPlexGetDepthStratum(dm, d, &pStart[d], &pEnd[d]);CHKERRQ(ierr);
1061     if (pMax[d] >= 0) pEnd[d] = PetscMin(pEnd[d], pMax[d]);
1062   }
1063   /* Loop over initial vertices and mark all faces in the collective star() */
1064   ierr = DMLabelGetStratumIS(vertexLabel, 1, &subvertexIS);CHKERRQ(ierr);
1065   if (subvertexIS) {
1066     ierr = ISGetSize(subvertexIS, &numSubVerticesInitial);CHKERRQ(ierr);
1067     ierr = ISGetIndices(subvertexIS, &subvertices);CHKERRQ(ierr);
1068   }
1069   for (v = 0; v < numSubVerticesInitial; ++v) {
1070     const PetscInt vertex = subvertices[v];
1071     PetscInt      *star   = NULL;
1072     PetscInt       starSize, s, numCells = 0, c;
1073 
1074     ierr = DMPlexGetTransitiveClosure(dm, vertex, PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
1075     for (s = 0; s < starSize*2; s += 2) {
1076       const PetscInt point = star[s];
1077       if ((point >= pStart[depth]) && (point < pEnd[depth])) star[numCells++] = point;
1078     }
1079     for (c = 0; c < numCells; ++c) {
1080       const PetscInt cell    = star[c];
1081       PetscInt      *closure = NULL;
1082       PetscInt       closureSize, cl;
1083       PetscInt       cellLoc, numCorners = 0, faceSize = 0;
1084 
1085       ierr = DMLabelGetValue(subpointMap, cell, &cellLoc);CHKERRQ(ierr);
1086       if (cellLoc == 2) continue;
1087       if (cellLoc >= 0) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "Cell %d has dimension %d in the surface label", cell, cellLoc);
1088       ierr = DMPlexGetTransitiveClosure(dm, cell, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
1089       for (cl = 0; cl < closureSize*2; cl += 2) {
1090         const PetscInt point = closure[cl];
1091         PetscInt       vertexLoc;
1092 
1093         if ((point >= pStart[0]) && (point < pEnd[0])) {
1094           ++numCorners;
1095           ierr = DMLabelGetValue(vertexLabel, point, &vertexLoc);CHKERRQ(ierr);
1096           if (vertexLoc >= 0) closure[faceSize++] = point;
1097         }
1098       }
1099       if (!(*nFV)) {ierr = DMPlexGetNumFaceVertices_Internal(dm, dim, numCorners, nFV);CHKERRQ(ierr);}
1100       if (faceSize > *nFV) SETERRQ1(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Invalid submesh: Too many vertices %d of an element on the surface", faceSize);
1101       if (faceSize == *nFV) {
1102         ++(*numFaces);
1103         for (cl = 0; cl < faceSize; ++cl) {
1104           ierr = DMLabelSetValue(subpointMap, closure[cl], 0);CHKERRQ(ierr);
1105         }
1106         ierr = DMLabelSetValue(subpointMap, cell, 2);CHKERRQ(ierr);
1107       }
1108       ierr = DMPlexRestoreTransitiveClosure(dm, cell, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
1109     }
1110     ierr = DMPlexRestoreTransitiveClosure(dm, vertex, PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
1111   }
1112   if (subvertexIS) {
1113     ierr = ISRestoreIndices(subvertexIS, &subvertices);CHKERRQ(ierr);
1114   }
1115   ierr = ISDestroy(&subvertexIS);CHKERRQ(ierr);
1116   ierr = PetscFree3(pStart,pEnd,pMax);CHKERRQ(ierr);
1117   PetscFunctionReturn(0);
1118 }
1119 
1120 #undef __FUNCT__
1121 #define __FUNCT__ "DMPlexMarkSubmesh_Interpolated"
1122 static PetscErrorCode DMPlexMarkSubmesh_Interpolated(DM dm, DMLabel vertexLabel, DMLabel subpointMap, DM subdm)
1123 {
1124   IS               subvertexIS;
1125   const PetscInt  *subvertices;
1126   PetscInt        *pStart, *pEnd, *pMax;
1127   PetscInt         dim, d, numSubVerticesInitial = 0, v;
1128   PetscErrorCode   ierr;
1129 
1130   PetscFunctionBegin;
1131   ierr = DMPlexGetDimension(dm, &dim);CHKERRQ(ierr);
1132   ierr = PetscMalloc3(dim+1,PetscInt,&pStart,dim+1,PetscInt,&pEnd,dim+1,PetscInt,&pMax);CHKERRQ(ierr);
1133   ierr = DMPlexGetHybridBounds(dm, &pMax[dim], dim>1 ? &pMax[dim-1] : NULL, dim > 2 ? &pMax[1] : NULL, &pMax[0]);CHKERRQ(ierr);
1134   for (d = 0; d <= dim; ++d) {
1135     ierr = DMPlexGetDepthStratum(dm, d, &pStart[d], &pEnd[d]);CHKERRQ(ierr);
1136     if (pMax[d] >= 0) pEnd[d] = PetscMin(pEnd[d], pMax[d]);
1137   }
1138   /* Loop over initial vertices and mark all faces in the collective star() */
1139   ierr = DMLabelGetStratumIS(vertexLabel, 1, &subvertexIS);CHKERRQ(ierr);
1140   if (subvertexIS) {
1141     ierr = ISGetSize(subvertexIS, &numSubVerticesInitial);CHKERRQ(ierr);
1142     ierr = ISGetIndices(subvertexIS, &subvertices);CHKERRQ(ierr);
1143   }
1144   for (v = 0; v < numSubVerticesInitial; ++v) {
1145     const PetscInt vertex = subvertices[v];
1146     PetscInt      *star   = NULL;
1147     PetscInt       starSize, s, numFaces = 0, f;
1148 
1149     ierr = DMPlexGetTransitiveClosure(dm, vertex, PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
1150     for (s = 0; s < starSize*2; s += 2) {
1151       const PetscInt point = star[s];
1152       if ((point >= pStart[dim-1]) && (point < pEnd[dim-1])) star[numFaces++] = point;
1153     }
1154     for (f = 0; f < numFaces; ++f) {
1155       const PetscInt face    = star[f];
1156       PetscInt      *closure = NULL;
1157       PetscInt       closureSize, c;
1158       PetscInt       faceLoc;
1159 
1160       ierr = DMLabelGetValue(subpointMap, face, &faceLoc);CHKERRQ(ierr);
1161       if (faceLoc == dim-1) continue;
1162       if (faceLoc >= 0) SETERRQ2(PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "Face %d has dimension %d in the surface label", face, faceLoc);
1163       ierr = DMPlexGetTransitiveClosure(dm, face, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
1164       for (c = 0; c < closureSize*2; c += 2) {
1165         const PetscInt point = closure[c];
1166         PetscInt       vertexLoc;
1167 
1168         if ((point >= pStart[0]) && (point < pEnd[0])) {
1169           ierr = DMLabelGetValue(vertexLabel, point, &vertexLoc);CHKERRQ(ierr);
1170           if (vertexLoc < 0) break;
1171         }
1172       }
1173       if (c == closureSize*2) {
1174         const PetscInt *support;
1175         PetscInt        supportSize, s;
1176 
1177         for (c = 0; c < closureSize*2; c += 2) {
1178           const PetscInt point = closure[c];
1179 
1180           for (d = 0; d < dim; ++d) {
1181             if ((point >= pStart[d]) && (point < pEnd[d])) {
1182               ierr = DMLabelSetValue(subpointMap, point, d);CHKERRQ(ierr);
1183               break;
1184             }
1185           }
1186         }
1187         ierr = DMPlexGetSupportSize(dm, face, &supportSize);CHKERRQ(ierr);
1188         ierr = DMPlexGetSupport(dm, face, &support);CHKERRQ(ierr);
1189         for (s = 0; s < supportSize; ++s) {
1190           ierr = DMLabelSetValue(subpointMap, support[s], dim);CHKERRQ(ierr);
1191         }
1192       }
1193       ierr = DMPlexRestoreTransitiveClosure(dm, face, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
1194     }
1195     ierr = DMPlexRestoreTransitiveClosure(dm, vertex, PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
1196   }
1197   if (subvertexIS) {
1198     ierr = ISRestoreIndices(subvertexIS, &subvertices);CHKERRQ(ierr);
1199   }
1200   ierr = ISDestroy(&subvertexIS);CHKERRQ(ierr);
1201   ierr = PetscFree3(pStart,pEnd,pMax);CHKERRQ(ierr);
1202   PetscFunctionReturn(0);
1203 }
1204 
1205 #undef __FUNCT__
1206 #define __FUNCT__ "DMPlexGetFaceOrientation"
1207 PetscErrorCode DMPlexGetFaceOrientation(DM dm, PetscInt cell, PetscInt numCorners, PetscInt indices[], PetscInt oppositeVertex, PetscInt origVertices[], PetscInt faceVertices[], PetscBool *posOriented)
1208 {
1209   MPI_Comm       comm;
1210   PetscBool      posOrient = PETSC_FALSE;
1211   const PetscInt debug     = 0;
1212   PetscInt       cellDim, faceSize, f;
1213   PetscErrorCode ierr;
1214 
1215   PetscFunctionBegin;
1216   ierr = PetscObjectGetComm((PetscObject)dm,&comm);CHKERRQ(ierr);
1217   ierr = DMPlexGetDimension(dm, &cellDim);CHKERRQ(ierr);
1218   if (debug) {PetscPrintf(comm, "cellDim: %d numCorners: %d\n", cellDim, numCorners);CHKERRQ(ierr);}
1219 
1220   if (cellDim == numCorners-1) {
1221     /* Simplices */
1222     faceSize  = numCorners-1;
1223     posOrient = !(oppositeVertex%2) ? PETSC_TRUE : PETSC_FALSE;
1224   } else if (cellDim == 1 && numCorners == 3) {
1225     /* Quadratic line */
1226     faceSize  = 1;
1227     posOrient = PETSC_TRUE;
1228   } else if (cellDim == 2 && numCorners == 4) {
1229     /* Quads */
1230     faceSize = 2;
1231     if ((indices[1] > indices[0]) && (indices[1] - indices[0] == 1)) {
1232       posOrient = PETSC_TRUE;
1233     } else if ((indices[0] == 3) && (indices[1] == 0)) {
1234       posOrient = PETSC_TRUE;
1235     } else {
1236       if (((indices[0] > indices[1]) && (indices[0] - indices[1] == 1)) || ((indices[0] == 0) && (indices[1] == 3))) {
1237         posOrient = PETSC_FALSE;
1238       } else SETERRQ(comm, PETSC_ERR_ARG_WRONG, "Invalid quad crossedge");
1239     }
1240   } else if (cellDim == 2 && numCorners == 6) {
1241     /* Quadratic triangle (I hate this) */
1242     /* Edges are determined by the first 2 vertices (corners of edges) */
1243     const PetscInt faceSizeTri = 3;
1244     PetscInt       sortedIndices[3], i, iFace;
1245     PetscBool      found                    = PETSC_FALSE;
1246     PetscInt       faceVerticesTriSorted[9] = {
1247       0, 3,  4, /* bottom */
1248       1, 4,  5, /* right */
1249       2, 3,  5, /* left */
1250     };
1251     PetscInt       faceVerticesTri[9] = {
1252       0, 3,  4, /* bottom */
1253       1, 4,  5, /* right */
1254       2, 5,  3, /* left */
1255     };
1256 
1257     faceSize = faceSizeTri;
1258     for (i = 0; i < faceSizeTri; ++i) sortedIndices[i] = indices[i];
1259     ierr = PetscSortInt(faceSizeTri, sortedIndices);CHKERRQ(ierr);
1260     for (iFace = 0; iFace < 3; ++iFace) {
1261       const PetscInt ii = iFace*faceSizeTri;
1262       PetscInt       fVertex, cVertex;
1263 
1264       if ((sortedIndices[0] == faceVerticesTriSorted[ii+0]) &&
1265           (sortedIndices[1] == faceVerticesTriSorted[ii+1])) {
1266         for (fVertex = 0; fVertex < faceSizeTri; ++fVertex) {
1267           for (cVertex = 0; cVertex < faceSizeTri; ++cVertex) {
1268             if (indices[cVertex] == faceVerticesTri[ii+fVertex]) {
1269               faceVertices[fVertex] = origVertices[cVertex];
1270               break;
1271             }
1272           }
1273         }
1274         found = PETSC_TRUE;
1275         break;
1276       }
1277     }
1278     if (!found) SETERRQ(comm, PETSC_ERR_ARG_WRONG, "Invalid tri crossface");
1279     if (posOriented) *posOriented = PETSC_TRUE;
1280     PetscFunctionReturn(0);
1281   } else if (cellDim == 2 && numCorners == 9) {
1282     /* Quadratic quad (I hate this) */
1283     /* Edges are determined by the first 2 vertices (corners of edges) */
1284     const PetscInt faceSizeQuad = 3;
1285     PetscInt       sortedIndices[3], i, iFace;
1286     PetscBool      found                      = PETSC_FALSE;
1287     PetscInt       faceVerticesQuadSorted[12] = {
1288       0, 1,  4, /* bottom */
1289       1, 2,  5, /* right */
1290       2, 3,  6, /* top */
1291       0, 3,  7, /* left */
1292     };
1293     PetscInt       faceVerticesQuad[12] = {
1294       0, 1,  4, /* bottom */
1295       1, 2,  5, /* right */
1296       2, 3,  6, /* top */
1297       3, 0,  7, /* left */
1298     };
1299 
1300     faceSize = faceSizeQuad;
1301     for (i = 0; i < faceSizeQuad; ++i) sortedIndices[i] = indices[i];
1302     ierr = PetscSortInt(faceSizeQuad, sortedIndices);CHKERRQ(ierr);
1303     for (iFace = 0; iFace < 4; ++iFace) {
1304       const PetscInt ii = iFace*faceSizeQuad;
1305       PetscInt       fVertex, cVertex;
1306 
1307       if ((sortedIndices[0] == faceVerticesQuadSorted[ii+0]) &&
1308           (sortedIndices[1] == faceVerticesQuadSorted[ii+1])) {
1309         for (fVertex = 0; fVertex < faceSizeQuad; ++fVertex) {
1310           for (cVertex = 0; cVertex < faceSizeQuad; ++cVertex) {
1311             if (indices[cVertex] == faceVerticesQuad[ii+fVertex]) {
1312               faceVertices[fVertex] = origVertices[cVertex];
1313               break;
1314             }
1315           }
1316         }
1317         found = PETSC_TRUE;
1318         break;
1319       }
1320     }
1321     if (!found) SETERRQ(comm, PETSC_ERR_ARG_WRONG, "Invalid quad crossface");
1322     if (posOriented) *posOriented = PETSC_TRUE;
1323     PetscFunctionReturn(0);
1324   } else if (cellDim == 3 && numCorners == 8) {
1325     /* Hexes
1326        A hex is two oriented quads with the normal of the first
1327        pointing up at the second.
1328 
1329           7---6
1330          /|  /|
1331         4---5 |
1332         | 3-|-2
1333         |/  |/
1334         0---1
1335 
1336         Faces are determined by the first 4 vertices (corners of faces) */
1337     const PetscInt faceSizeHex = 4;
1338     PetscInt       sortedIndices[4], i, iFace;
1339     PetscBool      found                     = PETSC_FALSE;
1340     PetscInt       faceVerticesHexSorted[24] = {
1341       0, 1, 2, 3,  /* bottom */
1342       4, 5, 6, 7,  /* top */
1343       0, 1, 4, 5,  /* front */
1344       1, 2, 5, 6,  /* right */
1345       2, 3, 6, 7,  /* back */
1346       0, 3, 4, 7,  /* left */
1347     };
1348     PetscInt       faceVerticesHex[24] = {
1349       3, 2, 1, 0,  /* bottom */
1350       4, 5, 6, 7,  /* top */
1351       0, 1, 5, 4,  /* front */
1352       1, 2, 6, 5,  /* right */
1353       2, 3, 7, 6,  /* back */
1354       3, 0, 4, 7,  /* left */
1355     };
1356 
1357     faceSize = faceSizeHex;
1358     for (i = 0; i < faceSizeHex; ++i) sortedIndices[i] = indices[i];
1359     ierr = PetscSortInt(faceSizeHex, sortedIndices);CHKERRQ(ierr);
1360     for (iFace = 0; iFace < 6; ++iFace) {
1361       const PetscInt ii = iFace*faceSizeHex;
1362       PetscInt       fVertex, cVertex;
1363 
1364       if ((sortedIndices[0] == faceVerticesHexSorted[ii+0]) &&
1365           (sortedIndices[1] == faceVerticesHexSorted[ii+1]) &&
1366           (sortedIndices[2] == faceVerticesHexSorted[ii+2]) &&
1367           (sortedIndices[3] == faceVerticesHexSorted[ii+3])) {
1368         for (fVertex = 0; fVertex < faceSizeHex; ++fVertex) {
1369           for (cVertex = 0; cVertex < faceSizeHex; ++cVertex) {
1370             if (indices[cVertex] == faceVerticesHex[ii+fVertex]) {
1371               faceVertices[fVertex] = origVertices[cVertex];
1372               break;
1373             }
1374           }
1375         }
1376         found = PETSC_TRUE;
1377         break;
1378       }
1379     }
1380     if (!found) SETERRQ(comm, PETSC_ERR_ARG_WRONG, "Invalid hex crossface");
1381     if (posOriented) *posOriented = PETSC_TRUE;
1382     PetscFunctionReturn(0);
1383   } else if (cellDim == 3 && numCorners == 10) {
1384     /* Quadratic tet */
1385     /* Faces are determined by the first 3 vertices (corners of faces) */
1386     const PetscInt faceSizeTet = 6;
1387     PetscInt       sortedIndices[6], i, iFace;
1388     PetscBool      found                     = PETSC_FALSE;
1389     PetscInt       faceVerticesTetSorted[24] = {
1390       0, 1, 2,  6, 7, 8, /* bottom */
1391       0, 3, 4,  6, 7, 9,  /* front */
1392       1, 4, 5,  7, 8, 9,  /* right */
1393       2, 3, 5,  6, 8, 9,  /* left */
1394     };
1395     PetscInt       faceVerticesTet[24] = {
1396       0, 1, 2,  6, 7, 8, /* bottom */
1397       0, 4, 3,  6, 7, 9,  /* front */
1398       1, 5, 4,  7, 8, 9,  /* right */
1399       2, 3, 5,  8, 6, 9,  /* left */
1400     };
1401 
1402     faceSize = faceSizeTet;
1403     for (i = 0; i < faceSizeTet; ++i) sortedIndices[i] = indices[i];
1404     ierr = PetscSortInt(faceSizeTet, sortedIndices);CHKERRQ(ierr);
1405     for (iFace=0; iFace < 4; ++iFace) {
1406       const PetscInt ii = iFace*faceSizeTet;
1407       PetscInt       fVertex, cVertex;
1408 
1409       if ((sortedIndices[0] == faceVerticesTetSorted[ii+0]) &&
1410           (sortedIndices[1] == faceVerticesTetSorted[ii+1]) &&
1411           (sortedIndices[2] == faceVerticesTetSorted[ii+2]) &&
1412           (sortedIndices[3] == faceVerticesTetSorted[ii+3])) {
1413         for (fVertex = 0; fVertex < faceSizeTet; ++fVertex) {
1414           for (cVertex = 0; cVertex < faceSizeTet; ++cVertex) {
1415             if (indices[cVertex] == faceVerticesTet[ii+fVertex]) {
1416               faceVertices[fVertex] = origVertices[cVertex];
1417               break;
1418             }
1419           }
1420         }
1421         found = PETSC_TRUE;
1422         break;
1423       }
1424     }
1425     if (!found) SETERRQ(comm, PETSC_ERR_ARG_WRONG, "Invalid tet crossface");
1426     if (posOriented) *posOriented = PETSC_TRUE;
1427     PetscFunctionReturn(0);
1428   } else if (cellDim == 3 && numCorners == 27) {
1429     /* Quadratic hexes (I hate this)
1430        A hex is two oriented quads with the normal of the first
1431        pointing up at the second.
1432 
1433          7---6
1434         /|  /|
1435        4---5 |
1436        | 3-|-2
1437        |/  |/
1438        0---1
1439 
1440        Faces are determined by the first 4 vertices (corners of faces) */
1441     const PetscInt faceSizeQuadHex = 9;
1442     PetscInt       sortedIndices[9], i, iFace;
1443     PetscBool      found                         = PETSC_FALSE;
1444     PetscInt       faceVerticesQuadHexSorted[54] = {
1445       0, 1, 2, 3,  8, 9, 10, 11,  24, /* bottom */
1446       4, 5, 6, 7,  12, 13, 14, 15,  25, /* top */
1447       0, 1, 4, 5,  8, 12, 16, 17,  22, /* front */
1448       1, 2, 5, 6,  9, 13, 17, 18,  21, /* right */
1449       2, 3, 6, 7,  10, 14, 18, 19,  23, /* back */
1450       0, 3, 4, 7,  11, 15, 16, 19,  20, /* left */
1451     };
1452     PetscInt       faceVerticesQuadHex[54] = {
1453       3, 2, 1, 0,  10, 9, 8, 11,  24, /* bottom */
1454       4, 5, 6, 7,  12, 13, 14, 15,  25, /* top */
1455       0, 1, 5, 4,  8, 17, 12, 16,  22, /* front */
1456       1, 2, 6, 5,  9, 18, 13, 17,  21, /* right */
1457       2, 3, 7, 6,  10, 19, 14, 18,  23, /* back */
1458       3, 0, 4, 7,  11, 16, 15, 19,  20 /* left */
1459     };
1460 
1461     faceSize = faceSizeQuadHex;
1462     for (i = 0; i < faceSizeQuadHex; ++i) sortedIndices[i] = indices[i];
1463     ierr = PetscSortInt(faceSizeQuadHex, sortedIndices);CHKERRQ(ierr);
1464     for (iFace = 0; iFace < 6; ++iFace) {
1465       const PetscInt ii = iFace*faceSizeQuadHex;
1466       PetscInt       fVertex, cVertex;
1467 
1468       if ((sortedIndices[0] == faceVerticesQuadHexSorted[ii+0]) &&
1469           (sortedIndices[1] == faceVerticesQuadHexSorted[ii+1]) &&
1470           (sortedIndices[2] == faceVerticesQuadHexSorted[ii+2]) &&
1471           (sortedIndices[3] == faceVerticesQuadHexSorted[ii+3])) {
1472         for (fVertex = 0; fVertex < faceSizeQuadHex; ++fVertex) {
1473           for (cVertex = 0; cVertex < faceSizeQuadHex; ++cVertex) {
1474             if (indices[cVertex] == faceVerticesQuadHex[ii+fVertex]) {
1475               faceVertices[fVertex] = origVertices[cVertex];
1476               break;
1477             }
1478           }
1479         }
1480         found = PETSC_TRUE;
1481         break;
1482       }
1483     }
1484     if (!found) SETERRQ(comm, PETSC_ERR_ARG_WRONG, "Invalid hex crossface");
1485     if (posOriented) *posOriented = PETSC_TRUE;
1486     PetscFunctionReturn(0);
1487   } else SETERRQ(comm, PETSC_ERR_ARG_WRONG, "Unknown cell type for faceOrientation().");
1488   if (!posOrient) {
1489     if (debug) {ierr = PetscPrintf(comm, "  Reversing initial face orientation\n");CHKERRQ(ierr);}
1490     for (f = 0; f < faceSize; ++f) faceVertices[f] = origVertices[faceSize-1 - f];
1491   } else {
1492     if (debug) {ierr = PetscPrintf(comm, "  Keeping initial face orientation\n");CHKERRQ(ierr);}
1493     for (f = 0; f < faceSize; ++f) faceVertices[f] = origVertices[f];
1494   }
1495   if (posOriented) *posOriented = posOrient;
1496   PetscFunctionReturn(0);
1497 }
1498 
1499 #undef __FUNCT__
1500 #define __FUNCT__ "DMPlexGetOrientedFace"
1501 /*
1502     Given a cell and a face, as a set of vertices,
1503       return the oriented face, as a set of vertices, in faceVertices
1504     The orientation is such that the face normal points out of the cell
1505 */
1506 PetscErrorCode DMPlexGetOrientedFace(DM dm, PetscInt cell, PetscInt faceSize, const PetscInt face[], PetscInt numCorners, PetscInt indices[], PetscInt origVertices[], PetscInt faceVertices[], PetscBool *posOriented)
1507 {
1508   const PetscInt *cone = NULL;
1509   PetscInt        coneSize, v, f, v2;
1510   PetscInt        oppositeVertex = -1;
1511   PetscErrorCode  ierr;
1512 
1513   PetscFunctionBegin;
1514   ierr = DMPlexGetConeSize(dm, cell, &coneSize);CHKERRQ(ierr);
1515   ierr = DMPlexGetCone(dm, cell, &cone);CHKERRQ(ierr);
1516   for (v = 0, v2 = 0; v < coneSize; ++v) {
1517     PetscBool found = PETSC_FALSE;
1518 
1519     for (f = 0; f < faceSize; ++f) {
1520       if (face[f] == cone[v]) {
1521         found = PETSC_TRUE; break;
1522       }
1523     }
1524     if (found) {
1525       indices[v2]      = v;
1526       origVertices[v2] = cone[v];
1527       ++v2;
1528     } else {
1529       oppositeVertex = v;
1530     }
1531   }
1532   ierr = DMPlexGetFaceOrientation(dm, cell, numCorners, indices, oppositeVertex, origVertices, faceVertices, posOriented);CHKERRQ(ierr);
1533   PetscFunctionReturn(0);
1534 }
1535 
1536 #undef __FUNCT__
1537 #define __FUNCT__ "DMPlexInsertFace_Internal"
1538 /*
1539   DMPlexInsertFace_Internal - Puts a face into the mesh
1540 
1541   Not collective
1542 
1543   Input Parameters:
1544   + dm              - The DMPlex
1545   . numFaceVertex   - The number of vertices in the face
1546   . faceVertices    - The vertices in the face for dm
1547   . subfaceVertices - The vertices in the face for subdm
1548   . numCorners      - The number of vertices in the cell
1549   . cell            - A cell in dm containing the face
1550   . subcell         - A cell in subdm containing the face
1551   . firstFace       - First face in the mesh
1552   - newFacePoint    - Next face in the mesh
1553 
1554   Output Parameters:
1555   . newFacePoint - Contains next face point number on input, updated on output
1556 
1557   Level: developer
1558 */
1559 static PetscErrorCode DMPlexInsertFace_Internal(DM dm, DM subdm, PetscInt numFaceVertices, const PetscInt faceVertices[], const PetscInt subfaceVertices[], PetscInt numCorners, PetscInt cell, PetscInt subcell, PetscInt firstFace, PetscInt *newFacePoint)
1560 {
1561   MPI_Comm        comm;
1562   DM_Plex        *submesh = (DM_Plex*) subdm->data;
1563   const PetscInt *faces;
1564   PetscInt        numFaces, coneSize;
1565   PetscErrorCode  ierr;
1566 
1567   PetscFunctionBegin;
1568   ierr = PetscObjectGetComm((PetscObject)dm,&comm);CHKERRQ(ierr);
1569   ierr = DMPlexGetConeSize(subdm, subcell, &coneSize);CHKERRQ(ierr);
1570   if (coneSize != 1) SETERRQ2(comm, PETSC_ERR_ARG_OUTOFRANGE, "Cone size of cell %d is %d != 1", cell, coneSize);
1571 #if 0
1572   /* Cannot use this because support() has not been constructed yet */
1573   ierr = DMPlexGetJoin(subdm, numFaceVertices, subfaceVertices, &numFaces, &faces);CHKERRQ(ierr);
1574 #else
1575   {
1576     PetscInt f;
1577 
1578     numFaces = 0;
1579     ierr     = DMGetWorkArray(subdm, 1, PETSC_INT, (void**) &faces);CHKERRQ(ierr);
1580     for (f = firstFace; f < *newFacePoint; ++f) {
1581       PetscInt dof, off, d;
1582 
1583       ierr = PetscSectionGetDof(submesh->coneSection, f, &dof);CHKERRQ(ierr);
1584       ierr = PetscSectionGetOffset(submesh->coneSection, f, &off);CHKERRQ(ierr);
1585       /* Yes, I know this is quadratic, but I expect the sizes to be <5 */
1586       for (d = 0; d < dof; ++d) {
1587         const PetscInt p = submesh->cones[off+d];
1588         PetscInt       v;
1589 
1590         for (v = 0; v < numFaceVertices; ++v) {
1591           if (subfaceVertices[v] == p) break;
1592         }
1593         if (v == numFaceVertices) break;
1594       }
1595       if (d == dof) {
1596         numFaces               = 1;
1597         ((PetscInt*) faces)[0] = f;
1598       }
1599     }
1600   }
1601 #endif
1602   if (numFaces > 1) SETERRQ1(comm, PETSC_ERR_ARG_WRONG, "Vertex set had %d faces, not one", numFaces);
1603   else if (numFaces == 1) {
1604     /* Add the other cell neighbor for this face */
1605     ierr = DMPlexSetCone(subdm, cell, faces);CHKERRQ(ierr);
1606   } else {
1607     PetscInt *indices, *origVertices, *orientedVertices, *orientedSubVertices, v, ov;
1608     PetscBool posOriented;
1609 
1610     ierr                = DMGetWorkArray(subdm, 4*numFaceVertices * sizeof(PetscInt), PETSC_INT, &orientedVertices);CHKERRQ(ierr);
1611     origVertices        = &orientedVertices[numFaceVertices];
1612     indices             = &orientedVertices[numFaceVertices*2];
1613     orientedSubVertices = &orientedVertices[numFaceVertices*3];
1614     ierr                = DMPlexGetOrientedFace(dm, cell, numFaceVertices, faceVertices, numCorners, indices, origVertices, orientedVertices, &posOriented);CHKERRQ(ierr);
1615     /* TODO: I know that routine should return a permutation, not the indices */
1616     for (v = 0; v < numFaceVertices; ++v) {
1617       const PetscInt vertex = faceVertices[v], subvertex = subfaceVertices[v];
1618       for (ov = 0; ov < numFaceVertices; ++ov) {
1619         if (orientedVertices[ov] == vertex) {
1620           orientedSubVertices[ov] = subvertex;
1621           break;
1622         }
1623       }
1624       if (ov == numFaceVertices) SETERRQ1(comm, PETSC_ERR_PLIB, "Could not find face vertex %d in orientated set", vertex);
1625     }
1626     ierr = DMPlexSetCone(subdm, *newFacePoint, orientedSubVertices);CHKERRQ(ierr);
1627     ierr = DMPlexSetCone(subdm, subcell, newFacePoint);CHKERRQ(ierr);
1628     ierr = DMRestoreWorkArray(subdm, 4*numFaceVertices * sizeof(PetscInt), PETSC_INT, &orientedVertices);CHKERRQ(ierr);
1629     ++(*newFacePoint);
1630   }
1631   ierr = DMPlexRestoreJoin(subdm, numFaceVertices, subfaceVertices, &numFaces, &faces);CHKERRQ(ierr);
1632   PetscFunctionReturn(0);
1633 }
1634 
1635 #undef __FUNCT__
1636 #define __FUNCT__ "DMPlexCreateSubmesh_Uninterpolated"
1637 static PetscErrorCode DMPlexCreateSubmesh_Uninterpolated(DM dm, const char vertexLabelName[], DM subdm)
1638 {
1639   MPI_Comm        comm;
1640   DMLabel         vertexLabel, subpointMap;
1641   IS              subvertexIS,  subcellIS;
1642   const PetscInt *subVertices, *subCells;
1643   PetscInt        numSubVertices, firstSubVertex, numSubCells;
1644   PetscInt       *subface, maxConeSize, numSubFaces, firstSubFace, newFacePoint, nFV;
1645   PetscInt        vStart, vEnd, c, f;
1646   PetscErrorCode  ierr;
1647 
1648   PetscFunctionBegin;
1649   ierr = PetscObjectGetComm((PetscObject)dm,&comm);CHKERRQ(ierr);
1650   /* Create subpointMap which marks the submesh */
1651   ierr = DMLabelCreate("subpoint_map", &subpointMap);CHKERRQ(ierr);
1652   ierr = DMPlexSetSubpointMap(subdm, subpointMap);CHKERRQ(ierr);
1653   ierr = DMLabelDestroy(&subpointMap);CHKERRQ(ierr);
1654   ierr = DMPlexGetLabel(dm, vertexLabelName, &vertexLabel);CHKERRQ(ierr);
1655   ierr = DMPlexMarkSubmesh_Uninterpolated(dm, vertexLabel, subpointMap, &numSubFaces, &nFV, subdm);CHKERRQ(ierr);
1656   /* Setup chart */
1657   ierr = DMLabelGetStratumSize(subpointMap, 0, &numSubVertices);CHKERRQ(ierr);
1658   ierr = DMLabelGetStratumSize(subpointMap, 2, &numSubCells);CHKERRQ(ierr);
1659   ierr = DMPlexSetChart(subdm, 0, numSubCells+numSubFaces+numSubVertices);CHKERRQ(ierr);
1660   ierr = DMPlexSetVTKCellHeight(subdm, 1);CHKERRQ(ierr);
1661   /* Set cone sizes */
1662   firstSubVertex = numSubCells;
1663   firstSubFace   = numSubCells+numSubVertices;
1664   newFacePoint   = firstSubFace;
1665   ierr = DMLabelGetStratumIS(subpointMap, 0, &subvertexIS);CHKERRQ(ierr);
1666   if (subvertexIS) {ierr = ISGetIndices(subvertexIS, &subVertices);CHKERRQ(ierr);}
1667   ierr = DMLabelGetStratumIS(subpointMap, 2, &subcellIS);CHKERRQ(ierr);
1668   if (subcellIS) {ierr = ISGetIndices(subcellIS, &subCells);CHKERRQ(ierr);}
1669   for (c = 0; c < numSubCells; ++c) {
1670     ierr = DMPlexSetConeSize(subdm, c, 1);CHKERRQ(ierr);
1671   }
1672   for (f = firstSubFace; f < firstSubFace+numSubFaces; ++f) {
1673     ierr = DMPlexSetConeSize(subdm, f, nFV);CHKERRQ(ierr);
1674   }
1675   ierr = DMSetUp(subdm);CHKERRQ(ierr);
1676   /* Create face cones */
1677   ierr = DMPlexGetDepthStratum(dm, 0, &vStart, &vEnd);CHKERRQ(ierr);
1678   ierr = DMPlexGetMaxSizes(dm, &maxConeSize, NULL);CHKERRQ(ierr);
1679   ierr = DMGetWorkArray(subdm, maxConeSize, PETSC_INT, (void**) &subface);CHKERRQ(ierr);
1680   for (c = 0; c < numSubCells; ++c) {
1681     const PetscInt cell    = subCells[c];
1682     const PetscInt subcell = c;
1683     PetscInt      *closure = NULL;
1684     PetscInt       closureSize, cl, numCorners = 0, faceSize = 0;
1685 
1686     ierr = DMPlexGetTransitiveClosure(dm, cell, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
1687     for (cl = 0; cl < closureSize*2; cl += 2) {
1688       const PetscInt point = closure[cl];
1689       PetscInt       subVertex;
1690 
1691       if ((point >= vStart) && (point < vEnd)) {
1692         ++numCorners;
1693         ierr = PetscFindInt(point, numSubVertices, subVertices, &subVertex);CHKERRQ(ierr);
1694         if (subVertex >= 0) {
1695           closure[faceSize] = point;
1696           subface[faceSize] = firstSubVertex+subVertex;
1697           ++faceSize;
1698         }
1699       }
1700     }
1701     if (faceSize > nFV) SETERRQ1(comm, PETSC_ERR_ARG_WRONG, "Invalid submesh: Too many vertices %d of an element on the surface", faceSize);
1702     if (faceSize == nFV) {
1703       ierr = DMPlexInsertFace_Internal(dm, subdm, faceSize, closure, subface, numCorners, cell, subcell, firstSubFace, &newFacePoint);CHKERRQ(ierr);
1704     }
1705     ierr = DMPlexRestoreTransitiveClosure(dm, cell, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
1706   }
1707   ierr = DMRestoreWorkArray(subdm, maxConeSize, PETSC_INT, (void**) &subface);CHKERRQ(ierr);
1708   ierr = DMPlexSymmetrize(subdm);CHKERRQ(ierr);
1709   ierr = DMPlexStratify(subdm);CHKERRQ(ierr);
1710   /* Build coordinates */
1711   {
1712     PetscSection coordSection, subCoordSection;
1713     Vec          coordinates, subCoordinates;
1714     PetscScalar *coords, *subCoords;
1715     PetscInt     coordSize, v;
1716 
1717     ierr = DMPlexGetCoordinateSection(dm, &coordSection);CHKERRQ(ierr);
1718     ierr = DMGetCoordinatesLocal(dm, &coordinates);CHKERRQ(ierr);
1719     ierr = DMPlexGetCoordinateSection(subdm, &subCoordSection);CHKERRQ(ierr);
1720     ierr = PetscSectionSetChart(subCoordSection, firstSubVertex, firstSubVertex+numSubVertices);CHKERRQ(ierr);
1721     for (v = 0; v < numSubVertices; ++v) {
1722       const PetscInt vertex    = subVertices[v];
1723       const PetscInt subvertex = firstSubVertex+v;
1724       PetscInt       dof;
1725 
1726       ierr = PetscSectionGetDof(coordSection, vertex, &dof);CHKERRQ(ierr);
1727       ierr = PetscSectionSetDof(subCoordSection, subvertex, dof);CHKERRQ(ierr);
1728     }
1729     ierr = PetscSectionSetUp(subCoordSection);CHKERRQ(ierr);
1730     ierr = PetscSectionGetStorageSize(subCoordSection, &coordSize);CHKERRQ(ierr);
1731     ierr = VecCreate(comm, &subCoordinates);CHKERRQ(ierr);
1732     ierr = VecSetSizes(subCoordinates, coordSize, PETSC_DETERMINE);CHKERRQ(ierr);
1733     ierr = VecSetFromOptions(subCoordinates);CHKERRQ(ierr);
1734     ierr = VecGetArray(coordinates,    &coords);CHKERRQ(ierr);
1735     ierr = VecGetArray(subCoordinates, &subCoords);CHKERRQ(ierr);
1736     for (v = 0; v < numSubVertices; ++v) {
1737       const PetscInt vertex    = subVertices[v];
1738       const PetscInt subvertex = firstSubVertex+v;
1739       PetscInt       dof, off, sdof, soff, d;
1740 
1741       ierr = PetscSectionGetDof(coordSection, vertex, &dof);CHKERRQ(ierr);
1742       ierr = PetscSectionGetOffset(coordSection, vertex, &off);CHKERRQ(ierr);
1743       ierr = PetscSectionGetDof(subCoordSection, subvertex, &sdof);CHKERRQ(ierr);
1744       ierr = PetscSectionGetOffset(subCoordSection, subvertex, &soff);CHKERRQ(ierr);
1745       if (dof != sdof) SETERRQ4(comm, PETSC_ERR_PLIB, "Coordinate dimension %d on subvertex %d, vertex %d should be %d", sdof, subvertex, vertex, dof);
1746       for (d = 0; d < dof; ++d) subCoords[soff+d] = coords[off+d];
1747     }
1748     ierr = VecRestoreArray(coordinates,    &coords);CHKERRQ(ierr);
1749     ierr = VecRestoreArray(subCoordinates, &subCoords);CHKERRQ(ierr);
1750     ierr = DMSetCoordinatesLocal(subdm, subCoordinates);CHKERRQ(ierr);
1751     ierr = VecDestroy(&subCoordinates);CHKERRQ(ierr);
1752   }
1753   /* Cleanup */
1754   if (subvertexIS) {ierr = ISRestoreIndices(subvertexIS, &subVertices);CHKERRQ(ierr);}
1755   ierr = ISDestroy(&subvertexIS);CHKERRQ(ierr);
1756   if (subcellIS) {ierr = ISRestoreIndices(subcellIS, &subCells);CHKERRQ(ierr);}
1757   ierr = ISDestroy(&subcellIS);CHKERRQ(ierr);
1758   PetscFunctionReturn(0);
1759 }
1760 
1761 #undef __FUNCT__
1762 #define __FUNCT__ "DMPlexCreateSubmesh_Interpolated"
1763 static PetscErrorCode DMPlexCreateSubmesh_Interpolated(DM dm, const char vertexLabelName[], DM subdm)
1764 {
1765   MPI_Comm         comm;
1766   DMLabel          subpointMap, vertexLabel;
1767   IS              *subpointIS;
1768   const PetscInt **subpoints;
1769   PetscInt        *numSubPoints, *firstSubPoint, *coneNew;
1770   PetscInt         totSubPoints = 0, maxConeSize, dim, p, d, v;
1771   PetscErrorCode   ierr;
1772 
1773   PetscFunctionBegin;
1774   ierr = PetscObjectGetComm((PetscObject)dm,&comm);CHKERRQ(ierr);
1775   /* Create subpointMap which marks the submesh */
1776   ierr = DMLabelCreate("subpoint_map", &subpointMap);CHKERRQ(ierr);
1777   ierr = DMPlexSetSubpointMap(subdm, subpointMap);CHKERRQ(ierr);
1778   ierr = DMLabelDestroy(&subpointMap);CHKERRQ(ierr);
1779   ierr = DMPlexGetLabel(dm, vertexLabelName, &vertexLabel);CHKERRQ(ierr);
1780   ierr = DMPlexMarkSubmesh_Interpolated(dm, vertexLabel, subpointMap, subdm);CHKERRQ(ierr);
1781   /* Setup chart */
1782   ierr = DMPlexGetDimension(dm, &dim);CHKERRQ(ierr);
1783   ierr = PetscMalloc4(dim+1,PetscInt,&numSubPoints,dim+1,PetscInt,&firstSubPoint,dim+1,IS,&subpointIS,dim+1,const PetscInt *,&subpoints);CHKERRQ(ierr);
1784   for (d = 0; d <= dim; ++d) {
1785     ierr = DMLabelGetStratumSize(subpointMap, d, &numSubPoints[d]);CHKERRQ(ierr);
1786     totSubPoints += numSubPoints[d];
1787   }
1788   ierr = DMPlexSetChart(subdm, 0, totSubPoints);CHKERRQ(ierr);
1789   ierr = DMPlexSetVTKCellHeight(subdm, 1);CHKERRQ(ierr);
1790   /* Set cone sizes */
1791   firstSubPoint[dim] = 0;
1792   firstSubPoint[0]   = firstSubPoint[dim] + numSubPoints[dim];
1793   if (dim > 1) {firstSubPoint[dim-1] = firstSubPoint[0]     + numSubPoints[0];}
1794   if (dim > 2) {firstSubPoint[dim-2] = firstSubPoint[dim-1] + numSubPoints[dim-1];}
1795   for (d = 0; d <= dim; ++d) {
1796     ierr = DMLabelGetStratumIS(subpointMap, d, &subpointIS[d]);CHKERRQ(ierr);
1797     ierr = ISGetIndices(subpointIS[d], &subpoints[d]);CHKERRQ(ierr);
1798   }
1799   for (d = 0; d <= dim; ++d) {
1800     for (p = 0; p < numSubPoints[d]; ++p) {
1801       const PetscInt  point    = subpoints[d][p];
1802       const PetscInt  subpoint = firstSubPoint[d] + p;
1803       const PetscInt *cone;
1804       PetscInt        coneSize, coneSizeNew, c, val;
1805 
1806       ierr = DMPlexGetConeSize(dm, point, &coneSize);CHKERRQ(ierr);
1807       ierr = DMPlexSetConeSize(subdm, subpoint, coneSize);CHKERRQ(ierr);
1808       if (d == dim) {
1809         ierr = DMPlexGetCone(dm, point, &cone);CHKERRQ(ierr);
1810         for (c = 0, coneSizeNew = 0; c < coneSize; ++c) {
1811           ierr = DMLabelGetValue(subpointMap, cone[c], &val);CHKERRQ(ierr);
1812           if (val >= 0) coneSizeNew++;
1813         }
1814         ierr = DMPlexSetConeSize(subdm, subpoint, coneSizeNew);CHKERRQ(ierr);
1815       }
1816     }
1817   }
1818   ierr = DMSetUp(subdm);CHKERRQ(ierr);
1819   /* Set cones */
1820   ierr = DMPlexGetMaxSizes(dm, &maxConeSize, NULL);CHKERRQ(ierr);
1821   ierr = PetscMalloc(maxConeSize * sizeof(PetscInt), &coneNew);CHKERRQ(ierr);
1822   for (d = 0; d <= dim; ++d) {
1823     for (p = 0; p < numSubPoints[d]; ++p) {
1824       const PetscInt  point    = subpoints[d][p];
1825       const PetscInt  subpoint = firstSubPoint[d] + p;
1826       const PetscInt *cone;
1827       PetscInt        coneSize, subconeSize, coneSizeNew, c, subc;
1828 
1829       ierr = DMPlexGetConeSize(dm, point, &coneSize);CHKERRQ(ierr);
1830       ierr = DMPlexGetConeSize(subdm, subpoint, &subconeSize);CHKERRQ(ierr);
1831       ierr = DMPlexGetCone(dm, point, &cone);CHKERRQ(ierr);
1832       for (c = 0, coneSizeNew = 0; c < coneSize; ++c) {
1833         ierr = PetscFindInt(cone[c], numSubPoints[d-1], subpoints[d-1], &subc);CHKERRQ(ierr);
1834         if (subc >= 0) coneNew[coneSizeNew++] = firstSubPoint[d-1] + subc;
1835       }
1836       if (coneSizeNew != subconeSize) SETERRQ2(comm, PETSC_ERR_PLIB, "Number of cone points located %d does not match subcone size %d", coneSizeNew, subconeSize);
1837       ierr = DMPlexSetCone(subdm, subpoint, coneNew);CHKERRQ(ierr);
1838     }
1839   }
1840   ierr = PetscFree(coneNew);CHKERRQ(ierr);
1841   ierr = DMPlexSymmetrize(subdm);CHKERRQ(ierr);
1842   ierr = DMPlexStratify(subdm);CHKERRQ(ierr);
1843   /* Build coordinates */
1844   {
1845     PetscSection coordSection, subCoordSection;
1846     Vec          coordinates, subCoordinates;
1847     PetscScalar *coords, *subCoords;
1848     PetscInt     coordSize;
1849 
1850     ierr = DMPlexGetCoordinateSection(dm, &coordSection);CHKERRQ(ierr);
1851     ierr = DMGetCoordinatesLocal(dm, &coordinates);CHKERRQ(ierr);
1852     ierr = DMPlexGetCoordinateSection(subdm, &subCoordSection);CHKERRQ(ierr);
1853     ierr = PetscSectionSetChart(subCoordSection, firstSubPoint[0], firstSubPoint[0]+numSubPoints[0]);CHKERRQ(ierr);
1854     for (v = 0; v < numSubPoints[0]; ++v) {
1855       const PetscInt vertex    = subpoints[0][v];
1856       const PetscInt subvertex = firstSubPoint[0]+v;
1857       PetscInt       dof;
1858 
1859       ierr = PetscSectionGetDof(coordSection, vertex, &dof);CHKERRQ(ierr);
1860       ierr = PetscSectionSetDof(subCoordSection, subvertex, dof);CHKERRQ(ierr);
1861     }
1862     ierr = PetscSectionSetUp(subCoordSection);CHKERRQ(ierr);
1863     ierr = PetscSectionGetStorageSize(subCoordSection, &coordSize);CHKERRQ(ierr);
1864     ierr = VecCreate(comm, &subCoordinates);CHKERRQ(ierr);
1865     ierr = VecSetSizes(subCoordinates, coordSize, PETSC_DETERMINE);CHKERRQ(ierr);
1866     ierr = VecSetFromOptions(subCoordinates);CHKERRQ(ierr);
1867     ierr = VecGetArray(coordinates,    &coords);CHKERRQ(ierr);
1868     ierr = VecGetArray(subCoordinates, &subCoords);CHKERRQ(ierr);
1869     for (v = 0; v < numSubPoints[0]; ++v) {
1870       const PetscInt vertex    = subpoints[0][v];
1871       const PetscInt subvertex = firstSubPoint[0]+v;
1872       PetscInt dof, off, sdof, soff, d;
1873 
1874       ierr = PetscSectionGetDof(coordSection, vertex, &dof);CHKERRQ(ierr);
1875       ierr = PetscSectionGetOffset(coordSection, vertex, &off);CHKERRQ(ierr);
1876       ierr = PetscSectionGetDof(subCoordSection, subvertex, &sdof);CHKERRQ(ierr);
1877       ierr = PetscSectionGetOffset(subCoordSection, subvertex, &soff);CHKERRQ(ierr);
1878       if (dof != sdof) SETERRQ4(comm, PETSC_ERR_PLIB, "Coordinate dimension %d on subvertex %d, vertex %d should be %d", sdof, subvertex, vertex, dof);
1879       for (d = 0; d < dof; ++d) subCoords[soff+d] = coords[off+d];
1880     }
1881     ierr = VecRestoreArray(coordinates,    &coords);CHKERRQ(ierr);
1882     ierr = VecRestoreArray(subCoordinates, &subCoords);CHKERRQ(ierr);
1883     ierr = DMSetCoordinatesLocal(subdm, subCoordinates);CHKERRQ(ierr);
1884     ierr = VecDestroy(&subCoordinates);CHKERRQ(ierr);
1885   }
1886   /* Cleanup */
1887   for (d = 0; d <= dim; ++d) {
1888     ierr = ISRestoreIndices(subpointIS[d], &subpoints[d]);CHKERRQ(ierr);
1889     ierr = ISDestroy(&subpointIS[d]);CHKERRQ(ierr);
1890   }
1891   ierr = PetscFree4(numSubPoints,firstSubPoint,subpointIS,subpoints);CHKERRQ(ierr);
1892   PetscFunctionReturn(0);
1893 }
1894 
1895 #undef __FUNCT__
1896 #define __FUNCT__ "DMPlexCreateSubmesh"
1897 /*
1898   DMPlexCreateSubmesh - Extract a hypersurface from the mesh using vertices defined by a label
1899 
1900   Input Parameters:
1901 + dm           - The original mesh
1902 - vertexLabel  - The DMLabel marking vertices contained in the surface
1903 
1904   Output Parameter:
1905 . subdm - The surface mesh
1906 
1907   Note: This function produces a DMLabel mapping original points in the submesh to their depth. This can be obtained using DMPlexGetSubpointMap().
1908 
1909   Level: developer
1910 
1911 .seealso: DMPlexGetSubpointMap(), DMPlexGetLabel(), DMLabelSetValue()
1912 */
1913 PetscErrorCode DMPlexCreateSubmesh(DM dm, const char vertexLabel[], DM *subdm)
1914 {
1915   PetscInt       dim, depth;
1916   PetscErrorCode ierr;
1917 
1918   PetscFunctionBegin;
1919   PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
1920   PetscValidCharPointer(vertexLabel, 2);
1921   PetscValidPointer(subdm, 4);
1922   ierr = DMPlexGetDimension(dm, &dim);CHKERRQ(ierr);
1923   ierr = DMPlexGetDepth(dm, &depth);CHKERRQ(ierr);
1924   ierr = DMCreate(PetscObjectComm((PetscObject)dm), subdm);CHKERRQ(ierr);
1925   ierr = DMSetType(*subdm, DMPLEX);CHKERRQ(ierr);
1926   ierr = DMPlexSetDimension(*subdm, dim-1);CHKERRQ(ierr);
1927   if (depth == dim) {
1928     ierr = DMPlexCreateSubmesh_Interpolated(dm, vertexLabel, *subdm);CHKERRQ(ierr);
1929   } else {
1930     ierr = DMPlexCreateSubmesh_Uninterpolated(dm, vertexLabel, *subdm);CHKERRQ(ierr);
1931   }
1932   PetscFunctionReturn(0);
1933 }
1934 
1935 #undef __FUNCT__
1936 #define __FUNCT__ "DMPlexGetSubpointMap"
1937 PetscErrorCode DMPlexGetSubpointMap(DM dm, DMLabel *subpointMap)
1938 {
1939   DM_Plex *mesh = (DM_Plex*) dm->data;
1940 
1941   PetscFunctionBegin;
1942   PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
1943   PetscValidPointer(subpointMap, 2);
1944   *subpointMap = mesh->subpointMap;
1945   PetscFunctionReturn(0);
1946 }
1947 
1948 #undef __FUNCT__
1949 #define __FUNCT__ "DMPlexSetSubpointMap"
1950 /* Note: Should normally not be called by the user, since it is set in DMPlexCreateSubmesh() */
1951 PetscErrorCode DMPlexSetSubpointMap(DM dm, DMLabel subpointMap)
1952 {
1953   DM_Plex       *mesh = (DM_Plex *) dm->data;
1954   PetscErrorCode ierr;
1955 
1956   PetscFunctionBegin;
1957   PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
1958   ierr = DMLabelDestroy(&mesh->subpointMap);CHKERRQ(ierr);
1959   mesh->subpointMap = subpointMap;
1960   ++mesh->subpointMap->refct;CHKERRQ(ierr);
1961   PetscFunctionReturn(0);
1962 }
1963 
1964 #undef __FUNCT__
1965 #define __FUNCT__ "DMPlexCreateSubpointIS"
1966 /*
1967   DMPlexCreateSubpointIS - Creates an IS covering the entire subdm chart with the original points as data
1968 
1969   Input Parameter:
1970 . dm - The submesh DM
1971 
1972   Output Parameter:
1973 . subpointIS - The IS of all the points from the original mesh in this submesh, or NULL if this is not a submesh
1974 
1975   Note: This is IS is guaranteed to be sorted by the construction of the submesh
1976 */
1977 PetscErrorCode DMPlexCreateSubpointIS(DM dm, IS *subpointIS)
1978 {
1979   MPI_Comm        comm;
1980   DMLabel         subpointMap;
1981   IS              is;
1982   const PetscInt *opoints;
1983   PetscInt       *points, *depths;
1984   PetscInt        depth, depStart, depEnd, d, pStart, pEnd, p, n, off;
1985   PetscErrorCode  ierr;
1986 
1987   PetscFunctionBegin;
1988   PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
1989   PetscValidPointer(subpointIS, 2);
1990   ierr = PetscObjectGetComm((PetscObject)dm,&comm);CHKERRQ(ierr);
1991   *subpointIS = NULL;
1992   ierr = DMPlexGetSubpointMap(dm, &subpointMap);CHKERRQ(ierr);
1993   if (subpointMap) {
1994     ierr = DMPlexGetDepth(dm, &depth);CHKERRQ(ierr);
1995     ierr = DMPlexGetChart(dm, &pStart, &pEnd);CHKERRQ(ierr);
1996     if (pStart) SETERRQ1(comm, PETSC_ERR_ARG_WRONG, "Submeshes must start the point numbering at 0, not %d", pStart);
1997     ierr = DMGetWorkArray(dm, depth+1, PETSC_INT, &depths);CHKERRQ(ierr);
1998     depths[0] = depth;
1999     depths[1] = 0;
2000     for(d = 2; d <= depth; ++d) {depths[d] = depth+1 - d;}
2001     ierr = PetscMalloc(pEnd * sizeof(PetscInt), &points);CHKERRQ(ierr);
2002     for(d = 0, off = 0; d <= depth; ++d) {
2003       const PetscInt dep = depths[d];
2004 
2005       ierr = DMPlexGetDepthStratum(dm, dep, &depStart, &depEnd);CHKERRQ(ierr);
2006       ierr = DMLabelGetStratumSize(subpointMap, dep, &n);CHKERRQ(ierr);
2007       if (((d < 2) && (depth > 1)) || (d == 1)) { /* Only check vertices and cells for now since the map is broken for others */
2008         if (n != depEnd-depStart) SETERRQ3(comm, PETSC_ERR_ARG_WRONG, "The number of mapped submesh points %d at depth %d should be %d", n, dep, depEnd-depStart);
2009       } else {
2010         if (!n) {
2011           if (d == 0) {
2012             /* Missing cells */
2013             for(p = 0; p < depEnd-depStart; ++p, ++off) points[off] = -1;
2014           } else {
2015             /* Missing faces */
2016             for(p = 0; p < depEnd-depStart; ++p, ++off) points[off] = PETSC_MAX_INT;
2017           }
2018         }
2019       }
2020       if (n) {
2021         ierr = DMLabelGetStratumIS(subpointMap, dep, &is);CHKERRQ(ierr);
2022         ierr = ISGetIndices(is, &opoints);CHKERRQ(ierr);
2023         for(p = 0; p < n; ++p, ++off) points[off] = opoints[p];
2024         ierr = ISRestoreIndices(is, &opoints);CHKERRQ(ierr);
2025         ierr = ISDestroy(&is);CHKERRQ(ierr);
2026       }
2027     }
2028     ierr = DMRestoreWorkArray(dm, depth+1, PETSC_INT, &depths);CHKERRQ(ierr);
2029     if (off != pEnd) SETERRQ2(comm, PETSC_ERR_ARG_WRONG, "The number of mapped submesh points %d should be %d", off, pEnd);
2030     ierr = ISCreateGeneral(comm, pEnd, points, PETSC_OWN_POINTER, subpointIS);CHKERRQ(ierr);
2031   }
2032   PetscFunctionReturn(0);
2033 }
2034