xref: /petsc/src/ksp/pc/impls/patch/pcpatch.c (revision 99b7e5c6b0d3a6fe33f8cf4f423642276681f226)
1 #include <petsc/private/pcpatchimpl.h>     /*I "petscpc.h" I*/
2 #include <petsc/private/kspimpl.h>         /* For ksp->setfromoptionscalled */
3 #include <petsc/private/dmpleximpl.h> /* For DMPlexComputeJacobian_Patch_Internal() */
4 #include <petscsf.h>
5 #include <petscbt.h>
6 #include <petscds.h>
7 
8 PetscLogEvent PC_Patch_CreatePatches, PC_Patch_ComputeOp, PC_Patch_Solve, PC_Patch_Scatter, PC_Patch_Apply, PC_Patch_Prealloc;
9 
10 PETSC_STATIC_INLINE PetscErrorCode ObjectView(PetscObject obj, PetscViewer viewer, PetscViewerFormat format)
11 {
12   PetscErrorCode ierr;
13 
14   ierr = PetscViewerPushFormat(viewer, format);CHKERRQ(ierr);
15   ierr = PetscObjectView(obj, viewer);CHKERRQ(ierr);
16   ierr = PetscViewerPopFormat(viewer);CHKERRQ(ierr);
17   return(0);
18 }
19 
20 static PetscErrorCode PCPatchConstruct_Star(void *vpatch, DM dm, PetscInt point, PetscHSetI ht)
21 {
22   PetscInt       starSize;
23   PetscInt      *star = NULL, si;
24   PetscErrorCode ierr;
25 
26   PetscFunctionBegin;
27   PetscHSetIClear(ht);
28   /* To start with, add the point we care about */
29   ierr = PetscHSetIAdd(ht, point);CHKERRQ(ierr);
30   /* Loop over all the points that this point connects to */
31   ierr = DMPlexGetTransitiveClosure(dm, point, PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
32   for (si = 0; si < starSize*2; si += 2) {ierr = PetscHSetIAdd(ht, star[si]);CHKERRQ(ierr);}
33   ierr = DMPlexRestoreTransitiveClosure(dm, point, PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
34   PetscFunctionReturn(0);
35 }
36 
37 static PetscErrorCode PCPatchConstruct_Vanka(void *vpatch, DM dm, PetscInt point, PetscHSetI ht)
38 {
39   PC_PATCH      *patch = (PC_PATCH *) vpatch;
40   PetscInt       starSize;
41   PetscInt      *star = NULL;
42   PetscBool      shouldIgnore = PETSC_FALSE;
43   PetscInt       cStart, cEnd, iStart, iEnd, si;
44   PetscErrorCode ierr;
45 
46   PetscFunctionBegin;
47   ierr = PetscHSetIClear(ht);CHKERRQ(ierr);
48   /* To start with, add the point we care about */
49   ierr = PetscHSetIAdd(ht, point);CHKERRQ(ierr);
50   /* Should we ignore any points of a certain dimension? */
51   if (patch->vankadim >= 0) {
52     shouldIgnore = PETSC_TRUE;
53     ierr = DMPlexGetDepthStratum(dm, patch->vankadim, &iStart, &iEnd);CHKERRQ(ierr);
54   }
55   ierr = DMPlexGetHeightStratum(dm, 0, &cStart, &cEnd);CHKERRQ(ierr);
56   /* Loop over all the cells that this point connects to */
57   ierr = DMPlexGetTransitiveClosure(dm, point, PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
58   for (si = 0; si < starSize*2; si += 2) {
59     const PetscInt cell = star[si];
60     PetscInt       closureSize;
61     PetscInt      *closure = NULL, ci;
62 
63     if (cell < cStart || cell >= cEnd) continue;
64     /* now loop over all entities in the closure of that cell */
65     ierr = DMPlexGetTransitiveClosure(dm, cell, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
66     for (ci = 0; ci < closureSize*2; ci += 2) {
67       const PetscInt newpoint = closure[ci];
68 
69       /* We've been told to ignore entities of this type.*/
70       if (shouldIgnore && newpoint >= iStart && newpoint < iEnd) continue;
71       ierr = PetscHSetIAdd(ht, newpoint);CHKERRQ(ierr);
72     }
73     ierr = DMPlexRestoreTransitiveClosure(dm, cell, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
74   }
75   ierr = DMPlexRestoreTransitiveClosure(dm, point, PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
76   PetscFunctionReturn(0);
77 }
78 
79 static PetscErrorCode PCPatchConstruct_Pardecomp(void *vpatch, DM dm, PetscInt point, PetscHSetI ht)
80 {
81   PC_PATCH       *patch = (PC_PATCH *) vpatch;
82   DMLabel         ghost = NULL;
83   const PetscInt *leaves;
84   PetscInt        nleaves, pStart, pEnd, loc;
85   PetscBool       isFiredrake;
86   DM              plex;
87   PetscBool       flg;
88   PetscInt        starSize;
89   PetscInt       *star = NULL;
90   PetscInt        opoint, overlapi;
91   PetscErrorCode  ierr;
92 
93   PetscFunctionBegin;
94   PetscHSetIClear(ht);
95 
96   ierr = DMConvert(dm, DMPLEX, &plex);CHKERRQ(ierr);
97   ierr = DMPlexGetChart(plex, &pStart, &pEnd);CHKERRQ(ierr);
98 
99   ierr = DMHasLabel(dm, "pyop2_ghost", &isFiredrake);CHKERRQ(ierr);
100   if (isFiredrake) {
101     ierr = DMGetLabel(dm, "pyop2_ghost", &ghost);CHKERRQ(ierr);
102     ierr = DMLabelCreateIndex(ghost, pStart, pEnd);CHKERRQ(ierr);
103   } else {
104     PetscSF sf;
105     ierr = DMGetPointSF(dm, &sf);CHKERRQ(ierr);
106     ierr = PetscSFGetGraph(sf, NULL, &nleaves, &leaves, NULL);CHKERRQ(ierr);
107     nleaves = PetscMax(nleaves, 0);
108   }
109 
110   for (opoint = pStart; opoint < pEnd; ++opoint) {
111     if (ghost) {ierr = DMLabelHasPoint(ghost, opoint, &flg);CHKERRQ(ierr);}
112     else       {ierr = PetscFindInt(opoint, nleaves, leaves, &loc);CHKERRQ(ierr); flg = loc >=0 ? PETSC_TRUE : PETSC_FALSE;}
113     /* Not an owned entity, don't make a cell patch. */
114     if (flg) continue;
115     ierr = PetscHSetIAdd(ht, opoint);CHKERRQ(ierr);
116   }
117 
118   /* Now build the overlap for the patch */
119   for (overlapi = 0; overlapi < patch->pardecomp_overlap; ++overlapi) {
120     PetscInt index = 0;
121     PetscInt *htpoints = NULL;
122     PetscInt htsize;
123     PetscInt i;
124 
125     ierr = PetscHSetIGetSize(ht, &htsize);CHKERRQ(ierr);
126     ierr = PetscMalloc1(htsize, &htpoints);CHKERRQ(ierr);
127     ierr = PetscHSetIGetElems(ht, &index, htpoints);CHKERRQ(ierr);
128 
129     for (i = 0; i < htsize; ++i) {
130       PetscInt hpoint = htpoints[i];
131       PetscInt si;
132 
133       ierr = DMPlexGetTransitiveClosure(dm, hpoint, PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
134       for (si = 0; si < starSize*2; si += 2) {
135         const PetscInt starp = star[si];
136         PetscInt       closureSize;
137         PetscInt      *closure = NULL, ci;
138 
139         /* now loop over all entities in the closure of starp */
140         ierr = DMPlexGetTransitiveClosure(dm, starp, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
141         for (ci = 0; ci < closureSize*2; ci += 2) {
142           const PetscInt closstarp = closure[ci];
143           ierr = PetscHSetIAdd(ht, closstarp);CHKERRQ(ierr);
144         }
145         ierr = DMPlexRestoreTransitiveClosure(dm, starp, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
146       }
147       ierr = DMPlexRestoreTransitiveClosure(dm, hpoint, PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
148     }
149     ierr = PetscFree(htpoints);CHKERRQ(ierr);
150   }
151 
152   PetscFunctionReturn(0);
153 }
154 
155 /* The user's already set the patches in patch->userIS. Build the hash tables */
156 static PetscErrorCode PCPatchConstruct_User(void *vpatch, DM dm, PetscInt point, PetscHSetI ht)
157 {
158   PC_PATCH       *patch   = (PC_PATCH *) vpatch;
159   IS              patchis = patch->userIS[point];
160   PetscInt        n;
161   const PetscInt *patchdata;
162   PetscInt        pStart, pEnd, i;
163   PetscErrorCode  ierr;
164 
165   PetscFunctionBegin;
166   ierr = PetscHSetIClear(ht);CHKERRQ(ierr);
167   ierr = DMPlexGetChart(dm, &pStart, &pEnd);CHKERRQ(ierr);
168   ierr = ISGetLocalSize(patchis, &n);CHKERRQ(ierr);
169   ierr = ISGetIndices(patchis, &patchdata);CHKERRQ(ierr);
170   for (i = 0; i < n; ++i) {
171     const PetscInt ownedpoint = patchdata[i];
172 
173     if (ownedpoint < pStart || ownedpoint >= pEnd) {
174       SETERRQ3(PetscObjectComm((PetscObject) dm), PETSC_ERR_ARG_OUTOFRANGE, "Mesh point %D was not in [%D, %D)", ownedpoint, pStart, pEnd);
175     }
176     ierr = PetscHSetIAdd(ht, ownedpoint);CHKERRQ(ierr);
177   }
178   ierr = ISRestoreIndices(patchis, &patchdata);CHKERRQ(ierr);
179   PetscFunctionReturn(0);
180 }
181 
182 static PetscErrorCode PCPatchCreateDefaultSF_Private(PC pc, PetscInt n, const PetscSF *sf, const PetscInt *bs)
183 {
184   PC_PATCH      *patch = (PC_PATCH *) pc->data;
185   PetscInt       i;
186   PetscErrorCode ierr;
187 
188   PetscFunctionBegin;
189   if (n == 1 && bs[0] == 1) {
190     patch->defaultSF = sf[0];
191     ierr = PetscObjectReference((PetscObject) patch->defaultSF);CHKERRQ(ierr);
192   } else {
193     PetscInt     allRoots = 0, allLeaves = 0;
194     PetscInt     leafOffset = 0;
195     PetscInt    *ilocal = NULL;
196     PetscSFNode *iremote = NULL;
197     PetscInt    *remoteOffsets = NULL;
198     PetscInt     index = 0;
199     PetscHMapI   rankToIndex;
200     PetscInt     numRanks = 0;
201     PetscSFNode *remote = NULL;
202     PetscSF      rankSF;
203     PetscInt    *ranks = NULL;
204     PetscInt    *offsets = NULL;
205     MPI_Datatype contig;
206     PetscHSetI   ranksUniq;
207 
208     /* First figure out how many dofs there are in the concatenated numbering.
209      * allRoots: number of owned global dofs;
210      * allLeaves: number of visible dofs (global + ghosted).
211      */
212     for (i = 0; i < n; ++i) {
213       PetscInt nroots, nleaves;
214 
215       ierr = PetscSFGetGraph(sf[i], &nroots, &nleaves, NULL, NULL);CHKERRQ(ierr);
216       allRoots  += nroots * bs[i];
217       allLeaves += nleaves * bs[i];
218     }
219     ierr = PetscMalloc1(allLeaves, &ilocal);CHKERRQ(ierr);
220     ierr = PetscMalloc1(allLeaves, &iremote);CHKERRQ(ierr);
221     /* Now build an SF that just contains process connectivity. */
222     ierr = PetscHSetICreate(&ranksUniq);CHKERRQ(ierr);
223     for (i = 0; i < n; ++i) {
224       const PetscMPIInt *ranks = NULL;
225       PetscInt           nranks, j;
226 
227       ierr = PetscSFSetUp(sf[i]);CHKERRQ(ierr);
228       ierr = PetscSFGetRanks(sf[i], &nranks, &ranks, NULL, NULL, NULL);CHKERRQ(ierr);
229       /* These are all the ranks who communicate with me. */
230       for (j = 0; j < nranks; ++j) {
231         ierr = PetscHSetIAdd(ranksUniq, (PetscInt) ranks[j]);CHKERRQ(ierr);
232       }
233     }
234     ierr = PetscHSetIGetSize(ranksUniq, &numRanks);CHKERRQ(ierr);
235     ierr = PetscMalloc1(numRanks, &remote);CHKERRQ(ierr);
236     ierr = PetscMalloc1(numRanks, &ranks);CHKERRQ(ierr);
237     ierr = PetscHSetIGetElems(ranksUniq, &index, ranks);CHKERRQ(ierr);
238 
239     ierr = PetscHMapICreate(&rankToIndex);CHKERRQ(ierr);
240     for (i = 0; i < numRanks; ++i) {
241       remote[i].rank  = ranks[i];
242       remote[i].index = 0;
243       ierr = PetscHMapISet(rankToIndex, ranks[i], i);CHKERRQ(ierr);
244     }
245     ierr = PetscFree(ranks);CHKERRQ(ierr);
246     ierr = PetscHSetIDestroy(&ranksUniq);CHKERRQ(ierr);
247     ierr = PetscSFCreate(PetscObjectComm((PetscObject) pc), &rankSF);CHKERRQ(ierr);
248     ierr = PetscSFSetGraph(rankSF, 1, numRanks, NULL, PETSC_OWN_POINTER, remote, PETSC_OWN_POINTER);CHKERRQ(ierr);
249     ierr = PetscSFSetUp(rankSF);CHKERRQ(ierr);
250     /* OK, use it to communicate the root offset on the remote
251      * processes for each subspace. */
252     ierr = PetscMalloc1(n, &offsets);CHKERRQ(ierr);
253     ierr = PetscMalloc1(n*numRanks, &remoteOffsets);CHKERRQ(ierr);
254 
255     offsets[0] = 0;
256     for (i = 1; i < n; ++i) {
257       PetscInt nroots;
258 
259       ierr = PetscSFGetGraph(sf[i-1], &nroots, NULL, NULL, NULL);CHKERRQ(ierr);
260       offsets[i] = offsets[i-1] + nroots*bs[i-1];
261     }
262     /* Offsets are the offsets on the current process of the
263      * global dof numbering for the subspaces. */
264     ierr = MPI_Type_contiguous(n, MPIU_INT, &contig);CHKERRQ(ierr);
265     ierr = MPI_Type_commit(&contig);CHKERRQ(ierr);
266 
267     ierr = PetscSFBcastBegin(rankSF, contig, offsets, remoteOffsets);CHKERRQ(ierr);
268     ierr = PetscSFBcastEnd(rankSF, contig, offsets, remoteOffsets);CHKERRQ(ierr);
269     ierr = MPI_Type_free(&contig);CHKERRQ(ierr);
270     ierr = PetscFree(offsets);CHKERRQ(ierr);
271     ierr = PetscSFDestroy(&rankSF);CHKERRQ(ierr);
272     /* Now remoteOffsets contains the offsets on the remote
273      * processes who communicate with me.  So now we can
274      * concatenate the list of SFs into a single one. */
275     index = 0;
276     for (i = 0; i < n; ++i) {
277       const PetscSFNode *remote = NULL;
278       const PetscInt    *local  = NULL;
279       PetscInt           nroots, nleaves, j;
280 
281       ierr = PetscSFGetGraph(sf[i], &nroots, &nleaves, &local, &remote);CHKERRQ(ierr);
282       for (j = 0; j < nleaves; ++j) {
283         PetscInt rank = remote[j].rank;
284         PetscInt idx, rootOffset, k;
285 
286         ierr = PetscHMapIGet(rankToIndex, rank, &idx);CHKERRQ(ierr);
287         if (idx == -1) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Didn't find rank, huh?");
288         /* Offset on given rank for ith subspace */
289         rootOffset = remoteOffsets[n*idx + i];
290         for (k = 0; k < bs[i]; ++k) {
291           ilocal[index]        = (local ? local[j] : j)*bs[i] + k + leafOffset;
292           iremote[index].rank  = remote[j].rank;
293           iremote[index].index = remote[j].index*bs[i] + k + rootOffset;
294           ++index;
295         }
296       }
297       leafOffset += nleaves * bs[i];
298     }
299     ierr = PetscHMapIDestroy(&rankToIndex);CHKERRQ(ierr);
300     ierr = PetscFree(remoteOffsets);CHKERRQ(ierr);
301     ierr = PetscSFCreate(PetscObjectComm((PetscObject)pc), &patch->defaultSF);CHKERRQ(ierr);
302     ierr = PetscSFSetGraph(patch->defaultSF, allRoots, allLeaves, ilocal, PETSC_OWN_POINTER, iremote, PETSC_OWN_POINTER);CHKERRQ(ierr);
303   }
304   PetscFunctionReturn(0);
305 }
306 
307 /* TODO: Docs */
308 PetscErrorCode PCPatchSetIgnoreDim(PC pc, PetscInt dim)
309 {
310   PC_PATCH *patch = (PC_PATCH *) pc->data;
311   PetscFunctionBegin;
312   patch->ignoredim = dim;
313   PetscFunctionReturn(0);
314 }
315 
316 /* TODO: Docs */
317 PetscErrorCode PCPatchGetIgnoreDim(PC pc, PetscInt *dim)
318 {
319   PC_PATCH *patch = (PC_PATCH *) pc->data;
320   PetscFunctionBegin;
321   *dim = patch->ignoredim;
322   PetscFunctionReturn(0);
323 }
324 
325 /* TODO: Docs */
326 PetscErrorCode PCPatchSetSaveOperators(PC pc, PetscBool flg)
327 {
328   PC_PATCH *patch = (PC_PATCH *) pc->data;
329   PetscFunctionBegin;
330   patch->save_operators = flg;
331   PetscFunctionReturn(0);
332 }
333 
334 /* TODO: Docs */
335 PetscErrorCode PCPatchGetSaveOperators(PC pc, PetscBool *flg)
336 {
337   PC_PATCH *patch = (PC_PATCH *) pc->data;
338   PetscFunctionBegin;
339   *flg = patch->save_operators;
340   PetscFunctionReturn(0);
341 }
342 
343 /* TODO: Docs */
344 PetscErrorCode PCPatchSetPrecomputeElementTensors(PC pc, PetscBool flg)
345 {
346   PC_PATCH *patch = (PC_PATCH *) pc->data;
347   PetscFunctionBegin;
348   patch->precomputeElementTensors = flg;
349   PetscFunctionReturn(0);
350 }
351 
352 /* TODO: Docs */
353 PetscErrorCode PCPatchGetPrecomputeElementTensors(PC pc, PetscBool *flg)
354 {
355   PC_PATCH *patch = (PC_PATCH *) pc->data;
356   PetscFunctionBegin;
357   *flg = patch->precomputeElementTensors;
358   PetscFunctionReturn(0);
359 }
360 
361 /* TODO: Docs */
362 PetscErrorCode PCPatchSetPartitionOfUnity(PC pc, PetscBool flg)
363 {
364   PC_PATCH *patch = (PC_PATCH *) pc->data;
365   PetscFunctionBegin;
366   patch->partition_of_unity = flg;
367   PetscFunctionReturn(0);
368 }
369 
370 /* TODO: Docs */
371 PetscErrorCode PCPatchGetPartitionOfUnity(PC pc, PetscBool *flg)
372 {
373   PC_PATCH *patch = (PC_PATCH *) pc->data;
374   PetscFunctionBegin;
375   *flg = patch->partition_of_unity;
376   PetscFunctionReturn(0);
377 }
378 
379 /* TODO: Docs */
380 PetscErrorCode PCPatchSetLocalComposition(PC pc, PCCompositeType type)
381 {
382   PC_PATCH *patch = (PC_PATCH *) pc->data;
383   PetscFunctionBegin;
384   if (type != PC_COMPOSITE_ADDITIVE && type != PC_COMPOSITE_MULTIPLICATIVE) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_SUP,"Only supports additive or multiplicative as the local type");
385   patch->local_composition_type = type;
386   PetscFunctionReturn(0);
387 }
388 
389 /* TODO: Docs */
390 PetscErrorCode PCPatchGetLocalComposition(PC pc, PCCompositeType *type)
391 {
392   PC_PATCH *patch = (PC_PATCH *) pc->data;
393   PetscFunctionBegin;
394   *type = patch->local_composition_type;
395   PetscFunctionReturn(0);
396 }
397 
398 /* TODO: Docs */
399 PetscErrorCode PCPatchSetSubMatType(PC pc, MatType sub_mat_type)
400 {
401   PC_PATCH      *patch = (PC_PATCH *) pc->data;
402   PetscErrorCode ierr;
403 
404   PetscFunctionBegin;
405   if (patch->sub_mat_type) {ierr = PetscFree(patch->sub_mat_type);CHKERRQ(ierr);}
406   ierr = PetscStrallocpy(sub_mat_type, (char **) &patch->sub_mat_type);CHKERRQ(ierr);
407   PetscFunctionReturn(0);
408 }
409 
410 /* TODO: Docs */
411 PetscErrorCode PCPatchGetSubMatType(PC pc, MatType *sub_mat_type)
412 {
413   PC_PATCH *patch = (PC_PATCH *) pc->data;
414   PetscFunctionBegin;
415   *sub_mat_type = patch->sub_mat_type;
416   PetscFunctionReturn(0);
417 }
418 
419 /* TODO: Docs */
420 PetscErrorCode PCPatchSetCellNumbering(PC pc, PetscSection cellNumbering)
421 {
422   PC_PATCH      *patch = (PC_PATCH *) pc->data;
423   PetscErrorCode ierr;
424 
425   PetscFunctionBegin;
426   patch->cellNumbering = cellNumbering;
427   ierr = PetscObjectReference((PetscObject) cellNumbering);CHKERRQ(ierr);
428   PetscFunctionReturn(0);
429 }
430 
431 /* TODO: Docs */
432 PetscErrorCode PCPatchGetCellNumbering(PC pc, PetscSection *cellNumbering)
433 {
434   PC_PATCH *patch = (PC_PATCH *) pc->data;
435   PetscFunctionBegin;
436   *cellNumbering = patch->cellNumbering;
437   PetscFunctionReturn(0);
438 }
439 
440 /* TODO: Docs */
441 PetscErrorCode PCPatchSetConstructType(PC pc, PCPatchConstructType ctype, PetscErrorCode (*func)(PC, PetscInt *, IS **, IS *, void *), void *ctx)
442 {
443   PC_PATCH *patch = (PC_PATCH *) pc->data;
444 
445   PetscFunctionBegin;
446   patch->ctype = ctype;
447   switch (ctype) {
448   case PC_PATCH_STAR:
449     patch->user_patches     = PETSC_FALSE;
450     patch->patchconstructop = PCPatchConstruct_Star;
451     break;
452   case PC_PATCH_VANKA:
453     patch->user_patches     = PETSC_FALSE;
454     patch->patchconstructop = PCPatchConstruct_Vanka;
455     break;
456   case PC_PATCH_PARDECOMP:
457     patch->user_patches     = PETSC_FALSE;
458     patch->patchconstructop = PCPatchConstruct_Pardecomp;
459     break;
460   case PC_PATCH_USER:
461   case PC_PATCH_PYTHON:
462     patch->user_patches     = PETSC_TRUE;
463     patch->patchconstructop = PCPatchConstruct_User;
464     if (func) {
465       patch->userpatchconstructionop = func;
466       patch->userpatchconstructctx   = ctx;
467     }
468     break;
469   default:
470     SETERRQ1(PetscObjectComm((PetscObject) pc), PETSC_ERR_USER, "Unknown patch construction type %D", (PetscInt) patch->ctype);
471   }
472   PetscFunctionReturn(0);
473 }
474 
475 /* TODO: Docs */
476 PetscErrorCode PCPatchGetConstructType(PC pc, PCPatchConstructType *ctype, PetscErrorCode (**func)(PC, PetscInt *, IS **, IS *, void *), void **ctx)
477 {
478   PC_PATCH *patch = (PC_PATCH *) pc->data;
479 
480   PetscFunctionBegin;
481   *ctype = patch->ctype;
482   switch (patch->ctype) {
483   case PC_PATCH_STAR:
484   case PC_PATCH_VANKA:
485   case PC_PATCH_PARDECOMP:
486     break;
487   case PC_PATCH_USER:
488   case PC_PATCH_PYTHON:
489     *func = patch->userpatchconstructionop;
490     *ctx  = patch->userpatchconstructctx;
491     break;
492   default:
493     SETERRQ1(PetscObjectComm((PetscObject) pc), PETSC_ERR_USER, "Unknown patch construction type %D", (PetscInt) patch->ctype);
494   }
495   PetscFunctionReturn(0);
496 }
497 
498 /* TODO: Docs */
499 PetscErrorCode PCPatchSetDiscretisationInfo(PC pc, PetscInt nsubspaces, DM *dms, PetscInt *bs, PetscInt *nodesPerCell, const PetscInt **cellNodeMap,
500                                             const PetscInt *subspaceOffsets, PetscInt numGhostBcs, const PetscInt *ghostBcNodes, PetscInt numGlobalBcs, const PetscInt *globalBcNodes)
501 {
502   PC_PATCH      *patch = (PC_PATCH *) pc->data;
503   DM             dm;
504   PetscSF       *sfs;
505   PetscInt       cStart, cEnd, i, j;
506   PetscErrorCode ierr;
507 
508   PetscFunctionBegin;
509   ierr = PCGetDM(pc, &dm);CHKERRQ(ierr);
510   ierr = DMPlexGetHeightStratum(dm, 0, &cStart, &cEnd);CHKERRQ(ierr);
511   ierr = PetscMalloc1(nsubspaces, &sfs);CHKERRQ(ierr);
512   ierr = PetscMalloc1(nsubspaces, &patch->dofSection);CHKERRQ(ierr);
513   ierr = PetscMalloc1(nsubspaces, &patch->bs);CHKERRQ(ierr);
514   ierr = PetscMalloc1(nsubspaces, &patch->nodesPerCell);CHKERRQ(ierr);
515   ierr = PetscMalloc1(nsubspaces, &patch->cellNodeMap);CHKERRQ(ierr);
516   ierr = PetscMalloc1(nsubspaces+1, &patch->subspaceOffsets);CHKERRQ(ierr);
517 
518   patch->nsubspaces       = nsubspaces;
519   patch->totalDofsPerCell = 0;
520   for (i = 0; i < nsubspaces; ++i) {
521     ierr = DMGetDefaultSection(dms[i], &patch->dofSection[i]);CHKERRQ(ierr);
522     ierr = PetscObjectReference((PetscObject) patch->dofSection[i]);CHKERRQ(ierr);
523     ierr = DMGetDefaultSF(dms[i], &sfs[i]);CHKERRQ(ierr);
524     patch->bs[i]              = bs[i];
525     patch->nodesPerCell[i]    = nodesPerCell[i];
526     patch->totalDofsPerCell  += nodesPerCell[i]*bs[i];
527     ierr = PetscMalloc1((cEnd-cStart)*nodesPerCell[i], &patch->cellNodeMap[i]);CHKERRQ(ierr);
528     for (j = 0; j < (cEnd-cStart)*nodesPerCell[i]; ++j) patch->cellNodeMap[i][j] = cellNodeMap[i][j];
529     patch->subspaceOffsets[i] = subspaceOffsets[i];
530   }
531   ierr = PCPatchCreateDefaultSF_Private(pc, nsubspaces, sfs, patch->bs);CHKERRQ(ierr);
532   ierr = PetscFree(sfs);CHKERRQ(ierr);
533 
534   patch->subspaceOffsets[nsubspaces] = subspaceOffsets[nsubspaces];
535   ierr = ISCreateGeneral(PETSC_COMM_SELF, numGhostBcs, ghostBcNodes, PETSC_COPY_VALUES, &patch->ghostBcNodes);CHKERRQ(ierr);
536   ierr = ISCreateGeneral(PETSC_COMM_SELF, numGlobalBcs, globalBcNodes, PETSC_COPY_VALUES, &patch->globalBcNodes);CHKERRQ(ierr);
537   PetscFunctionReturn(0);
538 }
539 
540 /* TODO: Docs */
541 PetscErrorCode PCPatchSetDiscretisationInfoCombined(PC pc, DM dm, PetscInt *nodesPerCell, const PetscInt **cellNodeMap, PetscInt numGhostBcs, const PetscInt *ghostBcNodes, PetscInt numGlobalBcs, const PetscInt *globalBcNodes)
542 {
543   PC_PATCH      *patch = (PC_PATCH *) pc->data;
544   PetscInt       cStart, cEnd, i, j;
545   PetscErrorCode ierr;
546 
547   PetscFunctionBegin;
548   patch->combined = PETSC_TRUE;
549   ierr = DMPlexGetHeightStratum(dm, 0, &cStart, &cEnd);CHKERRQ(ierr);
550   ierr = DMGetNumFields(dm, &patch->nsubspaces);CHKERRQ(ierr);
551   ierr = PetscCalloc1(patch->nsubspaces, &patch->dofSection);CHKERRQ(ierr);
552   ierr = PetscMalloc1(patch->nsubspaces, &patch->bs);CHKERRQ(ierr);
553   ierr = PetscMalloc1(patch->nsubspaces, &patch->nodesPerCell);CHKERRQ(ierr);
554   ierr = PetscMalloc1(patch->nsubspaces, &patch->cellNodeMap);CHKERRQ(ierr);
555   ierr = PetscCalloc1(patch->nsubspaces+1, &patch->subspaceOffsets);CHKERRQ(ierr);
556   ierr = DMGetDefaultSection(dm, &patch->dofSection[0]);CHKERRQ(ierr);
557   ierr = PetscObjectReference((PetscObject) patch->dofSection[0]);CHKERRQ(ierr);
558   ierr = PetscSectionGetStorageSize(patch->dofSection[0], &patch->subspaceOffsets[patch->nsubspaces]);CHKERRQ(ierr);
559   patch->totalDofsPerCell = 0;
560   for (i = 0; i < patch->nsubspaces; ++i) {
561     patch->bs[i]             = 1;
562     patch->nodesPerCell[i]   = nodesPerCell[i];
563     patch->totalDofsPerCell += nodesPerCell[i];
564     ierr = PetscMalloc1((cEnd-cStart)*nodesPerCell[i], &patch->cellNodeMap[i]);CHKERRQ(ierr);
565     for (j = 0; j < (cEnd-cStart)*nodesPerCell[i]; ++j) patch->cellNodeMap[i][j] = cellNodeMap[i][j];
566   }
567   ierr = DMGetDefaultSF(dm, &patch->defaultSF);CHKERRQ(ierr);
568   ierr = PetscObjectReference((PetscObject) patch->defaultSF);CHKERRQ(ierr);
569   ierr = ISCreateGeneral(PETSC_COMM_SELF, numGhostBcs, ghostBcNodes, PETSC_COPY_VALUES, &patch->ghostBcNodes);CHKERRQ(ierr);
570   ierr = ISCreateGeneral(PETSC_COMM_SELF, numGlobalBcs, globalBcNodes, PETSC_COPY_VALUES, &patch->globalBcNodes);CHKERRQ(ierr);
571   PetscFunctionReturn(0);
572 }
573 
574 /*@C
575 
576   PCPatchSetComputeFunction - Set the callback used to compute patch residuals
577 
578   Logically collective on PC
579 
580   Input Parameters:
581 + pc   - The PC
582 . func - The callback
583 - ctx  - The user context
584 
585   Calling sequence of func:
586 $   func (PC pc,PetscInt point,Vec x,Vec f,IS cellIS,PetscInt n,const PetscInt* dofsArray,const PetscInt* dofsArrayWithAll,void* ctx)
587 
588 +  pc               - The PC
589 .  point            - The point
590 .  x                - The input solution (not used in linear problems)
591 .  f                - The patch residual vector
592 .  cellIS           - An array of the cell numbers
593 .  n                - The size of dofsArray
594 .  dofsArray        - The dofmap for the dofs to be solved for
595 .  dofsArrayWithAll - The dofmap for all dofs on the patch
596 -  ctx              - The user context
597 
598   Level: advanced
599 
600   Notes:
601   The matrix entries have been set to zero before the call.
602 
603 .seealso: PCPatchSetComputeOperator(), PCPatchGetComputeOperator(), PCPatchSetDiscretisationInfo()
604 @*/
605 PetscErrorCode PCPatchSetComputeFunction(PC pc, PetscErrorCode (*func)(PC, PetscInt, Vec, Vec, IS, PetscInt, const PetscInt *, const PetscInt *, void *), void *ctx)
606 {
607   PC_PATCH *patch = (PC_PATCH *) pc->data;
608 
609   PetscFunctionBegin;
610   patch->usercomputef    = func;
611   patch->usercomputefctx = ctx;
612   PetscFunctionReturn(0);
613 }
614 
615 /*@C
616 
617   PCPatchSetComputeFunctionInteriorFacets - Set the callback used to compute facet integrals for patch residuals
618 
619   Logically collective on PC
620 
621   Input Parameters:
622 + pc   - The PC
623 . func - The callback
624 - ctx  - The user context
625 
626   Calling sequence of func:
627 $   func (PC pc,PetscInt point,Vec x,Vec f,IS facetIS,PetscInt n,const PetscInt* dofsArray,const PetscInt* dofsArrayWithAll,void* ctx)
628 
629 +  pc               - The PC
630 .  point            - The point
631 .  x                - The input solution (not used in linear problems)
632 .  f                - The patch residual vector
633 .  facetIS          - An array of the facet numbers
634 .  n                - The size of dofsArray
635 .  dofsArray        - The dofmap for the dofs to be solved for
636 .  dofsArrayWithAll - The dofmap for all dofs on the patch
637 -  ctx              - The user context
638 
639   Level: advanced
640 
641   Notes:
642   The matrix entries have been set to zero before the call.
643 
644 .seealso: PCPatchSetComputeOperator(), PCPatchGetComputeOperator(), PCPatchSetDiscretisationInfo()
645 @*/
646 PetscErrorCode PCPatchSetComputeFunctionInteriorFacets(PC pc, PetscErrorCode (*func)(PC, PetscInt, Vec, Vec, IS, PetscInt, const PetscInt *, const PetscInt *, void *), void *ctx)
647 {
648   PC_PATCH *patch = (PC_PATCH *) pc->data;
649 
650   PetscFunctionBegin;
651   patch->usercomputefintfacet    = func;
652   patch->usercomputefintfacetctx = ctx;
653   PetscFunctionReturn(0);
654 }
655 
656 /*@C
657 
658   PCPatchSetComputeOperator - Set the callback used to compute patch matrices
659 
660   Logically collective on PC
661 
662   Input Parameters:
663 + pc   - The PC
664 . func - The callback
665 - ctx  - The user context
666 
667   Calling sequence of func:
668 $   func (PC pc,PetscInt point,Vec x,Mat mat,IS facetIS,PetscInt n,const PetscInt* dofsArray,const PetscInt* dofsArrayWithAll,void* ctx)
669 
670 +  pc               - The PC
671 .  point            - The point
672 .  x                - The input solution (not used in linear problems)
673 .  mat              - The patch matrix
674 .  cellIS           - An array of the cell numbers
675 .  n                - The size of dofsArray
676 .  dofsArray        - The dofmap for the dofs to be solved for
677 .  dofsArrayWithAll - The dofmap for all dofs on the patch
678 -  ctx              - The user context
679 
680   Level: advanced
681 
682   Notes:
683   The matrix entries have been set to zero before the call.
684 
685 .seealso: PCPatchGetComputeOperator(), PCPatchSetComputeFunction(), PCPatchSetDiscretisationInfo()
686 @*/
687 PetscErrorCode PCPatchSetComputeOperator(PC pc, PetscErrorCode (*func)(PC, PetscInt, Vec, Mat, IS, PetscInt, const PetscInt *, const PetscInt *, void *), void *ctx)
688 {
689   PC_PATCH *patch = (PC_PATCH *) pc->data;
690 
691   PetscFunctionBegin;
692   patch->usercomputeop    = func;
693   patch->usercomputeopctx = ctx;
694   PetscFunctionReturn(0);
695 }
696 
697 /*@C
698 
699   PCPatchSetComputeOperatorInteriorFacets - Set the callback used to compute facet integrals for patch matrices
700 
701   Logically collective on PC
702 
703   Input Parameters:
704 + pc   - The PC
705 . func - The callback
706 - ctx  - The user context
707 
708   Calling sequence of func:
709 $   func (PC pc,PetscInt point,Vec x,Mat mat,IS facetIS,PetscInt n,const PetscInt* dofsArray,const PetscInt* dofsArrayWithAll,void* ctx)
710 
711 +  pc               - The PC
712 .  point            - The point
713 .  x                - The input solution (not used in linear problems)
714 .  mat              - The patch matrix
715 .  facetIS          - An array of the facet numbers
716 .  n                - The size of dofsArray
717 .  dofsArray        - The dofmap for the dofs to be solved for
718 .  dofsArrayWithAll - The dofmap for all dofs on the patch
719 -  ctx              - The user context
720 
721   Level: advanced
722 
723   Notes:
724   The matrix entries have been set to zero before the call.
725 
726 .seealso: PCPatchGetComputeOperator(), PCPatchSetComputeFunction(), PCPatchSetDiscretisationInfo()
727 @*/
728 PetscErrorCode PCPatchSetComputeOperatorInteriorFacets(PC pc, PetscErrorCode (*func)(PC, PetscInt, Vec, Mat, IS, PetscInt, const PetscInt *, const PetscInt *, void *), void *ctx)
729 {
730   PC_PATCH *patch = (PC_PATCH *) pc->data;
731 
732   PetscFunctionBegin;
733   patch->usercomputeopintfacet    = func;
734   patch->usercomputeopintfacetctx = ctx;
735   PetscFunctionReturn(0);
736 }
737 
738 /* On entry, ht contains the topological entities whose dofs we are responsible for solving for;
739    on exit, cht contains all the topological entities we need to compute their residuals.
740    In full generality this should incorporate knowledge of the sparsity pattern of the matrix;
741    here we assume a standard FE sparsity pattern.*/
742 /* TODO: Use DMPlexGetAdjacency() */
743 static PetscErrorCode PCPatchCompleteCellPatch(PC pc, PetscHSetI ht, PetscHSetI cht)
744 {
745   DM             dm;
746   PC_PATCH      *patch = (PC_PATCH *) pc->data;
747   PetscHashIter  hi;
748   PetscInt       point;
749   PetscInt      *star = NULL, *closure = NULL;
750   PetscInt       ignoredim, iStart = 0, iEnd = -1, starSize, closureSize, si, ci;
751   PetscInt      *fStar = NULL, *fClosure = NULL;
752   PetscInt       fBegin, fEnd, fsi, fci, fStarSize, fClosureSize;
753   PetscErrorCode ierr;
754 
755   PetscFunctionBegin;
756   ierr = PCGetDM(pc, &dm);CHKERRQ(ierr);
757   ierr = DMPlexGetHeightStratum(dm, 1, &fBegin, &fEnd);CHKERRQ(ierr);
758   ierr = PCPatchGetIgnoreDim(pc, &ignoredim);CHKERRQ(ierr);
759   if (ignoredim >= 0) {ierr = DMPlexGetDepthStratum(dm, ignoredim, &iStart, &iEnd);CHKERRQ(ierr);}
760   ierr = PetscHSetIClear(cht);CHKERRQ(ierr);
761   PetscHashIterBegin(ht, hi);
762   while (!PetscHashIterAtEnd(ht, hi)) {
763 
764     PetscHashIterGetKey(ht, hi, point);
765     PetscHashIterNext(ht, hi);
766 
767     /* Loop over all the cells that this point connects to */
768     ierr = DMPlexGetTransitiveClosure(dm, point, PETSC_FALSE, &starSize, &star);CHKERRQ(ierr);
769     for (si = 0; si < starSize*2; si += 2) {
770       const PetscInt ownedpoint = star[si];
771       /* TODO Check for point in cht before running through closure again */
772       /* now loop over all entities in the closure of that cell */
773       ierr = DMPlexGetTransitiveClosure(dm, ownedpoint, PETSC_TRUE, &closureSize, &closure);CHKERRQ(ierr);
774       for (ci = 0; ci < closureSize*2; ci += 2) {
775         const PetscInt seenpoint = closure[ci];
776         if (ignoredim >= 0 && seenpoint >= iStart && seenpoint < iEnd) continue;
777         ierr = PetscHSetIAdd(cht, seenpoint);CHKERRQ(ierr);
778         /* Facet integrals couple dofs across facets, so in that case for each of
779          * the facets we need to add all dofs on the other side of the facet to
780          * the seen dofs. */
781         if(patch->usercomputeopintfacet){
782           if(fBegin <= seenpoint && seenpoint < fEnd){
783             ierr = DMPlexGetTransitiveClosure(dm, seenpoint, PETSC_FALSE, &fStarSize, &fStar);CHKERRQ(ierr);
784             for (fsi = 0; fsi < fStarSize*2; fsi += 2) {
785               ierr = DMPlexGetTransitiveClosure(dm, fStar[fsi], PETSC_TRUE, &fClosureSize, &fClosure);CHKERRQ(ierr);
786               for (fci = 0; fci < fClosureSize*2; fci += 2) {
787                 ierr = PetscHSetIAdd(cht, fClosure[fci]);CHKERRQ(ierr);
788               }
789               ierr = DMPlexRestoreTransitiveClosure(dm, fStar[fsi], PETSC_TRUE, NULL, &fClosure);CHKERRQ(ierr);
790             }
791             ierr = DMPlexRestoreTransitiveClosure(dm, seenpoint, PETSC_FALSE, NULL, &fStar);CHKERRQ(ierr);
792           }
793         }
794       }
795       ierr = DMPlexRestoreTransitiveClosure(dm, ownedpoint, PETSC_TRUE, NULL, &closure);CHKERRQ(ierr);
796     }
797     ierr = DMPlexRestoreTransitiveClosure(dm, point, PETSC_FALSE, NULL, &star);CHKERRQ(ierr);
798   }
799   PetscFunctionReturn(0);
800 }
801 
802 static PetscErrorCode PCPatchGetGlobalDofs(PC pc, PetscSection dofSection[], PetscInt f, PetscBool combined, PetscInt p, PetscInt *dof, PetscInt *off)
803 {
804   PetscErrorCode ierr;
805 
806   PetscFunctionBegin;
807   if (combined) {
808     if (f < 0) {
809       if (dof) {ierr = PetscSectionGetDof(dofSection[0], p, dof);CHKERRQ(ierr);}
810       if (off) {ierr = PetscSectionGetOffset(dofSection[0], p, off);CHKERRQ(ierr);}
811     } else {
812       if (dof) {ierr = PetscSectionGetFieldDof(dofSection[0], p, f, dof);CHKERRQ(ierr);}
813       if (off) {ierr = PetscSectionGetFieldOffset(dofSection[0], p, f, off);CHKERRQ(ierr);}
814     }
815   } else {
816     if (f < 0) {
817       PC_PATCH *patch = (PC_PATCH *) pc->data;
818       PetscInt  fdof, g;
819 
820       if (dof) {
821         *dof = 0;
822         for (g = 0; g < patch->nsubspaces; ++g) {
823           ierr = PetscSectionGetDof(dofSection[g], p, &fdof);CHKERRQ(ierr);
824           *dof += fdof;
825         }
826       }
827       if (off) {
828         *off = 0;
829         for (g = 0; g < patch->nsubspaces; ++g) {
830           ierr = PetscSectionGetOffset(dofSection[g], p, &fdof);CHKERRQ(ierr);
831           *off += fdof;
832         }
833       }
834     } else {
835       if (dof) {ierr = PetscSectionGetDof(dofSection[f], p, dof);CHKERRQ(ierr);}
836       if (off) {ierr = PetscSectionGetOffset(dofSection[f], p, off);CHKERRQ(ierr);}
837     }
838   }
839   PetscFunctionReturn(0);
840 }
841 
842 /* Given a hash table with a set of topological entities (pts), compute the degrees of
843    freedom in global concatenated numbering on those entities.
844    For Vanka smoothing, this needs to do something special: ignore dofs of the
845    constraint subspace on entities that aren't the base entity we're building the patch
846    around. */
847 static PetscErrorCode PCPatchGetPointDofs(PC pc, PetscHSetI pts, PetscHSetI dofs, PetscInt base, PetscHSetI* subspaces_to_exclude)
848 {
849   PC_PATCH      *patch = (PC_PATCH *) pc->data;
850   PetscHashIter  hi;
851   PetscInt       ldof, loff;
852   PetscInt       k, p;
853   PetscErrorCode ierr;
854 
855   PetscFunctionBegin;
856   ierr = PetscHSetIClear(dofs);CHKERRQ(ierr);
857   for (k = 0; k < patch->nsubspaces; ++k) {
858     PetscInt subspaceOffset = patch->subspaceOffsets[k];
859     PetscInt bs             = patch->bs[k];
860     PetscInt j, l;
861 
862     if (subspaces_to_exclude != NULL) {
863       PetscBool should_exclude_k = PETSC_FALSE;
864       PetscHSetIHas(*subspaces_to_exclude, k, &should_exclude_k);
865       if (should_exclude_k) {
866         /* only get this subspace dofs at the base entity, not any others */
867         ierr = PCPatchGetGlobalDofs(pc, patch->dofSection, k, patch->combined, base, &ldof, &loff);CHKERRQ(ierr);
868         if (0 == ldof) continue;
869         for (j = loff; j < ldof + loff; ++j) {
870           for (l = 0; l < bs; ++l) {
871             PetscInt dof = bs*j + l + subspaceOffset;
872             ierr = PetscHSetIAdd(dofs, dof);CHKERRQ(ierr);
873           }
874         }
875         continue; /* skip the other dofs of this subspace */
876       }
877     }
878 
879     PetscHashIterBegin(pts, hi);
880     while (!PetscHashIterAtEnd(pts, hi)) {
881       PetscHashIterGetKey(pts, hi, p);
882       PetscHashIterNext(pts, hi);
883       ierr = PCPatchGetGlobalDofs(pc, patch->dofSection, k, patch->combined, p, &ldof, &loff);CHKERRQ(ierr);
884       if (0 == ldof) continue;
885       for (j = loff; j < ldof + loff; ++j) {
886         for (l = 0; l < bs; ++l) {
887           PetscInt dof = bs*j + l + subspaceOffset;
888           ierr = PetscHSetIAdd(dofs, dof);CHKERRQ(ierr);
889         }
890       }
891     }
892   }
893   PetscFunctionReturn(0);
894 }
895 
896 /* Given two hash tables A and B, compute the keys in B that are not in A, and put them in C */
897 static PetscErrorCode PCPatchComputeSetDifference_Private(PetscHSetI A, PetscHSetI B, PetscHSetI C)
898 {
899   PetscHashIter  hi;
900   PetscInt       key;
901   PetscBool      flg;
902   PetscErrorCode ierr;
903 
904   PetscFunctionBegin;
905   ierr = PetscHSetIClear(C);CHKERRQ(ierr);
906   PetscHashIterBegin(B, hi);
907   while (!PetscHashIterAtEnd(B, hi)) {
908     PetscHashIterGetKey(B, hi, key);
909     PetscHashIterNext(B, hi);
910     ierr = PetscHSetIHas(A, key, &flg);CHKERRQ(ierr);
911     if (!flg) {ierr = PetscHSetIAdd(C, key);CHKERRQ(ierr);}
912   }
913   PetscFunctionReturn(0);
914 }
915 
916 /*
917  * PCPatchCreateCellPatches - create patches.
918  *
919  * Input Parameters:
920  * + dm - The DMPlex object defining the mesh
921  *
922  * Output Parameters:
923  * + cellCounts  - Section with counts of cells around each vertex
924  * . cells       - IS of the cell point indices of cells in each patch
925  * . pointCounts - Section with counts of cells around each vertex
926  * - point       - IS of the cell point indices of cells in each patch
927  */
928 static PetscErrorCode PCPatchCreateCellPatches(PC pc)
929 {
930   PC_PATCH       *patch = (PC_PATCH *) pc->data;
931   DMLabel         ghost = NULL;
932   DM              dm, plex;
933   PetscHSetI      ht, cht;
934   PetscSection    cellCounts,  pointCounts, intFacetCounts, extFacetCounts;
935   PetscInt       *cellsArray, *pointsArray, *intFacetsArray, *extFacetsArray, *intFacetsToPatchCell;
936   PetscInt        numCells, numPoints, numIntFacets, numExtFacets;
937   const PetscInt *leaves;
938   PetscInt        nleaves, pStart, pEnd, cStart, cEnd, vStart, vEnd, v;
939   PetscBool       isFiredrake;
940   PetscErrorCode  ierr;
941 
942   PetscFunctionBegin;
943   /* Used to keep track of the cells in the patch. */
944   ierr = PetscHSetICreate(&ht);CHKERRQ(ierr);
945   ierr = PetscHSetICreate(&cht);CHKERRQ(ierr);
946 
947   ierr = PCGetDM(pc, &dm);CHKERRQ(ierr);
948   if (!dm) SETERRQ(PetscObjectComm((PetscObject) pc), PETSC_ERR_ARG_WRONGSTATE, "DM not yet set on patch PC\n");
949   ierr = DMConvert(dm, DMPLEX, &plex);CHKERRQ(ierr);
950   ierr = DMPlexGetChart(plex, &pStart, &pEnd);CHKERRQ(ierr);
951   ierr = DMPlexGetHeightStratum(plex, 0, &cStart, &cEnd);CHKERRQ(ierr);
952 
953   if (patch->user_patches) {
954     ierr = patch->userpatchconstructionop(pc, &patch->npatch, &patch->userIS, &patch->iterationSet, patch->userpatchconstructctx);CHKERRQ(ierr);
955     vStart = 0; vEnd = patch->npatch;
956   } else if (patch->ctype == PC_PATCH_PARDECOMP) {
957     vStart = 0; vEnd = 1;
958   } else if (patch->codim < 0) {
959     if (patch->dim < 0) {ierr = DMPlexGetDepthStratum(plex,  0,            &vStart, &vEnd);CHKERRQ(ierr);}
960     else                {ierr = DMPlexGetDepthStratum(plex,  patch->dim,   &vStart, &vEnd);CHKERRQ(ierr);}
961   } else                {ierr = DMPlexGetHeightStratum(plex, patch->codim, &vStart, &vEnd);CHKERRQ(ierr);}
962   patch->npatch = vEnd - vStart;
963 
964   /* These labels mark the owned points.  We only create patches around points that this process owns. */
965   ierr = DMHasLabel(dm, "pyop2_ghost", &isFiredrake);CHKERRQ(ierr);
966   if (isFiredrake) {
967     ierr = DMGetLabel(dm, "pyop2_ghost", &ghost);CHKERRQ(ierr);
968     ierr = DMLabelCreateIndex(ghost, pStart, pEnd);CHKERRQ(ierr);
969   } else {
970     PetscSF sf;
971 
972     ierr = DMGetPointSF(dm, &sf);CHKERRQ(ierr);
973     ierr = PetscSFGetGraph(sf, NULL, &nleaves, &leaves, NULL);CHKERRQ(ierr);
974     nleaves = PetscMax(nleaves, 0);
975   }
976 
977   ierr = PetscSectionCreate(PETSC_COMM_SELF, &patch->cellCounts);CHKERRQ(ierr);
978   ierr = PetscObjectSetName((PetscObject) patch->cellCounts, "Patch Cell Layout");CHKERRQ(ierr);
979   cellCounts = patch->cellCounts;
980   ierr = PetscSectionSetChart(cellCounts, vStart, vEnd);CHKERRQ(ierr);
981   ierr = PetscSectionCreate(PETSC_COMM_SELF, &patch->pointCounts);CHKERRQ(ierr);
982   ierr = PetscObjectSetName((PetscObject) patch->pointCounts, "Patch Point Layout");CHKERRQ(ierr);
983   pointCounts = patch->pointCounts;
984   ierr = PetscSectionSetChart(pointCounts, vStart, vEnd);CHKERRQ(ierr);
985   ierr = PetscSectionCreate(PETSC_COMM_SELF, &patch->extFacetCounts);CHKERRQ(ierr);
986   ierr = PetscObjectSetName((PetscObject) patch->extFacetCounts, "Patch Exterior Facet Layout");CHKERRQ(ierr);
987   extFacetCounts = patch->extFacetCounts;
988   ierr = PetscSectionSetChart(extFacetCounts, vStart, vEnd);CHKERRQ(ierr);
989   ierr = PetscSectionCreate(PETSC_COMM_SELF, &patch->intFacetCounts);CHKERRQ(ierr);
990   ierr = PetscObjectSetName((PetscObject) patch->intFacetCounts, "Patch Interior Facet Layout");CHKERRQ(ierr);
991   intFacetCounts = patch->intFacetCounts;
992   ierr = PetscSectionSetChart(intFacetCounts, vStart, vEnd);CHKERRQ(ierr);
993   /* Count cells and points in the patch surrounding each entity */
994   PetscInt       fStart, fEnd;
995   ierr = DMPlexGetHeightStratum(dm, 1, &fStart, &fEnd);CHKERRQ(ierr);
996   for (v = vStart; v < vEnd; ++v) {
997     PetscHashIter hi;
998     PetscInt       chtSize, loc = -1;
999     PetscBool      flg;
1000 
1001     if (!patch->user_patches && patch->ctype != PC_PATCH_PARDECOMP) {
1002       if (ghost) {ierr = DMLabelHasPoint(ghost, v, &flg);CHKERRQ(ierr);}
1003       else       {ierr = PetscFindInt(v, nleaves, leaves, &loc);CHKERRQ(ierr); flg = loc >=0 ? PETSC_TRUE : PETSC_FALSE;}
1004       /* Not an owned entity, don't make a cell patch. */
1005       if (flg) continue;
1006     }
1007 
1008     ierr = patch->patchconstructop((void *) patch, dm, v, ht);CHKERRQ(ierr);
1009     ierr = PCPatchCompleteCellPatch(pc, ht, cht);CHKERRQ(ierr);
1010     ierr = PetscHSetIGetSize(cht, &chtSize);CHKERRQ(ierr);
1011     /* empty patch, continue */
1012     if (chtSize == 0) continue;
1013 
1014     /* safe because size(cht) > 0 from above */
1015     PetscHashIterBegin(cht, hi);
1016     while (!PetscHashIterAtEnd(cht, hi)) {
1017       PetscInt point, pdof;
1018 
1019       PetscHashIterGetKey(cht, hi, point);
1020       if (fStart <= point && point < fEnd) {
1021         const PetscInt *support;
1022         PetscInt supportSize, p;
1023         PetscBool interior = PETSC_TRUE;
1024         ierr = DMPlexGetSupport(dm, point, &support);CHKERRQ(ierr);
1025         ierr = DMPlexGetSupportSize(dm, point, &supportSize);CHKERRQ(ierr);
1026         if (supportSize == 1) {
1027           interior = PETSC_FALSE;
1028         } else {
1029           for (p = 0; p < supportSize; p++) {
1030             PetscBool found;
1031             /* FIXME: can I do this while iterating over cht? */
1032             PetscHSetIHas(cht, support[p], &found);
1033             if (!found) {
1034               interior = PETSC_FALSE;
1035               break;
1036             }
1037           }
1038         }
1039         if (interior) {
1040           ierr = PetscSectionAddDof(intFacetCounts, v, 1);CHKERRQ(ierr);
1041         } else {
1042           ierr = PetscSectionAddDof(extFacetCounts, v, 1);CHKERRQ(ierr);
1043         }
1044       }
1045       ierr = PCPatchGetGlobalDofs(pc, patch->dofSection, -1, patch->combined, point, &pdof, NULL);CHKERRQ(ierr);
1046       if (pdof)                            {ierr = PetscSectionAddDof(pointCounts, v, 1);CHKERRQ(ierr);}
1047       if (point >= cStart && point < cEnd) {ierr = PetscSectionAddDof(cellCounts, v, 1);CHKERRQ(ierr);}
1048       PetscHashIterNext(cht, hi);
1049     }
1050   }
1051   if (isFiredrake) {ierr = DMLabelDestroyIndex(ghost);CHKERRQ(ierr);}
1052 
1053   ierr = PetscSectionSetUp(cellCounts);CHKERRQ(ierr);
1054   ierr = PetscSectionGetStorageSize(cellCounts, &numCells);CHKERRQ(ierr);
1055   ierr = PetscMalloc1(numCells, &cellsArray);CHKERRQ(ierr);
1056   ierr = PetscSectionSetUp(pointCounts);CHKERRQ(ierr);
1057   ierr = PetscSectionGetStorageSize(pointCounts, &numPoints);CHKERRQ(ierr);
1058   ierr = PetscMalloc1(numPoints, &pointsArray);CHKERRQ(ierr);
1059 
1060   ierr = PetscSectionSetUp(intFacetCounts);CHKERRQ(ierr);
1061   ierr = PetscSectionSetUp(extFacetCounts);CHKERRQ(ierr);
1062   ierr = PetscSectionGetStorageSize(intFacetCounts, &numIntFacets);CHKERRQ(ierr);
1063   ierr = PetscSectionGetStorageSize(extFacetCounts, &numExtFacets);CHKERRQ(ierr);
1064   ierr = PetscMalloc1(numIntFacets, &intFacetsArray);CHKERRQ(ierr);
1065   ierr = PetscMalloc1(numIntFacets*2, &intFacetsToPatchCell);CHKERRQ(ierr);
1066   ierr = PetscMalloc1(numExtFacets, &extFacetsArray);CHKERRQ(ierr);
1067 
1068 
1069   /* Now that we know how much space we need, run through again and actually remember the cells. */
1070   for (v = vStart; v < vEnd; v++ ) {
1071     PetscHashIter hi;
1072     PetscInt       dof, off, cdof, coff, efdof, efoff, ifdof, ifoff, pdof, n = 0, cn = 0, ifn = 0, efn = 0;
1073 
1074     ierr = PetscSectionGetDof(pointCounts, v, &dof);CHKERRQ(ierr);
1075     ierr = PetscSectionGetOffset(pointCounts, v, &off);CHKERRQ(ierr);
1076     ierr = PetscSectionGetDof(cellCounts, v, &cdof);CHKERRQ(ierr);
1077     ierr = PetscSectionGetOffset(cellCounts, v, &coff);CHKERRQ(ierr);
1078     ierr = PetscSectionGetDof(intFacetCounts, v, &ifdof);CHKERRQ(ierr);
1079     ierr = PetscSectionGetOffset(intFacetCounts, v, &ifoff);CHKERRQ(ierr);
1080     ierr = PetscSectionGetDof(extFacetCounts, v, &efdof);CHKERRQ(ierr);
1081     ierr = PetscSectionGetOffset(extFacetCounts, v, &efoff);CHKERRQ(ierr);
1082     if (dof <= 0) continue;
1083     ierr = patch->patchconstructop((void *) patch, dm, v, ht);CHKERRQ(ierr);
1084     ierr = PCPatchCompleteCellPatch(pc, ht, cht);CHKERRQ(ierr);
1085     PetscHashIterBegin(cht, hi);
1086     while (!PetscHashIterAtEnd(cht, hi)) {
1087       PetscInt point;
1088 
1089       PetscHashIterGetKey(cht, hi, point);
1090       if (fStart <= point && point < fEnd) {
1091         const PetscInt *support;
1092         PetscInt supportSize, p;
1093         PetscBool interior = PETSC_TRUE;
1094         ierr = DMPlexGetSupport(dm, point, &support);CHKERRQ(ierr);
1095         ierr = DMPlexGetSupportSize(dm, point, &supportSize);CHKERRQ(ierr);
1096         if (supportSize == 1) {
1097           interior = PETSC_FALSE;
1098         } else {
1099           for (p = 0; p < supportSize; p++) {
1100             PetscBool found;
1101             /* FIXME: can I do this while iterating over cht? */
1102             PetscHSetIHas(cht, support[p], &found);
1103             if (!found) {
1104               interior = PETSC_FALSE;
1105               break;
1106             }
1107           }
1108         }
1109         if (interior) {
1110           intFacetsToPatchCell[2*(ifoff + ifn)] = support[0];
1111           intFacetsToPatchCell[2*(ifoff + ifn) + 1] = support[1];
1112           intFacetsArray[ifoff + ifn++] = point;
1113         } else {
1114           extFacetsArray[efoff + efn++] = point;
1115         }
1116       }
1117       ierr = PCPatchGetGlobalDofs(pc, patch->dofSection, -1, patch->combined, point, &pdof, NULL);CHKERRQ(ierr);
1118       if (pdof)                            {pointsArray[off + n++] = point;}
1119       if (point >= cStart && point < cEnd) {cellsArray[coff + cn++] = point;}
1120       PetscHashIterNext(cht, hi);
1121     }
1122     if (ifn != ifdof) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Number of interior facets in patch %D is %D, but should be %D", v, ifn, ifdof);
1123     if (efn != efdof) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Number of exterior facets in patch %D is %D, but should be %D", v, efn, efdof);
1124     if (cn != cdof) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Number of cells in patch %D is %D, but should be %D", v, cn, cdof);
1125     if (n  != dof)  SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Number of points in patch %D is %D, but should be %D", v, n, dof);
1126 
1127     for (ifn = 0; ifn < ifdof; ifn++) {
1128       PetscInt cell0 = intFacetsToPatchCell[2*(ifoff + ifn)];
1129       PetscInt cell1 = intFacetsToPatchCell[2*(ifoff + ifn) + 1];
1130       PetscBool found0 = PETSC_FALSE, found1 = PETSC_FALSE;
1131       for (n = 0; n < cdof; n++) {
1132         if (!found0 && cell0 == cellsArray[coff + n]) {
1133           intFacetsToPatchCell[2*(ifoff + ifn)] = n;
1134           found0 = PETSC_TRUE;
1135         }
1136         if (!found1 && cell1 == cellsArray[coff + n]) {
1137           intFacetsToPatchCell[2*(ifoff + ifn) + 1] = n;
1138           found1 = PETSC_TRUE;
1139         }
1140         if (found0 && found1) break;
1141       }
1142       if (!(found0 && found1)) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Didn't manage to find local point numbers for facet support");
1143     }
1144   }
1145   ierr = PetscHSetIDestroy(&ht);CHKERRQ(ierr);
1146   ierr = PetscHSetIDestroy(&cht);CHKERRQ(ierr);
1147   ierr = DMDestroy(&plex);CHKERRQ(ierr);
1148 
1149   ierr = ISCreateGeneral(PETSC_COMM_SELF, numCells,  cellsArray,  PETSC_OWN_POINTER, &patch->cells);CHKERRQ(ierr);
1150   ierr = PetscObjectSetName((PetscObject) patch->cells,  "Patch Cells");CHKERRQ(ierr);
1151   if (patch->viewCells) {
1152     ierr = ObjectView((PetscObject) patch->cellCounts, patch->viewerCells, patch->formatCells);CHKERRQ(ierr);
1153     ierr = ObjectView((PetscObject) patch->cells,      patch->viewerCells, patch->formatCells);CHKERRQ(ierr);
1154   }
1155   ierr = ISCreateGeneral(PETSC_COMM_SELF, numIntFacets,  intFacetsArray,  PETSC_OWN_POINTER, &patch->intFacets);CHKERRQ(ierr);
1156   ierr = PetscObjectSetName((PetscObject) patch->intFacets,  "Patch Interior Facets");CHKERRQ(ierr);
1157   ierr = ISCreateGeneral(PETSC_COMM_SELF, 2*numIntFacets, intFacetsToPatchCell, PETSC_OWN_POINTER, &patch->intFacetsToPatchCell);CHKERRQ(ierr);
1158   ierr = PetscObjectSetName((PetscObject) patch->intFacetsToPatchCell,  "Patch Interior Facets local support");CHKERRQ(ierr);
1159   if (patch->viewIntFacets) {
1160     ierr = ObjectView((PetscObject) patch->intFacetCounts,       patch->viewerIntFacets, patch->formatIntFacets);CHKERRQ(ierr);
1161     ierr = ObjectView((PetscObject) patch->intFacets,            patch->viewerIntFacets, patch->formatIntFacets);CHKERRQ(ierr);
1162     ierr = ObjectView((PetscObject) patch->intFacetsToPatchCell, patch->viewerIntFacets, patch->formatIntFacets);CHKERRQ(ierr);
1163   }
1164   ierr = ISCreateGeneral(PETSC_COMM_SELF, numExtFacets,  extFacetsArray,  PETSC_OWN_POINTER, &patch->extFacets);CHKERRQ(ierr);
1165   ierr = PetscObjectSetName((PetscObject) patch->extFacets,  "Patch Exterior Facets");CHKERRQ(ierr);
1166   if (patch->viewExtFacets) {
1167     ierr = ObjectView((PetscObject) patch->extFacetCounts, patch->viewerExtFacets, patch->formatExtFacets);CHKERRQ(ierr);
1168     ierr = ObjectView((PetscObject) patch->extFacets,      patch->viewerExtFacets, patch->formatExtFacets);CHKERRQ(ierr);
1169   }
1170   ierr = ISCreateGeneral(PETSC_COMM_SELF, numPoints, pointsArray, PETSC_OWN_POINTER, &patch->points);CHKERRQ(ierr);
1171   ierr = PetscObjectSetName((PetscObject) patch->points, "Patch Points");CHKERRQ(ierr);
1172   if (patch->viewPoints) {
1173     ierr = ObjectView((PetscObject) patch->pointCounts, patch->viewerPoints, patch->formatPoints);CHKERRQ(ierr);
1174     ierr = ObjectView((PetscObject) patch->points,      patch->viewerPoints, patch->formatPoints);CHKERRQ(ierr);
1175   }
1176   PetscFunctionReturn(0);
1177 }
1178 
1179 /*
1180  * PCPatchCreateCellPatchDiscretisationInfo - Build the dof maps for cell patches
1181  *
1182  * Input Parameters:
1183  * + dm - The DMPlex object defining the mesh
1184  * . cellCounts - Section with counts of cells around each vertex
1185  * . cells - IS of the cell point indices of cells in each patch
1186  * . cellNumbering - Section mapping plex cell points to Firedrake cell indices.
1187  * . nodesPerCell - number of nodes per cell.
1188  * - cellNodeMap - map from cells to node indices (nodesPerCell * numCells)
1189  *
1190  * Output Parameters:
1191  * + dofs - IS of local dof numbers of each cell in the patch, where local is a patch local numbering
1192  * . gtolCounts - Section with counts of dofs per cell patch
1193  * - gtol - IS mapping from global dofs to local dofs for each patch.
1194  */
1195 static PetscErrorCode PCPatchCreateCellPatchDiscretisationInfo(PC pc)
1196 {
1197   PC_PATCH       *patch           = (PC_PATCH *) pc->data;
1198   PetscSection    cellCounts      = patch->cellCounts;
1199   PetscSection    pointCounts     = patch->pointCounts;
1200   PetscSection    gtolCounts, gtolCountsWithArtificial = NULL, gtolCountsWithAll = NULL;
1201   IS              cells           = patch->cells;
1202   IS              points          = patch->points;
1203   PetscSection    cellNumbering   = patch->cellNumbering;
1204   PetscInt        Nf              = patch->nsubspaces;
1205   PetscInt        numCells, numPoints;
1206   PetscInt        numDofs;
1207   PetscInt        numGlobalDofs, numGlobalDofsWithArtificial, numGlobalDofsWithAll;
1208   PetscInt        totalDofsPerCell = patch->totalDofsPerCell;
1209   PetscInt        vStart, vEnd, v;
1210   const PetscInt *cellsArray, *pointsArray;
1211   PetscInt       *newCellsArray   = NULL;
1212   PetscInt       *dofsArray       = NULL;
1213   PetscInt       *dofsArrayWithArtificial = NULL;
1214   PetscInt       *dofsArrayWithAll = NULL;
1215   PetscInt       *offsArray       = NULL;
1216   PetscInt       *offsArrayWithArtificial = NULL;
1217   PetscInt       *offsArrayWithAll = NULL;
1218   PetscInt       *asmArray        = NULL;
1219   PetscInt       *asmArrayWithArtificial = NULL;
1220   PetscInt       *asmArrayWithAll = NULL;
1221   PetscInt       *globalDofsArray = NULL;
1222   PetscInt       *globalDofsArrayWithArtificial = NULL;
1223   PetscInt       *globalDofsArrayWithAll = NULL;
1224   PetscInt        globalIndex     = 0;
1225   PetscInt        key             = 0;
1226   PetscInt        asmKey          = 0;
1227   DM              dm              = NULL;
1228   const PetscInt *bcNodes         = NULL;
1229   PetscHMapI      ht;
1230   PetscHMapI      htWithArtificial;
1231   PetscHMapI      htWithAll;
1232   PetscHSetI      globalBcs;
1233   PetscInt        numBcs;
1234   PetscHSetI      ownedpts, seenpts, owneddofs, seendofs, artificialbcs;
1235   PetscInt        pStart, pEnd, p, i;
1236   char            option[PETSC_MAX_PATH_LEN];
1237   PetscBool       isNonlinear;
1238   PetscErrorCode  ierr;
1239 
1240   PetscFunctionBegin;
1241 
1242   ierr = PCGetDM(pc, &dm); CHKERRQ(ierr);
1243   /* dofcounts section is cellcounts section * dofPerCell */
1244   ierr = PetscSectionGetStorageSize(cellCounts, &numCells);CHKERRQ(ierr);
1245   ierr = PetscSectionGetStorageSize(patch->pointCounts, &numPoints);CHKERRQ(ierr);
1246   numDofs = numCells * totalDofsPerCell;
1247   ierr = PetscMalloc1(numDofs, &dofsArray);CHKERRQ(ierr);
1248   ierr = PetscMalloc1(numPoints*Nf, &offsArray);CHKERRQ(ierr);
1249   ierr = PetscMalloc1(numDofs, &asmArray);CHKERRQ(ierr);
1250   ierr = PetscMalloc1(numCells, &newCellsArray);CHKERRQ(ierr);
1251   ierr = PetscSectionGetChart(cellCounts, &vStart, &vEnd);CHKERRQ(ierr);
1252   ierr = PetscSectionCreate(PETSC_COMM_SELF, &patch->gtolCounts);CHKERRQ(ierr);
1253   gtolCounts = patch->gtolCounts;
1254   ierr = PetscSectionSetChart(gtolCounts, vStart, vEnd);CHKERRQ(ierr);
1255   ierr = PetscObjectSetName((PetscObject) patch->gtolCounts, "Patch Global Index Section");CHKERRQ(ierr);
1256 
1257   if(patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE)
1258   {
1259     ierr = PetscMalloc1(numPoints*Nf, &offsArrayWithArtificial);CHKERRQ(ierr);
1260     ierr = PetscMalloc1(numDofs, &asmArrayWithArtificial);CHKERRQ(ierr);
1261     ierr = PetscMalloc1(numDofs, &dofsArrayWithArtificial);CHKERRQ(ierr);
1262     ierr = PetscSectionCreate(PETSC_COMM_SELF, &patch->gtolCountsWithArtificial);CHKERRQ(ierr);
1263     gtolCountsWithArtificial = patch->gtolCountsWithArtificial;
1264     ierr = PetscSectionSetChart(gtolCountsWithArtificial, vStart, vEnd);CHKERRQ(ierr);
1265     ierr = PetscObjectSetName((PetscObject) patch->gtolCountsWithArtificial, "Patch Global Index Section Including Artificial BCs");CHKERRQ(ierr);
1266   }
1267 
1268   isNonlinear = patch->isNonlinear;
1269   if(isNonlinear)
1270   {
1271     ierr = PetscMalloc1(numPoints*Nf, &offsArrayWithAll);CHKERRQ(ierr);
1272     ierr = PetscMalloc1(numDofs, &asmArrayWithAll);CHKERRQ(ierr);
1273     ierr = PetscMalloc1(numDofs, &dofsArrayWithAll);CHKERRQ(ierr);
1274     ierr = PetscSectionCreate(PETSC_COMM_SELF, &patch->gtolCountsWithAll);CHKERRQ(ierr);
1275     gtolCountsWithAll = patch->gtolCountsWithAll;
1276     ierr = PetscSectionSetChart(gtolCountsWithAll, vStart, vEnd);CHKERRQ(ierr);
1277     ierr = PetscObjectSetName((PetscObject) patch->gtolCountsWithAll, "Patch Global Index Section Including All BCs");CHKERRQ(ierr);
1278   }
1279 
1280   /* Outside the patch loop, get the dofs that are globally-enforced Dirichlet
1281    conditions */
1282   ierr = PetscHSetICreate(&globalBcs);CHKERRQ(ierr);
1283   ierr = ISGetIndices(patch->ghostBcNodes, &bcNodes); CHKERRQ(ierr);
1284   ierr = ISGetSize(patch->ghostBcNodes, &numBcs); CHKERRQ(ierr);
1285   for (i = 0; i < numBcs; ++i) {
1286     ierr = PetscHSetIAdd(globalBcs, bcNodes[i]);CHKERRQ(ierr); /* these are already in concatenated numbering */
1287   }
1288   ierr = ISRestoreIndices(patch->ghostBcNodes, &bcNodes); CHKERRQ(ierr);
1289   ierr = ISDestroy(&patch->ghostBcNodes); CHKERRQ(ierr); /* memory optimisation */
1290 
1291   /* Hash tables for artificial BC construction */
1292   ierr = PetscHSetICreate(&ownedpts);CHKERRQ(ierr);
1293   ierr = PetscHSetICreate(&seenpts);CHKERRQ(ierr);
1294   ierr = PetscHSetICreate(&owneddofs);CHKERRQ(ierr);
1295   ierr = PetscHSetICreate(&seendofs);CHKERRQ(ierr);
1296   ierr = PetscHSetICreate(&artificialbcs);CHKERRQ(ierr);
1297 
1298   ierr = ISGetIndices(cells, &cellsArray);CHKERRQ(ierr);
1299   ierr = ISGetIndices(points, &pointsArray);CHKERRQ(ierr);
1300   ierr = PetscHMapICreate(&ht);CHKERRQ(ierr);
1301   ierr = PetscHMapICreate(&htWithArtificial);CHKERRQ(ierr);
1302   ierr = PetscHMapICreate(&htWithAll);CHKERRQ(ierr);
1303   for (v = vStart; v < vEnd; ++v) {
1304     PetscInt localIndex = 0;
1305     PetscInt localIndexWithArtificial = 0;
1306     PetscInt localIndexWithAll = 0;
1307     PetscInt dof, off, i, j, k, l;
1308 
1309     ierr = PetscHMapIClear(ht);CHKERRQ(ierr);
1310     ierr = PetscHMapIClear(htWithArtificial);CHKERRQ(ierr);
1311     ierr = PetscHMapIClear(htWithAll);CHKERRQ(ierr);
1312     ierr = PetscSectionGetDof(cellCounts, v, &dof);CHKERRQ(ierr);
1313     ierr = PetscSectionGetOffset(cellCounts, v, &off);CHKERRQ(ierr);
1314     if (dof <= 0) continue;
1315 
1316     /* Calculate the global numbers of the artificial BC dofs here first */
1317     ierr = patch->patchconstructop((void*)patch, dm, v, ownedpts); CHKERRQ(ierr);
1318     ierr = PCPatchCompleteCellPatch(pc, ownedpts, seenpts); CHKERRQ(ierr);
1319     ierr = PCPatchGetPointDofs(pc, ownedpts, owneddofs, v, &patch->subspaces_to_exclude); CHKERRQ(ierr);
1320     ierr = PCPatchGetPointDofs(pc, seenpts, seendofs, v, NULL); CHKERRQ(ierr);
1321     ierr = PCPatchComputeSetDifference_Private(owneddofs, seendofs, artificialbcs); CHKERRQ(ierr);
1322     if (patch->viewPatches) {
1323       PetscHSetI globalbcdofs;
1324       PetscHashIter hi;
1325       MPI_Comm comm = PetscObjectComm((PetscObject)pc);
1326 
1327       ierr = PetscHSetICreate(&globalbcdofs);CHKERRQ(ierr);
1328       ierr = PetscSynchronizedPrintf(comm, "Patch %d: owned dofs:\n", v); CHKERRQ(ierr);
1329       PetscHashIterBegin(owneddofs, hi);
1330       while (!PetscHashIterAtEnd(owneddofs, hi)) {
1331         PetscInt globalDof;
1332 
1333         PetscHashIterGetKey(owneddofs, hi, globalDof);
1334         PetscHashIterNext(owneddofs, hi);
1335         ierr = PetscSynchronizedPrintf(comm, "%d ", globalDof); CHKERRQ(ierr);
1336       }
1337       ierr = PetscSynchronizedPrintf(comm, "\n"); CHKERRQ(ierr);
1338       ierr = PetscSynchronizedPrintf(comm, "Patch %d: seen dofs:\n", v); CHKERRQ(ierr);
1339       PetscHashIterBegin(seendofs, hi);
1340       while (!PetscHashIterAtEnd(seendofs, hi)) {
1341         PetscInt globalDof;
1342         PetscBool flg;
1343 
1344         PetscHashIterGetKey(seendofs, hi, globalDof);
1345         PetscHashIterNext(seendofs, hi);
1346         ierr = PetscSynchronizedPrintf(comm, "%d ", globalDof); CHKERRQ(ierr);
1347 
1348         ierr = PetscHSetIHas(globalBcs, globalDof, &flg);CHKERRQ(ierr);
1349         if (flg) {ierr = PetscHSetIAdd(globalbcdofs, globalDof);CHKERRQ(ierr);}
1350       }
1351       ierr = PetscSynchronizedPrintf(comm, "\n"); CHKERRQ(ierr);
1352       ierr = PetscSynchronizedPrintf(comm, "Patch %d: global BCs:\n", v); CHKERRQ(ierr);
1353       ierr = PetscHSetIGetSize(globalbcdofs, &numBcs);CHKERRQ(ierr);
1354       if (numBcs > 0) {
1355         PetscHashIterBegin(globalbcdofs, hi);
1356         while (!PetscHashIterAtEnd(globalbcdofs, hi)) {
1357           PetscInt globalDof;
1358           PetscHashIterGetKey(globalbcdofs, hi, globalDof);
1359           PetscHashIterNext(globalbcdofs, hi);
1360           ierr = PetscSynchronizedPrintf(comm, "%d ", globalDof);CHKERRQ(ierr);
1361         }
1362       }
1363       ierr = PetscSynchronizedPrintf(comm, "\n");CHKERRQ(ierr);
1364       ierr = PetscSynchronizedPrintf(comm, "Patch %d: artificial BCs:\n", v);CHKERRQ(ierr);
1365       ierr = PetscHSetIGetSize(artificialbcs, &numBcs);CHKERRQ(ierr);
1366       if (numBcs > 0) {
1367         PetscHashIterBegin(artificialbcs, hi);
1368         while (!PetscHashIterAtEnd(artificialbcs, hi)) {
1369           PetscInt globalDof;
1370           PetscHashIterGetKey(artificialbcs, hi, globalDof);
1371           PetscHashIterNext(artificialbcs, hi);
1372           ierr = PetscSynchronizedPrintf(comm, "%d ", globalDof); CHKERRQ(ierr);
1373         }
1374       }
1375       ierr = PetscSynchronizedPrintf(comm, "\n\n"); CHKERRQ(ierr);
1376       ierr = PetscHSetIDestroy(&globalbcdofs);CHKERRQ(ierr);
1377     }
1378    for (k = 0; k < patch->nsubspaces; ++k) {
1379       const PetscInt *cellNodeMap    = patch->cellNodeMap[k];
1380       PetscInt        nodesPerCell   = patch->nodesPerCell[k];
1381       PetscInt        subspaceOffset = patch->subspaceOffsets[k];
1382       PetscInt        bs             = patch->bs[k];
1383 
1384       for (i = off; i < off + dof; ++i) {
1385         /* Walk over the cells in this patch. */
1386         const PetscInt c    = cellsArray[i];
1387         PetscInt       cell = c;
1388 
1389         /* TODO Change this to an IS */
1390         if (cellNumbering) {
1391           ierr = PetscSectionGetDof(cellNumbering, c, &cell);CHKERRQ(ierr);
1392           if (cell <= 0) SETERRQ1(PetscObjectComm((PetscObject) pc), PETSC_ERR_ARG_OUTOFRANGE, "Cell %D doesn't appear in cell numbering map", c);
1393           ierr = PetscSectionGetOffset(cellNumbering, c, &cell);CHKERRQ(ierr);
1394         }
1395         newCellsArray[i] = cell;
1396         for (j = 0; j < nodesPerCell; ++j) {
1397           /* For each global dof, map it into contiguous local storage. */
1398           const PetscInt globalDof = cellNodeMap[cell*nodesPerCell + j]*bs + subspaceOffset;
1399           /* finally, loop over block size */
1400           for (l = 0; l < bs; ++l) {
1401             PetscInt  localDof;
1402             PetscBool isGlobalBcDof, isArtificialBcDof;
1403 
1404             /* first, check if this is either a globally enforced or locally enforced BC dof */
1405             ierr = PetscHSetIHas(globalBcs, globalDof + l, &isGlobalBcDof);CHKERRQ(ierr);
1406             ierr = PetscHSetIHas(artificialbcs, globalDof + l, &isArtificialBcDof);CHKERRQ(ierr);
1407 
1408             /* if it's either, don't ever give it a local dof number */
1409             if (isGlobalBcDof || isArtificialBcDof) {
1410               dofsArray[globalIndex] = -1; /* don't use this in assembly in this patch */
1411             } else {
1412               ierr = PetscHMapIGet(ht, globalDof + l, &localDof);CHKERRQ(ierr);
1413               if (localDof == -1) {
1414                 localDof = localIndex++;
1415                 ierr = PetscHMapISet(ht, globalDof + l, localDof);CHKERRQ(ierr);
1416               }
1417               if ( globalIndex >= numDofs ) SETERRQ2(PETSC_COMM_WORLD, PETSC_ERR_ARG_OUTOFRANGE, "Found more dofs %D than expected %D", globalIndex+1, numDofs);
1418               /* And store. */
1419               dofsArray[globalIndex] = localDof;
1420             }
1421 
1422             if(patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
1423               if (isGlobalBcDof) {
1424                 dofsArrayWithArtificial[globalIndex] = -1; /* don't use this in assembly in this patch */
1425               } else {
1426                 ierr = PetscHMapIGet(htWithArtificial, globalDof + l, &localDof);CHKERRQ(ierr);
1427                 if (localDof == -1) {
1428                   localDof = localIndexWithArtificial++;
1429                   ierr = PetscHMapISet(htWithArtificial, globalDof + l, localDof);CHKERRQ(ierr);
1430                 }
1431                 if ( globalIndex >= numDofs ) SETERRQ2(PETSC_COMM_WORLD, PETSC_ERR_ARG_OUTOFRANGE, "Found more dofs %D than expected %D", globalIndex+1, numDofs);
1432                 /* And store.*/
1433                 dofsArrayWithArtificial[globalIndex] = localDof;
1434               }
1435             }
1436 
1437             if(isNonlinear) {
1438               /* Build the dofmap for the function space with _all_ dofs,
1439                  including those in any kind of boundary condition */
1440               ierr = PetscHMapIGet(htWithAll, globalDof + l, &localDof);CHKERRQ(ierr);
1441               if (localDof == -1) {
1442                 localDof = localIndexWithAll++;
1443                 ierr = PetscHMapISet(htWithAll, globalDof + l, localDof);CHKERRQ(ierr);
1444               }
1445               if ( globalIndex >= numDofs ) SETERRQ2(PETSC_COMM_WORLD, PETSC_ERR_ARG_OUTOFRANGE, "Found more dofs %D than expected %D", globalIndex+1, numDofs);
1446               /* And store.*/
1447               dofsArrayWithAll[globalIndex] = localDof;
1448             }
1449             globalIndex++;
1450           }
1451         }
1452       }
1453     }
1454      /*How many local dofs in this patch? */
1455    if (patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
1456      ierr = PetscHMapIGetSize(htWithArtificial, &dof);CHKERRQ(ierr);
1457      ierr = PetscSectionSetDof(gtolCountsWithArtificial, v, dof);CHKERRQ(ierr);
1458    }
1459    if (isNonlinear) {
1460      ierr = PetscHMapIGetSize(htWithAll, &dof);CHKERRQ(ierr);
1461      ierr = PetscSectionSetDof(gtolCountsWithAll, v, dof);CHKERRQ(ierr);
1462    }
1463     ierr = PetscHMapIGetSize(ht, &dof);CHKERRQ(ierr);
1464     ierr = PetscSectionSetDof(gtolCounts, v, dof);CHKERRQ(ierr);
1465   }
1466   if (globalIndex != numDofs) SETERRQ2(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Expected number of dofs (%d) doesn't match found number (%d)", numDofs, globalIndex);
1467   ierr = PetscSectionSetUp(gtolCounts);CHKERRQ(ierr);
1468   ierr = PetscSectionGetStorageSize(gtolCounts, &numGlobalDofs);CHKERRQ(ierr);
1469   ierr = PetscMalloc1(numGlobalDofs, &globalDofsArray);CHKERRQ(ierr);
1470 
1471   if (patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
1472     ierr = PetscSectionSetUp(gtolCountsWithArtificial);CHKERRQ(ierr);
1473     ierr = PetscSectionGetStorageSize(gtolCountsWithArtificial, &numGlobalDofsWithArtificial);CHKERRQ(ierr);
1474     ierr = PetscMalloc1(numGlobalDofsWithArtificial, &globalDofsArrayWithArtificial);CHKERRQ(ierr);
1475   }
1476   if (isNonlinear) {
1477     ierr = PetscSectionSetUp(gtolCountsWithAll);CHKERRQ(ierr);
1478     ierr = PetscSectionGetStorageSize(gtolCountsWithAll, &numGlobalDofsWithAll);CHKERRQ(ierr);
1479     ierr = PetscMalloc1(numGlobalDofsWithAll, &globalDofsArrayWithAll);CHKERRQ(ierr);
1480   }
1481   /* Now populate the global to local map.  This could be merged into the above loop if we were willing to deal with reallocs. */
1482   for (v = vStart; v < vEnd; ++v) {
1483     PetscHashIter hi;
1484     PetscInt      dof, off, Np, ooff, i, j, k, l;
1485 
1486     ierr = PetscHMapIClear(ht);CHKERRQ(ierr);
1487     ierr = PetscHMapIClear(htWithArtificial);CHKERRQ(ierr);
1488     ierr = PetscHMapIClear(htWithAll);CHKERRQ(ierr);
1489     ierr = PetscSectionGetDof(cellCounts, v, &dof);CHKERRQ(ierr);
1490     ierr = PetscSectionGetOffset(cellCounts, v, &off);CHKERRQ(ierr);
1491     ierr = PetscSectionGetDof(pointCounts, v, &Np);CHKERRQ(ierr);
1492     ierr = PetscSectionGetOffset(pointCounts, v, &ooff);CHKERRQ(ierr);
1493     if (dof <= 0) continue;
1494 
1495     for (k = 0; k < patch->nsubspaces; ++k) {
1496       const PetscInt *cellNodeMap    = patch->cellNodeMap[k];
1497       PetscInt        nodesPerCell   = patch->nodesPerCell[k];
1498       PetscInt        subspaceOffset = patch->subspaceOffsets[k];
1499       PetscInt        bs             = patch->bs[k];
1500       PetscInt        goff;
1501 
1502       for (i = off; i < off + dof; ++i) {
1503         /* Reconstruct mapping of global-to-local on this patch. */
1504         const PetscInt c    = cellsArray[i];
1505         PetscInt       cell = c;
1506 
1507         if (cellNumbering) {ierr = PetscSectionGetOffset(cellNumbering, c, &cell);CHKERRQ(ierr);}
1508         for (j = 0; j < nodesPerCell; ++j) {
1509           for (l = 0; l < bs; ++l) {
1510             const PetscInt globalDof = cellNodeMap[cell*nodesPerCell + j]*bs + l + subspaceOffset;
1511             const PetscInt localDof  = dofsArray[key];
1512             if (localDof >= 0) {ierr = PetscHMapISet(ht, globalDof, localDof);CHKERRQ(ierr);}
1513             if (patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
1514               const PetscInt localDofWithArtificial = dofsArrayWithArtificial[key];
1515               if (localDofWithArtificial >= 0) {
1516                 ierr = PetscHMapISet(htWithArtificial, globalDof, localDofWithArtificial);CHKERRQ(ierr);
1517               }
1518             }
1519             if (isNonlinear) {
1520               const PetscInt localDofWithAll = dofsArrayWithAll[key];
1521               if (localDofWithAll >= 0) {
1522                 ierr = PetscHMapISet(htWithAll, globalDof, localDofWithAll);CHKERRQ(ierr);
1523               }
1524             }
1525             key++;
1526           }
1527         }
1528       }
1529 
1530       /* Shove it in the output data structure. */
1531       ierr = PetscSectionGetOffset(gtolCounts, v, &goff);CHKERRQ(ierr);
1532       PetscHashIterBegin(ht, hi);
1533       while (!PetscHashIterAtEnd(ht, hi)) {
1534         PetscInt globalDof, localDof;
1535 
1536         PetscHashIterGetKey(ht, hi, globalDof);
1537         PetscHashIterGetVal(ht, hi, localDof);
1538         if (globalDof >= 0) globalDofsArray[goff + localDof] = globalDof;
1539         PetscHashIterNext(ht, hi);
1540       }
1541 
1542       if (patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
1543         ierr = PetscSectionGetOffset(gtolCountsWithArtificial, v, &goff);CHKERRQ(ierr);
1544         PetscHashIterBegin(htWithArtificial, hi);
1545         while (!PetscHashIterAtEnd(htWithArtificial, hi)) {
1546           PetscInt globalDof, localDof;
1547           PetscHashIterGetKey(htWithArtificial, hi, globalDof);
1548           PetscHashIterGetVal(htWithArtificial, hi, localDof);
1549           if (globalDof >= 0) globalDofsArrayWithArtificial[goff + localDof] = globalDof;
1550           PetscHashIterNext(htWithArtificial, hi);
1551         }
1552       }
1553       if (isNonlinear) {
1554         ierr = PetscSectionGetOffset(gtolCountsWithAll, v, &goff);CHKERRQ(ierr);
1555         PetscHashIterBegin(htWithAll, hi);
1556         while (!PetscHashIterAtEnd(htWithAll, hi)) {
1557           PetscInt globalDof, localDof;
1558           PetscHashIterGetKey(htWithAll, hi, globalDof);
1559           PetscHashIterGetVal(htWithAll, hi, localDof);
1560           if (globalDof >= 0) globalDofsArrayWithAll[goff + localDof] = globalDof;
1561           PetscHashIterNext(htWithAll, hi);
1562         }
1563       }
1564 
1565       for (p = 0; p < Np; ++p) {
1566         const PetscInt point = pointsArray[ooff + p];
1567         PetscInt       globalDof, localDof;
1568 
1569         ierr = PCPatchGetGlobalDofs(pc, patch->dofSection, k, patch->combined, point, NULL, &globalDof);CHKERRQ(ierr);
1570         ierr = PetscHMapIGet(ht, globalDof, &localDof);CHKERRQ(ierr);
1571         offsArray[(ooff + p)*Nf + k] = localDof;
1572         if (patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
1573           ierr = PetscHMapIGet(htWithArtificial, globalDof, &localDof);CHKERRQ(ierr);
1574           offsArrayWithArtificial[(ooff + p)*Nf + k] = localDof;
1575         }
1576         if (isNonlinear) {
1577           ierr = PetscHMapIGet(htWithAll, globalDof, &localDof);CHKERRQ(ierr);
1578           offsArrayWithAll[(ooff + p)*Nf + k] = localDof;
1579         }
1580       }
1581     }
1582 
1583     ierr = PetscHSetIDestroy(&globalBcs);CHKERRQ(ierr);
1584     ierr = PetscHSetIDestroy(&ownedpts);CHKERRQ(ierr);
1585     ierr = PetscHSetIDestroy(&seenpts);CHKERRQ(ierr);
1586     ierr = PetscHSetIDestroy(&owneddofs);CHKERRQ(ierr);
1587     ierr = PetscHSetIDestroy(&seendofs);CHKERRQ(ierr);
1588     ierr = PetscHSetIDestroy(&artificialbcs);CHKERRQ(ierr);
1589 
1590       /* At this point, we have a hash table ht built that maps globalDof -> localDof.
1591      We need to create the dof table laid out cellwise first, then by subspace,
1592      as the assembler assembles cell-wise and we need to stuff the different
1593      contributions of the different function spaces to the right places. So we loop
1594      over cells, then over subspaces. */
1595     if (patch->nsubspaces > 1) { /* for nsubspaces = 1, data we need is already in dofsArray */
1596       for (i = off; i < off + dof; ++i) {
1597         const PetscInt c    = cellsArray[i];
1598         PetscInt       cell = c;
1599 
1600         if (cellNumbering) {ierr = PetscSectionGetOffset(cellNumbering, c, &cell);CHKERRQ(ierr);}
1601         for (k = 0; k < patch->nsubspaces; ++k) {
1602           const PetscInt *cellNodeMap    = patch->cellNodeMap[k];
1603           PetscInt        nodesPerCell   = patch->nodesPerCell[k];
1604           PetscInt        subspaceOffset = patch->subspaceOffsets[k];
1605           PetscInt        bs             = patch->bs[k];
1606 
1607           for (j = 0; j < nodesPerCell; ++j) {
1608             for (l = 0; l < bs; ++l) {
1609               const PetscInt globalDof = cellNodeMap[cell*nodesPerCell + j]*bs + l + subspaceOffset;
1610               PetscInt       localDof;
1611 
1612               ierr = PetscHMapIGet(ht, globalDof, &localDof);CHKERRQ(ierr);
1613               /* If it's not in the hash table, i.e. is a BC dof,
1614                then the PetscHSetIMap above gives -1, which matches
1615                exactly the convention for PETSc's matrix assembly to
1616                ignore the dof. So we don't need to do anything here */
1617               asmArray[asmKey] = localDof;
1618               if (patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
1619                 ierr = PetscHMapIGet(htWithArtificial, globalDof, &localDof);CHKERRQ(ierr);
1620                 asmArrayWithArtificial[asmKey] = localDof;
1621               }
1622               if (isNonlinear) {
1623                 ierr = PetscHMapIGet(htWithAll, globalDof, &localDof);CHKERRQ(ierr);
1624                 asmArrayWithAll[asmKey] = localDof;
1625               }
1626               asmKey++;
1627             }
1628           }
1629         }
1630       }
1631     }
1632   }
1633   if (1 == patch->nsubspaces) {
1634     ierr = PetscMemcpy(asmArray, dofsArray, numDofs * sizeof(PetscInt));CHKERRQ(ierr);
1635     if (patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
1636       ierr = PetscMemcpy(asmArrayWithArtificial, dofsArrayWithArtificial, numDofs * sizeof(PetscInt));CHKERRQ(ierr);
1637     }
1638     if (isNonlinear) {
1639       ierr = PetscMemcpy(asmArrayWithAll, dofsArrayWithAll, numDofs * sizeof(PetscInt));CHKERRQ(ierr);
1640     }
1641   }
1642 
1643   ierr = PetscHMapIDestroy(&ht);CHKERRQ(ierr);
1644   ierr = PetscHMapIDestroy(&htWithArtificial);CHKERRQ(ierr);
1645   ierr = PetscHMapIDestroy(&htWithAll);CHKERRQ(ierr);
1646   ierr = ISRestoreIndices(cells, &cellsArray);CHKERRQ(ierr);
1647   ierr = ISRestoreIndices(points, &pointsArray);CHKERRQ(ierr);
1648   ierr = PetscFree(dofsArray);CHKERRQ(ierr);
1649   if (patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
1650     ierr = PetscFree(dofsArrayWithArtificial);CHKERRQ(ierr);
1651   }
1652   if (isNonlinear) {
1653     ierr = PetscFree(dofsArrayWithAll);CHKERRQ(ierr);
1654   }
1655   /* Create placeholder section for map from points to patch dofs */
1656   ierr = PetscSectionCreate(PETSC_COMM_SELF, &patch->patchSection);CHKERRQ(ierr);
1657   ierr = PetscSectionSetNumFields(patch->patchSection, patch->nsubspaces);CHKERRQ(ierr);
1658   if (patch->combined) {
1659     PetscInt numFields;
1660     ierr = PetscSectionGetNumFields(patch->dofSection[0], &numFields);CHKERRQ(ierr);
1661     if (numFields != patch->nsubspaces) SETERRQ2(PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONG, "Mismatch between number of section fields %D and number of subspaces %D", numFields, patch->nsubspaces);
1662     ierr = PetscSectionGetChart(patch->dofSection[0], &pStart, &pEnd);CHKERRQ(ierr);
1663     ierr = PetscSectionSetChart(patch->patchSection, pStart, pEnd);CHKERRQ(ierr);
1664     for (p = pStart; p < pEnd; ++p) {
1665       PetscInt dof, fdof, f;
1666 
1667       ierr = PetscSectionGetDof(patch->dofSection[0], p, &dof);CHKERRQ(ierr);
1668       ierr = PetscSectionSetDof(patch->patchSection, p, dof);CHKERRQ(ierr);
1669       for (f = 0; f < patch->nsubspaces; ++f) {
1670         ierr = PetscSectionGetFieldDof(patch->dofSection[0], p, f, &fdof);CHKERRQ(ierr);
1671         ierr = PetscSectionSetFieldDof(patch->patchSection, p, f, fdof);CHKERRQ(ierr);
1672       }
1673     }
1674   } else {
1675     PetscInt pStartf, pEndf, f;
1676     pStart = PETSC_MAX_INT;
1677     pEnd = PETSC_MIN_INT;
1678     for (f = 0; f < patch->nsubspaces; ++f) {
1679       ierr = PetscSectionGetChart(patch->dofSection[f], &pStartf, &pEndf);CHKERRQ(ierr);
1680       pStart = PetscMin(pStart, pStartf);
1681       pEnd = PetscMax(pEnd, pEndf);
1682     }
1683     ierr = PetscSectionSetChart(patch->patchSection, pStart, pEnd);CHKERRQ(ierr);
1684     for (f = 0; f < patch->nsubspaces; ++f) {
1685       ierr = PetscSectionGetChart(patch->dofSection[f], &pStartf, &pEndf);CHKERRQ(ierr);
1686       for (p = pStartf; p < pEndf; ++p) {
1687         PetscInt fdof;
1688         ierr = PetscSectionGetDof(patch->dofSection[f], p, &fdof);CHKERRQ(ierr);
1689         ierr = PetscSectionAddDof(patch->patchSection, p, fdof);CHKERRQ(ierr);
1690         ierr = PetscSectionSetFieldDof(patch->patchSection, p, f, fdof);CHKERRQ(ierr);
1691       }
1692     }
1693   }
1694   ierr = PetscSectionSetUp(patch->patchSection);CHKERRQ(ierr);
1695   ierr = PetscSectionSetUseFieldOffsets(patch->patchSection, PETSC_TRUE);CHKERRQ(ierr);
1696   /* Replace cell indices with firedrake-numbered ones. */
1697   ierr = ISGeneralSetIndices(cells, numCells, (const PetscInt *) newCellsArray, PETSC_OWN_POINTER);CHKERRQ(ierr);
1698   ierr = ISCreateGeneral(PETSC_COMM_SELF, numGlobalDofs, globalDofsArray, PETSC_OWN_POINTER, &patch->gtol);CHKERRQ(ierr);
1699   ierr = PetscObjectSetName((PetscObject) patch->gtol, "Global Indices");CHKERRQ(ierr);
1700   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_g2l_view", patch->classname);CHKERRQ(ierr);
1701   ierr = PetscSectionViewFromOptions(patch->gtolCounts, (PetscObject) pc, option);CHKERRQ(ierr);
1702   ierr = ISViewFromOptions(patch->gtol, (PetscObject) pc, option);CHKERRQ(ierr);
1703   ierr = ISCreateGeneral(PETSC_COMM_SELF, numDofs, asmArray, PETSC_OWN_POINTER, &patch->dofs);CHKERRQ(ierr);
1704   ierr = ISCreateGeneral(PETSC_COMM_SELF, numPoints*Nf, offsArray, PETSC_OWN_POINTER, &patch->offs);CHKERRQ(ierr);
1705   if (patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
1706     ierr = ISCreateGeneral(PETSC_COMM_SELF, numGlobalDofsWithArtificial, globalDofsArrayWithArtificial, PETSC_OWN_POINTER, &patch->gtolWithArtificial);CHKERRQ(ierr);
1707     ierr = ISCreateGeneral(PETSC_COMM_SELF, numDofs, asmArrayWithArtificial, PETSC_OWN_POINTER, &patch->dofsWithArtificial);CHKERRQ(ierr);
1708     ierr = ISCreateGeneral(PETSC_COMM_SELF, numPoints*Nf, offsArrayWithArtificial, PETSC_OWN_POINTER, &patch->offsWithArtificial);CHKERRQ(ierr);
1709   }
1710   if (isNonlinear) {
1711     ierr = ISCreateGeneral(PETSC_COMM_SELF, numGlobalDofsWithAll, globalDofsArrayWithAll, PETSC_OWN_POINTER, &patch->gtolWithAll);CHKERRQ(ierr);
1712     ierr = ISCreateGeneral(PETSC_COMM_SELF, numDofs, asmArrayWithAll, PETSC_OWN_POINTER, &patch->dofsWithAll);CHKERRQ(ierr);
1713     ierr = ISCreateGeneral(PETSC_COMM_SELF, numPoints*Nf, offsArrayWithAll, PETSC_OWN_POINTER, &patch->offsWithAll);CHKERRQ(ierr);
1714   }
1715   PetscFunctionReturn(0);
1716 }
1717 
1718 static PetscErrorCode PCPatchCreateMatrix_Private(PC pc, PetscInt point, Mat *mat, PetscBool withArtificial)
1719 {
1720   PC_PATCH      *patch = (PC_PATCH *) pc->data;
1721   Vec            x, y;
1722   PetscBool      flg;
1723   PetscInt       csize, rsize;
1724   const char    *prefix = NULL;
1725   PetscErrorCode ierr;
1726 
1727   PetscFunctionBegin;
1728   if(withArtificial) {
1729     /* would be nice if we could create a rectangular matrix of size numDofsWithArtificial x numDofs here */
1730     x = patch->patchRHSWithArtificial[point];
1731     y = patch->patchRHSWithArtificial[point];
1732   } else {
1733     x = patch->patchRHS[point];
1734     y = patch->patchUpdate[point];
1735   }
1736 
1737   ierr = VecGetSize(x, &csize);CHKERRQ(ierr);
1738   ierr = VecGetSize(y, &rsize);CHKERRQ(ierr);
1739   ierr = MatCreate(PETSC_COMM_SELF, mat);CHKERRQ(ierr);
1740   ierr = PCGetOptionsPrefix(pc, &prefix);CHKERRQ(ierr);
1741   ierr = MatSetOptionsPrefix(*mat, prefix);CHKERRQ(ierr);
1742   ierr = MatAppendOptionsPrefix(*mat, "pc_patch_sub_");CHKERRQ(ierr);
1743   if (patch->sub_mat_type)       {ierr = MatSetType(*mat, patch->sub_mat_type);CHKERRQ(ierr);}
1744   else if (!patch->sub_mat_type) {ierr = MatSetType(*mat, MATDENSE);CHKERRQ(ierr);}
1745   ierr = MatSetSizes(*mat, rsize, csize, rsize, csize);CHKERRQ(ierr);
1746   ierr = PetscObjectTypeCompare((PetscObject) *mat, MATDENSE, &flg);CHKERRQ(ierr);
1747   if (!flg) {ierr = PetscObjectTypeCompare((PetscObject)*mat, MATSEQDENSE, &flg);CHKERRQ(ierr);}
1748   /* Sparse patch matrices */
1749   if (!flg) {
1750     PetscBT         bt;
1751     PetscInt       *dnnz      = NULL;
1752     const PetscInt *dofsArray = NULL;
1753     PetscInt        pStart, pEnd, ncell, offset, c, i, j;
1754 
1755     if(withArtificial) {
1756       ierr = ISGetIndices(patch->dofsWithArtificial, &dofsArray);CHKERRQ(ierr);
1757     } else {
1758       ierr = ISGetIndices(patch->dofs, &dofsArray);CHKERRQ(ierr);
1759     }
1760     ierr = PetscSectionGetChart(patch->cellCounts, &pStart, &pEnd);CHKERRQ(ierr);
1761     point += pStart;
1762     if (point >= pEnd) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Operator point %D not in [%D, %D)\n", point, pStart, pEnd);CHKERRQ(ierr);
1763     ierr = PetscSectionGetDof(patch->cellCounts, point, &ncell);CHKERRQ(ierr);
1764     ierr = PetscSectionGetOffset(patch->cellCounts, point, &offset);CHKERRQ(ierr);
1765     ierr = PetscLogEventBegin(PC_Patch_Prealloc, pc, 0, 0, 0);CHKERRQ(ierr);
1766     /* A PetscBT uses N^2 bits to store the sparsity pattern on a
1767      * patch. This is probably OK if the patches are not too big,
1768      * but uses too much memory. We therefore switch based on rsize. */
1769     if (rsize < 3000) { /* FIXME: I picked this switch value out of my hat */
1770       PetscScalar *zeroes;
1771       PetscInt rows;
1772 
1773       ierr = PetscCalloc1(rsize, &dnnz);CHKERRQ(ierr);
1774       ierr = PetscBTCreate(rsize*rsize, &bt);CHKERRQ(ierr);
1775       for (c = 0; c < ncell; ++c) {
1776         const PetscInt *idx = dofsArray + (offset + c)*patch->totalDofsPerCell;
1777         for (i = 0; i < patch->totalDofsPerCell; ++i) {
1778           const PetscInt row = idx[i];
1779           if (row < 0) continue;
1780           for (j = 0; j < patch->totalDofsPerCell; ++j) {
1781             const PetscInt col = idx[j];
1782             const PetscInt key = row*rsize + col;
1783             if (col < 0) continue;
1784             if (!PetscBTLookupSet(bt, key)) ++dnnz[row];
1785           }
1786         }
1787       }
1788 
1789       if (patch->usercomputeopintfacet) {
1790         const PetscInt *intFacetsArray = NULL;
1791         PetscInt        i, numIntFacets, intFacetOffset;
1792         const PetscInt *facetCells = NULL;
1793 
1794         ierr = PetscSectionGetDof(patch->intFacetCounts, point, &numIntFacets);CHKERRQ(ierr);
1795         ierr = PetscSectionGetOffset(patch->intFacetCounts, point, &intFacetOffset);CHKERRQ(ierr);
1796         ierr = ISGetIndices(patch->intFacetsToPatchCell, &facetCells);CHKERRQ(ierr);
1797         ierr = ISGetIndices(patch->intFacets, &intFacetsArray);CHKERRQ(ierr);
1798         for (i = 0; i < numIntFacets; i++) {
1799           const PetscInt cell0 = facetCells[2*(intFacetOffset + i) + 0];
1800           const PetscInt cell1 = facetCells[2*(intFacetOffset + i) + 1];
1801           PetscInt       celli, cellj;
1802 
1803           for (celli = 0; celli < patch->totalDofsPerCell; celli++) {
1804             const PetscInt row = dofsArray[(offset + cell0)*patch->totalDofsPerCell + celli];
1805             if (row < 0) continue;
1806             for (cellj = 0; cellj < patch->totalDofsPerCell; cellj++) {
1807               const PetscInt col = dofsArray[(offset + cell1)*patch->totalDofsPerCell + cellj];
1808               const PetscInt key = row*rsize + col;
1809               if (col < 0) continue;
1810               if (!PetscBTLookupSet(bt, key)) ++dnnz[row];
1811             }
1812           }
1813 
1814           for (celli = 0; celli < patch->totalDofsPerCell; celli++) {
1815             const PetscInt row = dofsArray[(offset + cell1)*patch->totalDofsPerCell + celli];
1816             if (row < 0) continue;
1817             for (cellj = 0; cellj < patch->totalDofsPerCell; cellj++) {
1818               const PetscInt col = dofsArray[(offset + cell0)*patch->totalDofsPerCell + cellj];
1819               const PetscInt key = row*rsize + col;
1820               if (col < 0) continue;
1821               if (!PetscBTLookupSet(bt, key)) ++dnnz[row];
1822             }
1823           }
1824         }
1825       }
1826       ierr = PetscBTDestroy(&bt);CHKERRQ(ierr);
1827       ierr = MatXAIJSetPreallocation(*mat, 1, dnnz, NULL, NULL, NULL);CHKERRQ(ierr);
1828       ierr = PetscFree(dnnz);CHKERRQ(ierr);
1829 
1830       ierr = PetscCalloc1(patch->totalDofsPerCell*patch->totalDofsPerCell, &zeroes);CHKERRQ(ierr);
1831       for (c = 0; c < ncell; ++c) {
1832         const PetscInt *idx = &dofsArray[(offset + c)*patch->totalDofsPerCell];
1833         ierr = MatSetValues(*mat, patch->totalDofsPerCell, idx, patch->totalDofsPerCell, idx, zeroes, INSERT_VALUES);CHKERRQ(ierr);
1834       }
1835       ierr = MatGetLocalSize(*mat, &rows, NULL);CHKERRQ(ierr);
1836       for (i = 0; i < rows; ++i) {
1837         ierr = MatSetValues(*mat, 1, &i, 1, &i, zeroes, INSERT_VALUES);CHKERRQ(ierr);
1838       }
1839 
1840       if (patch->usercomputeopintfacet) {
1841         const PetscInt *intFacetsArray = NULL;
1842         PetscInt i, numIntFacets, intFacetOffset;
1843         const PetscInt *facetCells = NULL;
1844 
1845         ierr = PetscSectionGetDof(patch->intFacetCounts, point, &numIntFacets);CHKERRQ(ierr);
1846         ierr = PetscSectionGetOffset(patch->intFacetCounts, point, &intFacetOffset);CHKERRQ(ierr);
1847         ierr = ISGetIndices(patch->intFacetsToPatchCell, &facetCells);CHKERRQ(ierr);
1848         ierr = ISGetIndices(patch->intFacets, &intFacetsArray);CHKERRQ(ierr);
1849         for (i = 0; i < numIntFacets; i++) {
1850           const PetscInt cell0 = facetCells[2*(intFacetOffset + i) + 0];
1851           const PetscInt cell1 = facetCells[2*(intFacetOffset + i) + 1];
1852           const PetscInt *cell0idx = &dofsArray[(offset + cell0)*patch->totalDofsPerCell];
1853           const PetscInt *cell1idx = &dofsArray[(offset + cell1)*patch->totalDofsPerCell];
1854           ierr = MatSetValues(*mat, patch->totalDofsPerCell, cell0idx, patch->totalDofsPerCell, cell1idx, zeroes, INSERT_VALUES);CHKERRQ(ierr);
1855           ierr = MatSetValues(*mat, patch->totalDofsPerCell, cell1idx, patch->totalDofsPerCell, cell0idx, zeroes, INSERT_VALUES);CHKERRQ(ierr);
1856         }
1857       }
1858 
1859       ierr = MatAssemblyBegin(*mat, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1860       ierr = MatAssemblyEnd(*mat, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1861 
1862       ierr = PetscFree(zeroes);CHKERRQ(ierr);
1863 
1864     } else { /* rsize too big, use MATPREALLOCATOR */
1865       Mat preallocator;
1866       PetscScalar* vals;
1867 
1868       ierr = PetscCalloc1(patch->totalDofsPerCell*patch->totalDofsPerCell, &vals);CHKERRQ(ierr);
1869       ierr = MatCreate(PETSC_COMM_SELF, &preallocator);CHKERRQ(ierr);
1870       ierr = MatSetType(preallocator, MATPREALLOCATOR);CHKERRQ(ierr);
1871       ierr = MatSetSizes(preallocator, rsize, rsize, rsize, rsize);CHKERRQ(ierr);
1872       ierr = MatSetUp(preallocator);CHKERRQ(ierr);
1873 
1874       for (c = 0; c < ncell; ++c) {
1875         const PetscInt *idx = dofsArray + (offset + c)*patch->totalDofsPerCell;
1876         ierr = MatSetValues(preallocator, patch->totalDofsPerCell, idx, patch->totalDofsPerCell, idx, vals, INSERT_VALUES);CHKERRQ(ierr);
1877       }
1878 
1879       if (patch->usercomputeopintfacet) {
1880         const PetscInt *intFacetsArray = NULL;
1881         PetscInt        i, numIntFacets, intFacetOffset;
1882         const PetscInt *facetCells = NULL;
1883 
1884         ierr = PetscSectionGetDof(patch->intFacetCounts, point, &numIntFacets);CHKERRQ(ierr);
1885         ierr = PetscSectionGetOffset(patch->intFacetCounts, point, &intFacetOffset);CHKERRQ(ierr);
1886         ierr = ISGetIndices(patch->intFacetsToPatchCell, &facetCells);CHKERRQ(ierr);
1887         ierr = ISGetIndices(patch->intFacets, &intFacetsArray);CHKERRQ(ierr);
1888         for (i = 0; i < numIntFacets; i++) {
1889           const PetscInt cell0 = facetCells[2*(intFacetOffset + i) + 0];
1890           const PetscInt cell1 = facetCells[2*(intFacetOffset + i) + 1];
1891           const PetscInt *cell0idx = &dofsArray[(offset + cell0)*patch->totalDofsPerCell];
1892           const PetscInt *cell1idx = &dofsArray[(offset + cell1)*patch->totalDofsPerCell];
1893           ierr = MatSetValues(preallocator, patch->totalDofsPerCell, cell0idx, patch->totalDofsPerCell, cell1idx, vals, INSERT_VALUES);CHKERRQ(ierr);
1894           ierr = MatSetValues(preallocator, patch->totalDofsPerCell, cell1idx, patch->totalDofsPerCell, cell0idx, vals, INSERT_VALUES);CHKERRQ(ierr);
1895         }
1896       }
1897 
1898       ierr = PetscFree(vals);CHKERRQ(ierr);
1899       ierr = MatAssemblyBegin(preallocator, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1900       ierr = MatAssemblyEnd(preallocator, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1901       ierr = MatPreallocatorPreallocate(preallocator, PETSC_TRUE, *mat);CHKERRQ(ierr);
1902       ierr = MatDestroy(&preallocator);CHKERRQ(ierr);
1903     }
1904     ierr = PetscLogEventEnd(PC_Patch_Prealloc, pc, 0, 0, 0);CHKERRQ(ierr);
1905     if(withArtificial) {
1906       ierr = ISRestoreIndices(patch->dofsWithArtificial, &dofsArray);CHKERRQ(ierr);
1907     } else {
1908       ierr = ISRestoreIndices(patch->dofs, &dofsArray);CHKERRQ(ierr);
1909     }
1910   }
1911   ierr = MatSetUp(*mat);CHKERRQ(ierr);
1912   PetscFunctionReturn(0);
1913 }
1914 
1915 static PetscErrorCode PCPatchComputeFunction_DMPlex_Private(PC pc, PetscInt patchNum, Vec x, Vec F, IS cellIS, PetscInt n, const PetscInt *l2p, const PetscInt *l2pWithAll, void *ctx)
1916 {
1917   PC_PATCH       *patch = (PC_PATCH *) pc->data;
1918   DM              dm;
1919   PetscSection    s;
1920   const PetscInt *parray, *oarray;
1921   PetscInt        Nf = patch->nsubspaces, Np, poff, p, f;
1922   PetscErrorCode  ierr;
1923 
1924   PetscFunctionBegin;
1925   if (patch->precomputeElementTensors) SETERRQ(PetscObjectComm((PetscObject)pc), PETSC_ERR_ARG_WRONGSTATE, "Precomputing element tensors not implemented with DMPlex compute operator");
1926   ierr = PCGetDM(pc, &dm);CHKERRQ(ierr);
1927   ierr = DMGetDefaultSection(dm, &s);CHKERRQ(ierr);
1928   /* Set offset into patch */
1929   ierr = PetscSectionGetDof(patch->pointCounts, patchNum, &Np);CHKERRQ(ierr);
1930   ierr = PetscSectionGetOffset(patch->pointCounts, patchNum, &poff);CHKERRQ(ierr);
1931   ierr = ISGetIndices(patch->points, &parray);CHKERRQ(ierr);
1932   ierr = ISGetIndices(patch->offs,   &oarray);CHKERRQ(ierr);
1933   for (f = 0; f < Nf; ++f) {
1934     for (p = 0; p < Np; ++p) {
1935       const PetscInt point = parray[poff+p];
1936       PetscInt       dof;
1937 
1938       ierr = PetscSectionGetFieldDof(patch->patchSection, point, f, &dof);CHKERRQ(ierr);
1939       ierr = PetscSectionSetFieldOffset(patch->patchSection, point, f, oarray[(poff+p)*Nf+f]);CHKERRQ(ierr);
1940       if (patch->nsubspaces == 1) {ierr = PetscSectionSetOffset(patch->patchSection, point, oarray[(poff+p)*Nf+f]);CHKERRQ(ierr);}
1941       else                        {ierr = PetscSectionSetOffset(patch->patchSection, point, -1);CHKERRQ(ierr);}
1942     }
1943   }
1944   ierr = ISRestoreIndices(patch->points, &parray);CHKERRQ(ierr);
1945   ierr = ISRestoreIndices(patch->offs,   &oarray);CHKERRQ(ierr);
1946   if (patch->viewSection) {ierr = ObjectView((PetscObject) patch->patchSection, patch->viewerSection, patch->formatSection);CHKERRQ(ierr);}
1947   ierr = DMPlexComputeResidual_Patch_Internal(pc->dm, patch->patchSection, cellIS, 0.0, x, NULL, F, ctx);CHKERRQ(ierr);
1948   PetscFunctionReturn(0);
1949 }
1950 
1951 PetscErrorCode PCPatchComputeFunction_Internal(PC pc, Vec x, Vec F, PetscInt point)
1952 {
1953   PC_PATCH       *patch = (PC_PATCH *) pc->data;
1954   const PetscInt *dofsArray;
1955   const PetscInt *dofsArrayWithAll;
1956   const PetscInt *cellsArray;
1957   PetscInt        ncell, offset, pStart, pEnd;
1958   PetscErrorCode  ierr;
1959 
1960   PetscFunctionBegin;
1961   ierr = PetscLogEventBegin(PC_Patch_ComputeOp, pc, 0, 0, 0);CHKERRQ(ierr);
1962   if (!patch->usercomputeop) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call PCPatchSetComputeOperator() to set user callback\n");
1963   ierr = ISGetIndices(patch->dofs, &dofsArray);CHKERRQ(ierr);
1964   ierr = ISGetIndices(patch->dofsWithAll, &dofsArrayWithAll);CHKERRQ(ierr);
1965   ierr = ISGetIndices(patch->cells, &cellsArray);CHKERRQ(ierr);
1966   ierr = PetscSectionGetChart(patch->cellCounts, &pStart, &pEnd);CHKERRQ(ierr);
1967 
1968   point += pStart;
1969   if (point >= pEnd) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Operator point %D not in [%D, %D)\n", point, pStart, pEnd);CHKERRQ(ierr);
1970 
1971   ierr = PetscSectionGetDof(patch->cellCounts, point, &ncell);CHKERRQ(ierr);
1972   ierr = PetscSectionGetOffset(patch->cellCounts, point, &offset);CHKERRQ(ierr);
1973   if (ncell <= 0) {
1974     ierr = PetscLogEventEnd(PC_Patch_ComputeOp, pc, 0, 0, 0);CHKERRQ(ierr);
1975     PetscFunctionReturn(0);
1976   }
1977   PetscStackPush("PCPatch user callback");
1978   /* Cannot reuse the same IS because the geometry info is being cached in it */
1979   ierr = ISCreateGeneral(PETSC_COMM_SELF, ncell, cellsArray + offset, PETSC_USE_POINTER, &patch->cellIS);CHKERRQ(ierr);
1980   ierr = patch->usercomputef(pc, point, x, F, patch->cellIS, ncell*patch->totalDofsPerCell, dofsArray + offset*patch->totalDofsPerCell,
1981                                                                                             dofsArrayWithAll + offset*patch->totalDofsPerCell,
1982                                                                                             patch->usercomputefctx);CHKERRQ(ierr);
1983   PetscStackPop;
1984   ierr = ISDestroy(&patch->cellIS);CHKERRQ(ierr);
1985   ierr = ISRestoreIndices(patch->dofs, &dofsArray);CHKERRQ(ierr);
1986   ierr = ISRestoreIndices(patch->dofsWithAll, &dofsArrayWithAll);CHKERRQ(ierr);
1987   ierr = ISRestoreIndices(patch->cells, &cellsArray);CHKERRQ(ierr);
1988   if (patch->viewMatrix) {
1989     char name[PETSC_MAX_PATH_LEN];
1990 
1991     ierr = PetscSNPrintf(name, PETSC_MAX_PATH_LEN-1, "Patch vector for Point %D", point);CHKERRQ(ierr);
1992     ierr = PetscObjectSetName((PetscObject) F, name);CHKERRQ(ierr);
1993     ierr = ObjectView((PetscObject) F, patch->viewerMatrix, patch->formatMatrix);CHKERRQ(ierr);
1994   }
1995   ierr = PetscLogEventEnd(PC_Patch_ComputeOp, pc, 0, 0, 0);CHKERRQ(ierr);
1996   PetscFunctionReturn(0);
1997 }
1998 
1999 static PetscErrorCode PCPatchComputeOperator_DMPlex_Private(PC pc, PetscInt patchNum, Vec x, Mat J, IS cellIS, PetscInt n, const PetscInt *l2p, const PetscInt *l2pWithAll, void *ctx)
2000 {
2001   PC_PATCH       *patch = (PC_PATCH *) pc->data;
2002   DM              dm;
2003   PetscSection    s;
2004   const PetscInt *parray, *oarray;
2005   PetscInt        Nf = patch->nsubspaces, Np, poff, p, f;
2006   PetscErrorCode  ierr;
2007 
2008   PetscFunctionBegin;
2009   ierr = PCGetDM(pc, &dm);CHKERRQ(ierr);
2010   ierr = DMGetDefaultSection(dm, &s);CHKERRQ(ierr);
2011   /* Set offset into patch */
2012   ierr = PetscSectionGetDof(patch->pointCounts, patchNum, &Np);CHKERRQ(ierr);
2013   ierr = PetscSectionGetOffset(patch->pointCounts, patchNum, &poff);CHKERRQ(ierr);
2014   ierr = ISGetIndices(patch->points, &parray);CHKERRQ(ierr);
2015   ierr = ISGetIndices(patch->offs,   &oarray);CHKERRQ(ierr);
2016   for (f = 0; f < Nf; ++f) {
2017     for (p = 0; p < Np; ++p) {
2018       const PetscInt point = parray[poff+p];
2019       PetscInt       dof;
2020 
2021       ierr = PetscSectionGetFieldDof(patch->patchSection, point, f, &dof);CHKERRQ(ierr);
2022       ierr = PetscSectionSetFieldOffset(patch->patchSection, point, f, oarray[(poff+p)*Nf+f]);CHKERRQ(ierr);
2023       if (patch->nsubspaces == 1) {ierr = PetscSectionSetOffset(patch->patchSection, point, oarray[(poff+p)*Nf+f]);CHKERRQ(ierr);}
2024       else                        {ierr = PetscSectionSetOffset(patch->patchSection, point, -1);CHKERRQ(ierr);}
2025     }
2026   }
2027   ierr = ISRestoreIndices(patch->points, &parray);CHKERRQ(ierr);
2028   ierr = ISRestoreIndices(patch->offs,   &oarray);CHKERRQ(ierr);
2029   if (patch->viewSection) {ierr = ObjectView((PetscObject) patch->patchSection, patch->viewerSection, patch->formatSection);CHKERRQ(ierr);}
2030   /* TODO Shut off MatViewFromOptions() in MatAssemblyEnd() here */
2031   ierr = DMPlexComputeJacobian_Patch_Internal(pc->dm, patch->patchSection, patch->patchSection, cellIS, 0.0, 0.0, x, NULL, J, J, ctx);CHKERRQ(ierr);
2032   PetscFunctionReturn(0);
2033 }
2034 
2035 PetscErrorCode PCPatchComputeOperator_Internal(PC pc, Vec x, Mat mat, PetscInt point, PetscBool withArtificial)
2036 {
2037   PC_PATCH       *patch = (PC_PATCH *) pc->data;
2038   const PetscInt *dofsArray;
2039   const PetscInt *dofsArrayWithAll = NULL;
2040   const PetscInt *cellsArray;
2041   PetscInt        ncell, offset, pStart, pEnd, numIntFacets, intFacetOffset;
2042   PetscBool       isNonlinear;
2043   PetscErrorCode  ierr;
2044 
2045   PetscFunctionBegin;
2046   ierr = PetscLogEventBegin(PC_Patch_ComputeOp, pc, 0, 0, 0);CHKERRQ(ierr);
2047   isNonlinear = patch->isNonlinear;
2048   if (!patch->usercomputeop) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call PCPatchSetComputeOperator() to set user callback\n");
2049   if(withArtificial) {
2050     ierr = ISGetIndices(patch->dofsWithArtificial, &dofsArray);CHKERRQ(ierr);
2051   } else {
2052     ierr = ISGetIndices(patch->dofs, &dofsArray);CHKERRQ(ierr);
2053   }
2054   if (isNonlinear) {
2055     ierr = ISGetIndices(patch->dofsWithAll, &dofsArrayWithAll);CHKERRQ(ierr);
2056   }
2057   ierr = ISGetIndices(patch->cells, &cellsArray);CHKERRQ(ierr);
2058   ierr = PetscSectionGetChart(patch->cellCounts, &pStart, &pEnd);CHKERRQ(ierr);
2059 
2060   point += pStart;
2061   if (point >= pEnd) SETERRQ3(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Operator point %D not in [%D, %D)\n", point, pStart, pEnd);CHKERRQ(ierr);
2062 
2063   ierr = PetscSectionGetDof(patch->cellCounts, point, &ncell);CHKERRQ(ierr);
2064   ierr = PetscSectionGetOffset(patch->cellCounts, point, &offset);CHKERRQ(ierr);
2065   if (ncell <= 0) {
2066     ierr = PetscLogEventEnd(PC_Patch_ComputeOp, pc, 0, 0, 0);CHKERRQ(ierr);
2067     PetscFunctionReturn(0);
2068   }
2069   if (patch->precomputeElementTensors) {
2070     PetscInt           i;
2071     PetscInt           ndof = patch->totalDofsPerCell;
2072     const PetscScalar *elementTensors;
2073 
2074     ierr = VecGetArrayRead(patch->cellMats, &elementTensors);CHKERRQ(ierr);
2075     for (i = 0; i < ncell; i++) {
2076       const PetscInt     cell = cellsArray[i + offset];
2077       const PetscInt    *idx  = dofsArray + (offset + i)*ndof;
2078       const PetscScalar *v    = elementTensors + patch->precomputedTensorLocations[cell]*ndof*ndof;
2079       ierr = MatSetValues(mat, ndof, idx, ndof, idx, v, ADD_VALUES);CHKERRQ(ierr);
2080     }
2081     ierr = VecRestoreArrayRead(patch->cellMats, &elementTensors);CHKERRQ(ierr);
2082     ierr = MatAssemblyBegin(mat, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2083     ierr = MatAssemblyEnd(mat, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2084   } else {
2085     PetscStackPush("PCPatch user callback");
2086     /* Cannot reuse the same IS because the geometry info is being cached in it */
2087     ierr = ISCreateGeneral(PETSC_COMM_SELF, ncell, cellsArray + offset, PETSC_USE_POINTER, &patch->cellIS);CHKERRQ(ierr);
2088     ierr = patch->usercomputeop(pc, point, x, mat, patch->cellIS, ncell*patch->totalDofsPerCell, dofsArray + offset*patch->totalDofsPerCell, dofsArrayWithAll ? dofsArrayWithAll + offset*patch->totalDofsPerCell : NULL, patch->usercomputeopctx);CHKERRQ(ierr);
2089   }
2090   if (patch->usercomputeopintfacet) {
2091     ierr = PetscSectionGetDof(patch->intFacetCounts, point, &numIntFacets);CHKERRQ(ierr);
2092     ierr = PetscSectionGetOffset(patch->intFacetCounts, point, &intFacetOffset);CHKERRQ(ierr);
2093     if (numIntFacets > 0) {
2094       /* For each interior facet, grab the two cells (in local numbering, and concatenate dof numberings for those cells) */
2095       PetscInt       *facetDofs = NULL, *facetDofsWithAll = NULL;
2096       const PetscInt *intFacetsArray = NULL;
2097       PetscInt        idx = 0;
2098       PetscInt        i, c, d;
2099       PetscInt        fStart;
2100       DM              dm;
2101       IS              facetIS = NULL;
2102       const PetscInt *facetCells = NULL;
2103 
2104       ierr = ISGetIndices(patch->intFacetsToPatchCell, &facetCells);CHKERRQ(ierr);
2105       ierr = ISGetIndices(patch->intFacets, &intFacetsArray);CHKERRQ(ierr);
2106       ierr = PCGetDM(pc, &dm);CHKERRQ(ierr);
2107       ierr = DMPlexGetHeightStratum(dm, 1, &fStart, NULL);CHKERRQ(ierr);
2108       /* FIXME: Pull this malloc out. */
2109       ierr = PetscMalloc1(2 * patch->totalDofsPerCell * numIntFacets, &facetDofs);CHKERRQ(ierr);
2110       if (dofsArrayWithAll) {
2111         ierr = PetscMalloc1(2 * patch->totalDofsPerCell * numIntFacets, &facetDofsWithAll);CHKERRQ(ierr);
2112       }
2113       if (patch->precomputeElementTensors) {
2114         PetscInt           nFacetDof = 2*patch->totalDofsPerCell;
2115         const PetscScalar *elementTensors;
2116 
2117         ierr = VecGetArrayRead(patch->intFacetMats, &elementTensors);CHKERRQ(ierr);
2118 
2119         for (i = 0; i < numIntFacets; i++) {
2120           const PetscInt     facet = intFacetsArray[i + intFacetOffset];
2121           const PetscScalar *v     = elementTensors + patch->precomputedIntFacetTensorLocations[facet - fStart]*nFacetDof*nFacetDof;
2122           idx = 0;
2123           /*
2124            * 0--1
2125            * |\-|
2126            * |+\|
2127            * 2--3
2128            * [0, 2, 3, 0, 1, 3]
2129            */
2130           for (c = 0; c < 2; c++) {
2131             const PetscInt cell = facetCells[2*(intFacetOffset + i) + c];
2132             for (d = 0; d < patch->totalDofsPerCell; d++) {
2133               facetDofs[idx] = dofsArray[(offset + cell)*patch->totalDofsPerCell + d];
2134               idx++;
2135             }
2136           }
2137           ierr = MatSetValues(mat, nFacetDof, facetDofs, nFacetDof, facetDofs, v, ADD_VALUES);CHKERRQ(ierr);
2138         }
2139         ierr = VecRestoreArrayRead(patch->intFacetMats, &elementTensors);CHKERRQ(ierr);
2140       } else {
2141         /*
2142          * 0--1
2143          * |\-|
2144          * |+\|
2145          * 2--3
2146          * [0, 2, 3, 0, 1, 3]
2147          */
2148         for (i = 0; i < numIntFacets; i++) {
2149           for (c = 0; c < 2; c++) {
2150             const PetscInt cell = facetCells[2*(intFacetOffset + i) + c];
2151             for (d = 0; d < patch->totalDofsPerCell; d++) {
2152               facetDofs[idx] = dofsArray[(offset + cell)*patch->totalDofsPerCell + d];
2153               if (dofsArrayWithAll) {
2154                 facetDofsWithAll[idx] = dofsArrayWithAll[(offset + cell)*patch->totalDofsPerCell + d];
2155               }
2156               idx++;
2157             }
2158           }
2159         }
2160         ierr = ISCreateGeneral(PETSC_COMM_SELF, numIntFacets, intFacetsArray + intFacetOffset, PETSC_USE_POINTER, &facetIS);CHKERRQ(ierr);
2161         ierr = patch->usercomputeopintfacet(pc, point, x, mat, facetIS, 2*numIntFacets*patch->totalDofsPerCell, facetDofs, facetDofsWithAll, patch->usercomputeopintfacetctx);CHKERRQ(ierr);
2162         ierr = ISDestroy(&facetIS);CHKERRQ(ierr);
2163       }
2164       ierr = ISRestoreIndices(patch->intFacetsToPatchCell, &facetCells);CHKERRQ(ierr);
2165       ierr = ISRestoreIndices(patch->intFacets, &intFacetsArray);CHKERRQ(ierr);
2166       ierr = PetscFree(facetDofs);CHKERRQ(ierr);
2167       ierr = PetscFree(facetDofsWithAll);CHKERRQ(ierr);
2168     }
2169   }
2170 
2171   ierr = MatAssemblyBegin(mat, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2172   ierr = MatAssemblyEnd(mat, MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
2173 
2174   PetscStackPop;
2175   ierr = ISDestroy(&patch->cellIS);CHKERRQ(ierr);
2176   if(withArtificial) {
2177     ierr = ISRestoreIndices(patch->dofsWithArtificial, &dofsArray);CHKERRQ(ierr);
2178   } else {
2179     ierr = ISRestoreIndices(patch->dofs, &dofsArray);CHKERRQ(ierr);
2180   }
2181   if (isNonlinear) {
2182     ierr = ISRestoreIndices(patch->dofsWithAll, &dofsArrayWithAll);CHKERRQ(ierr);
2183   }
2184   ierr = ISRestoreIndices(patch->cells, &cellsArray);CHKERRQ(ierr);
2185   if (patch->viewMatrix) {
2186     char name[PETSC_MAX_PATH_LEN];
2187 
2188     ierr = PetscSNPrintf(name, PETSC_MAX_PATH_LEN-1, "Patch matrix for Point %D", point);CHKERRQ(ierr);
2189     ierr = PetscObjectSetName((PetscObject) mat, name);CHKERRQ(ierr);
2190     ierr = ObjectView((PetscObject) mat, patch->viewerMatrix, patch->formatMatrix);CHKERRQ(ierr);
2191   }
2192   ierr = PetscLogEventEnd(PC_Patch_ComputeOp, pc, 0, 0, 0);CHKERRQ(ierr);
2193   PetscFunctionReturn(0);
2194 }
2195 
2196 static PetscErrorCode MatSetValues_PCPatch_Private(Mat mat, PetscInt m, const PetscInt idxm[],
2197                                                    PetscInt n, const PetscInt idxn[], const PetscScalar *v, InsertMode addv)
2198 {
2199   Vec            data;
2200   PetscScalar   *array;
2201   PetscInt       bs, nz, i, j, cell;
2202   PetscErrorCode ierr;
2203 
2204   ierr = MatShellGetContext(mat, &data);CHKERRQ(ierr);
2205   ierr = VecGetBlockSize(data, &bs);CHKERRQ(ierr);
2206   ierr = VecGetSize(data, &nz);CHKERRQ(ierr);
2207   ierr = VecGetArray(data, &array);CHKERRQ(ierr);
2208   if (m != n) SETERRQ(PetscObjectComm((PetscObject)mat), PETSC_ERR_ARG_WRONG, "Only for square insertion");
2209   cell = (PetscInt)(idxm[0]/bs); // use the fact that this is called once per cell
2210   for (i = 0; i < m; i++) {
2211     //const PetscInt row = idxm[i];
2212     if (idxm[i] != idxn[i]) SETERRQ(PetscObjectComm((PetscObject)mat), PETSC_ERR_ARG_WRONG, "Row and column indices must match!");
2213     for (j = 0; j < n; j++) {
2214       const PetscScalar v_ = v[i*bs + j];
2215       /* Indexing is special to the data structure we have! */
2216       if (addv == INSERT_VALUES) {
2217         array[cell*bs*bs + i*bs + j] = v_;
2218       } else {
2219         array[cell*bs*bs + i*bs + j] += v_;
2220       }
2221     }
2222   }
2223   ierr = VecRestoreArray(data, &array);CHKERRQ(ierr);
2224   PetscFunctionReturn(0);
2225 }
2226 
2227 static PetscErrorCode PCPatchPrecomputePatchTensors_Private(PC pc)
2228 {
2229   PC_PATCH       *patch = (PC_PATCH *)pc->data;
2230   const PetscInt *cellsArray;
2231   PetscInt        ncell, offset;
2232   const PetscInt *dofMapArray;
2233   PetscInt        i, j;
2234   IS              dofMap;
2235   IS              cellIS;
2236   const PetscInt  ndof  = patch->totalDofsPerCell;
2237   PetscErrorCode  ierr;
2238   Mat             vecMat;
2239   PetscInt        cStart, cEnd;
2240   DM              dm, plex;
2241 
2242 
2243   ierr = PetscLogEventBegin(PC_Patch_ComputeOp, pc, 0, 0, 0);CHKERRQ(ierr);
2244 
2245   if (!patch->allCells) {
2246     PetscHSetI      cells;
2247     PetscHashIter   hi;
2248     PetscInt pStart, pEnd;
2249     PetscInt *allCells = NULL;
2250     ierr = PetscHSetICreate(&cells);CHKERRQ(ierr);
2251     ierr = ISGetIndices(patch->cells, &cellsArray);CHKERRQ(ierr);
2252     ierr = PetscSectionGetChart(patch->cellCounts, &pStart, &pEnd);CHKERRQ(ierr);
2253     for (i = pStart; i < pEnd; i++) {
2254       ierr = PetscSectionGetDof(patch->cellCounts, i, &ncell);CHKERRQ(ierr);
2255       ierr = PetscSectionGetOffset(patch->cellCounts, i, &offset);CHKERRQ(ierr);
2256       if (ncell <= 0) continue;
2257       for (j = 0; j < ncell; j++) {
2258         PetscHSetIAdd(cells, cellsArray[offset + j]);CHKERRQ(ierr);
2259       }
2260     }
2261     ierr = ISRestoreIndices(patch->cells, &cellsArray);CHKERRQ(ierr);
2262     ierr = PetscHSetIGetSize(cells, &ncell);CHKERRQ(ierr);
2263     ierr = PetscMalloc1(ncell, &allCells);CHKERRQ(ierr);
2264     ierr = PCGetDM(pc, &dm);CHKERRQ(ierr);
2265     ierr = DMConvert(dm, DMPLEX, &plex);CHKERRQ(ierr);
2266     ierr = DMPlexGetHeightStratum(dm, 0, &cStart, &cEnd);CHKERRQ(ierr);
2267     ierr = PetscMalloc1(cEnd-cStart, &patch->precomputedTensorLocations);CHKERRQ(ierr);
2268     i = 0;
2269     PetscHashIterBegin(cells, hi);
2270     while (!PetscHashIterAtEnd(cells, hi)) {
2271       PetscHashIterGetKey(cells, hi, allCells[i]);
2272       patch->precomputedTensorLocations[allCells[i]] = i;
2273       PetscHashIterNext(cells, hi);
2274       i++;
2275     }
2276     ierr = PetscHSetIDestroy(&cells);CHKERRQ(ierr);
2277     ierr = ISCreateGeneral(PETSC_COMM_SELF, ncell, allCells, PETSC_OWN_POINTER, &patch->allCells);CHKERRQ(ierr);
2278   }
2279   ierr = ISGetSize(patch->allCells, &ncell);CHKERRQ(ierr);
2280   if (!patch->cellMats) {
2281     ierr = VecCreateSeq(PETSC_COMM_SELF, ncell*ndof*ndof, &patch->cellMats);CHKERRQ(ierr);
2282     ierr = VecSetBlockSize(patch->cellMats, ndof);CHKERRQ(ierr);
2283   }
2284   ierr = VecSet(patch->cellMats, 0);CHKERRQ(ierr);
2285 
2286   ierr = MatCreateShell(PETSC_COMM_SELF, ncell*ndof, ncell*ndof, ncell*ndof, ncell*ndof,
2287                         (void*)patch->cellMats, &vecMat);
2288   ierr = MatShellSetOperation(vecMat, MATOP_SET_VALUES, (void(*)(void))&MatSetValues_PCPatch_Private);CHKERRQ(ierr);
2289   ierr = ISGetSize(patch->allCells, &ncell);CHKERRQ(ierr);
2290   ierr = ISCreateStride(PETSC_COMM_SELF, ndof*ncell, 0, 1, &dofMap);CHKERRQ(ierr);
2291   ierr = ISGetIndices(dofMap, &dofMapArray);CHKERRQ(ierr);
2292   ierr = ISGetIndices(patch->allCells, &cellsArray);CHKERRQ(ierr);
2293   ierr = ISCreateGeneral(PETSC_COMM_SELF, ncell, cellsArray, PETSC_USE_POINTER, &cellIS);CHKERRQ(ierr);
2294   PetscStackPush("PCPatch user callback");
2295   /* TODO: Fix for DMPlex compute op, this bypasses a lot of the machinery and just assembles every element tensor. */
2296   ierr = patch->usercomputeop(pc, -1, NULL, vecMat, cellIS, ndof*ncell, dofMapArray, NULL, patch->usercomputeopctx);CHKERRQ(ierr);
2297   PetscStackPop;
2298   ierr = ISDestroy(&cellIS);CHKERRQ(ierr);
2299   ierr = MatDestroy(&vecMat);CHKERRQ(ierr);
2300   ierr = ISRestoreIndices(patch->allCells, &cellsArray);CHKERRQ(ierr);
2301   ierr = ISRestoreIndices(dofMap, &dofMapArray);CHKERRQ(ierr);
2302   ierr = ISDestroy(&dofMap);CHKERRQ(ierr);
2303 
2304   if (patch->usercomputeopintfacet) {
2305     PetscInt nIntFacets;
2306     IS       intFacetsIS;
2307     const PetscInt *intFacetsArray = NULL;
2308     if (!patch->allIntFacets) {
2309       PetscHSetI      facets;
2310       PetscHashIter   hi;
2311       PetscInt pStart, pEnd, fStart, fEnd;
2312       PetscInt *allIntFacets = NULL;
2313       ierr = PetscHSetICreate(&facets);CHKERRQ(ierr);
2314       ierr = ISGetIndices(patch->intFacets, &intFacetsArray);CHKERRQ(ierr);
2315       ierr = PetscSectionGetChart(patch->intFacetCounts, &pStart, &pEnd);CHKERRQ(ierr);
2316       ierr = DMPlexGetHeightStratum(dm, 1, &fStart, &fEnd);CHKERRQ(ierr);
2317       for (i = pStart; i < pEnd; i++) {
2318         ierr = PetscSectionGetDof(patch->intFacetCounts, i, &nIntFacets);CHKERRQ(ierr);
2319         ierr = PetscSectionGetOffset(patch->intFacetCounts, i, &offset);CHKERRQ(ierr);
2320         if (nIntFacets <= 0) continue;
2321         for (j = 0; j < nIntFacets; j++) {
2322           PetscHSetIAdd(facets, intFacetsArray[offset + j]);CHKERRQ(ierr);
2323         }
2324       }
2325       ierr = ISRestoreIndices(patch->intFacets, &intFacetsArray);CHKERRQ(ierr);
2326       ierr = PetscHSetIGetSize(facets, &nIntFacets);CHKERRQ(ierr);
2327       ierr = PetscMalloc1(nIntFacets, &allIntFacets);CHKERRQ(ierr);
2328       ierr = PCGetDM(pc, &dm);CHKERRQ(ierr);
2329       ierr = DMConvert(dm, DMPLEX, &plex);CHKERRQ(ierr);
2330       ierr = PetscMalloc1(fEnd-fStart, &patch->precomputedIntFacetTensorLocations);CHKERRQ(ierr);
2331       i = 0;
2332       PetscHashIterBegin(facets, hi);
2333       while (!PetscHashIterAtEnd(facets, hi)) {
2334         PetscHashIterGetKey(facets, hi, allIntFacets[i]);
2335         patch->precomputedIntFacetTensorLocations[allIntFacets[i] - fStart] = i;
2336         PetscHashIterNext(facets, hi);
2337         i++;
2338       }
2339       ierr = PetscHSetIDestroy(&facets);CHKERRQ(ierr);
2340       ierr = ISCreateGeneral(PETSC_COMM_SELF, nIntFacets, allIntFacets, PETSC_OWN_POINTER, &patch->allIntFacets);CHKERRQ(ierr);
2341     }
2342     ierr = ISGetSize(patch->allIntFacets, &nIntFacets);CHKERRQ(ierr);
2343     if (!patch->intFacetMats) {
2344       ierr = VecCreateSeq(PETSC_COMM_SELF, nIntFacets*ndof*ndof*4, &patch->intFacetMats);CHKERRQ(ierr);
2345       ierr = VecSetBlockSize(patch->intFacetMats, ndof*2);CHKERRQ(ierr);
2346     }
2347     ierr = VecSet(patch->intFacetMats, 0);CHKERRQ(ierr);
2348 
2349     ierr = MatCreateShell(PETSC_COMM_SELF, nIntFacets*ndof*2, nIntFacets*ndof*2, nIntFacets*ndof*2, nIntFacets*ndof*2,
2350                           (void*)patch->intFacetMats, &vecMat);
2351     ierr = MatShellSetOperation(vecMat, MATOP_SET_VALUES, (void(*)(void))&MatSetValues_PCPatch_Private);CHKERRQ(ierr);
2352     ierr = ISCreateStride(PETSC_COMM_SELF, 2*ndof*nIntFacets, 0, 1, &dofMap);CHKERRQ(ierr);
2353     ierr = ISGetIndices(dofMap, &dofMapArray);CHKERRQ(ierr);
2354     ierr = ISGetIndices(patch->allIntFacets, &intFacetsArray);CHKERRQ(ierr);
2355     ierr = ISCreateGeneral(PETSC_COMM_SELF, nIntFacets, intFacetsArray, PETSC_USE_POINTER, &intFacetsIS);CHKERRQ(ierr);
2356     PetscStackPush("PCPatch user callback (interior facets)");
2357     /* TODO: Fix for DMPlex compute op, this bypasses a lot of the machinery and just assembles every element tensor. */
2358     ierr = patch->usercomputeopintfacet(pc, -1, NULL, vecMat, intFacetsIS, 2*ndof*nIntFacets, dofMapArray, NULL, patch->usercomputeopintfacetctx);CHKERRQ(ierr);
2359     PetscStackPop;
2360     ierr = ISDestroy(&intFacetsIS);CHKERRQ(ierr);
2361     ierr = MatDestroy(&vecMat);CHKERRQ(ierr);
2362     ierr = ISRestoreIndices(patch->allIntFacets, &intFacetsArray);CHKERRQ(ierr);
2363     ierr = ISRestoreIndices(dofMap, &dofMapArray);CHKERRQ(ierr);
2364     ierr = ISDestroy(&dofMap);CHKERRQ(ierr);
2365   }
2366   ierr = PetscLogEventEnd(PC_Patch_ComputeOp, pc, 0, 0, 0);CHKERRQ(ierr);
2367 
2368   PetscFunctionReturn(0);
2369 }
2370 
2371 PetscErrorCode PCPatch_ScatterLocal_Private(PC pc, PetscInt p, Vec x, Vec y, InsertMode mode, ScatterMode scat, PatchScatterType scattertype)
2372 {
2373   PC_PATCH          *patch     = (PC_PATCH *) pc->data;
2374   const PetscScalar *xArray    = NULL;
2375   PetscScalar       *yArray    = NULL;
2376   const PetscInt    *gtolArray = NULL;
2377   PetscInt           dof, offset, lidx;
2378   PetscErrorCode     ierr;
2379 
2380   PetscFunctionBeginHot;
2381   ierr = PetscLogEventBegin(PC_Patch_Scatter, pc, 0, 0, 0);CHKERRQ(ierr);
2382   ierr = VecGetArrayRead(x, &xArray);CHKERRQ(ierr);
2383   ierr = VecGetArray(y, &yArray);CHKERRQ(ierr);
2384   if (scattertype == SCATTER_WITHARTIFICIAL) {
2385     ierr = PetscSectionGetDof(patch->gtolCountsWithArtificial, p, &dof);CHKERRQ(ierr);
2386     ierr = PetscSectionGetOffset(patch->gtolCountsWithArtificial, p, &offset);CHKERRQ(ierr);
2387     ierr = ISGetIndices(patch->gtolWithArtificial, &gtolArray);CHKERRQ(ierr);
2388   } else if (scattertype == SCATTER_WITHALL) {
2389     ierr = PetscSectionGetDof(patch->gtolCountsWithAll, p, &dof);CHKERRQ(ierr);
2390     ierr = PetscSectionGetOffset(patch->gtolCountsWithAll, p, &offset);CHKERRQ(ierr);
2391     ierr = ISGetIndices(patch->gtolWithAll, &gtolArray);CHKERRQ(ierr);
2392   } else {
2393     ierr = PetscSectionGetDof(patch->gtolCounts, p, &dof);CHKERRQ(ierr);
2394     ierr = PetscSectionGetOffset(patch->gtolCounts, p, &offset);CHKERRQ(ierr);
2395     ierr = ISGetIndices(patch->gtol, &gtolArray);CHKERRQ(ierr);
2396   }
2397   if (mode == INSERT_VALUES && scat != SCATTER_FORWARD) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "Can't insert if not scattering forward\n");
2398   if (mode == ADD_VALUES    && scat != SCATTER_REVERSE) SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "Can't add if not scattering reverse\n");
2399   for (lidx = 0; lidx < dof; ++lidx) {
2400     const PetscInt gidx = gtolArray[offset+lidx];
2401 
2402     if (mode == INSERT_VALUES) yArray[lidx]  = xArray[gidx]; /* Forward */
2403     else                       yArray[gidx] += xArray[lidx]; /* Reverse */
2404   }
2405   if (scattertype == SCATTER_WITHARTIFICIAL) {
2406     ierr = ISRestoreIndices(patch->gtolWithArtificial, &gtolArray);CHKERRQ(ierr);
2407   } else if (scattertype == SCATTER_WITHALL) {
2408     ierr = ISRestoreIndices(patch->gtolWithAll, &gtolArray);CHKERRQ(ierr);
2409   } else {
2410     ierr = ISRestoreIndices(patch->gtol, &gtolArray);CHKERRQ(ierr);
2411   }
2412   ierr = VecRestoreArrayRead(x, &xArray);CHKERRQ(ierr);
2413   ierr = VecRestoreArray(y, &yArray);CHKERRQ(ierr);
2414   ierr = PetscLogEventEnd(PC_Patch_Scatter, pc, 0, 0, 0);CHKERRQ(ierr);
2415   PetscFunctionReturn(0);
2416 }
2417 
2418 static PetscErrorCode PCSetUp_PATCH_Linear(PC pc)
2419 {
2420   PC_PATCH      *patch = (PC_PATCH *) pc->data;
2421   const char    *prefix;
2422   PetscInt       i;
2423   PetscErrorCode ierr;
2424 
2425   PetscFunctionBegin;
2426   if (!pc->setupcalled) {
2427     ierr = PetscMalloc1(patch->npatch, &patch->solver);CHKERRQ(ierr);
2428     ierr = PCGetOptionsPrefix(pc, &prefix);CHKERRQ(ierr);
2429     for (i = 0; i < patch->npatch; ++i) {
2430       KSP ksp;
2431       PC  subpc;
2432 
2433       ierr = KSPCreate(PETSC_COMM_SELF, &ksp);CHKERRQ(ierr);
2434       ierr = KSPSetErrorIfNotConverged(ksp, pc->erroriffailure);CHKERRQ(ierr);
2435       ierr = KSPSetOptionsPrefix(ksp, prefix);CHKERRQ(ierr);
2436       ierr = KSPAppendOptionsPrefix(ksp, "sub_");CHKERRQ(ierr);
2437       ierr = PetscObjectIncrementTabLevel((PetscObject) ksp, (PetscObject) pc, 1);CHKERRQ(ierr);
2438       ierr = KSPGetPC(ksp, &subpc);CHKERRQ(ierr);
2439       ierr = PetscObjectIncrementTabLevel((PetscObject) subpc, (PetscObject) pc, 1);CHKERRQ(ierr);
2440       ierr = PetscLogObjectParent((PetscObject) pc, (PetscObject) ksp);CHKERRQ(ierr);
2441       patch->solver[i] = (PetscObject) ksp;
2442     }
2443   }
2444   if (patch->save_operators) {
2445     if (patch->precomputeElementTensors) {
2446       ierr = PCPatchPrecomputePatchTensors_Private(pc);CHKERRQ(ierr);
2447     }
2448     for (i = 0; i < patch->npatch; ++i) {
2449       ierr = MatZeroEntries(patch->mat[i]);CHKERRQ(ierr);
2450       ierr = PCPatchComputeOperator_Internal(pc, NULL, patch->mat[i], i, PETSC_FALSE);CHKERRQ(ierr);
2451       ierr = KSPSetOperators((KSP) patch->solver[i], patch->mat[i], patch->mat[i]);CHKERRQ(ierr);
2452     }
2453   }
2454   if(patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
2455     for (i = 0; i < patch->npatch; ++i) {
2456       /* Instead of padding patch->patchUpdate with zeros to get */
2457       /* patch->patchUpdateWithArtificial and then multiplying with the matrix, */
2458       /* just get rid of the columns that correspond to the dofs with */
2459       /* artificial bcs. That's of course fairly inefficient, hopefully we */
2460       /* can just assemble the rectangular matrix in the first place. */
2461       Mat matSquare;
2462       IS rowis;
2463       PetscInt dof;
2464 
2465       ierr = MatGetSize(patch->mat[i], &dof, NULL);CHKERRQ(ierr);
2466       if (dof == 0) {
2467         patch->matWithArtificial[i] = NULL;
2468         continue;
2469       }
2470 
2471       ierr = PCPatchCreateMatrix_Private(pc, i, &matSquare, PETSC_TRUE);CHKERRQ(ierr);
2472       ierr = MatZeroEntries(matSquare);CHKERRQ(ierr);
2473       ierr = PCPatchComputeOperator_Internal(pc, NULL, matSquare, i, PETSC_TRUE);CHKERRQ(ierr);
2474 
2475       ierr = MatGetSize(matSquare, &dof, NULL);CHKERRQ(ierr);
2476       ierr = ISCreateStride(PETSC_COMM_SELF, dof, 0, 1, &rowis); CHKERRQ(ierr);
2477       if(pc->setupcalled) {
2478         ierr = MatCreateSubMatrix(matSquare, rowis, patch->dofMappingWithoutToWithArtificial[i], MAT_REUSE_MATRIX, &patch->matWithArtificial[i]); CHKERRQ(ierr);
2479       } else {
2480         ierr = MatCreateSubMatrix(matSquare, rowis, patch->dofMappingWithoutToWithArtificial[i], MAT_INITIAL_MATRIX, &patch->matWithArtificial[i]); CHKERRQ(ierr);
2481       }
2482       ierr = ISDestroy(&rowis); CHKERRQ(ierr);
2483       ierr = MatDestroy(&matSquare);CHKERRQ(ierr);
2484     }
2485   }
2486   PetscFunctionReturn(0);
2487 }
2488 
2489 static PetscErrorCode PCSetUp_PATCH(PC pc)
2490 {
2491   PC_PATCH      *patch = (PC_PATCH *) pc->data;
2492   PetscInt       i;
2493   PetscBool       isNonlinear;
2494   PetscErrorCode ierr;
2495 
2496   PetscFunctionBegin;
2497   if (!pc->setupcalled) {
2498     PetscInt pStart, pEnd, p;
2499     PetscInt localSize;
2500 
2501     ierr = PetscLogEventBegin(PC_Patch_CreatePatches, pc, 0, 0, 0);CHKERRQ(ierr);
2502 
2503     isNonlinear = patch->isNonlinear;
2504     if (!patch->nsubspaces) {
2505       DM           dm;
2506       PetscSection s;
2507       PetscInt     cStart, cEnd, c, Nf, f, numGlobalBcs = 0, *globalBcs, *Nb, totNb = 0, **cellDofs;
2508 
2509       ierr = PCGetDM(pc, &dm);CHKERRQ(ierr);
2510       if (!dm) SETERRQ(PetscObjectComm((PetscObject) pc), PETSC_ERR_ARG_WRONG, "Must set DM for PCPATCH or call PCPatchSetDiscretisationInfo()");
2511       ierr = DMGetDefaultSection(dm, &s);CHKERRQ(ierr);
2512       ierr = PetscSectionGetNumFields(s, &Nf);CHKERRQ(ierr);
2513       ierr = PetscSectionGetChart(s, &pStart, &pEnd);CHKERRQ(ierr);
2514       for (p = pStart; p < pEnd; ++p) {
2515         PetscInt cdof;
2516         ierr = PetscSectionGetConstraintDof(s, p, &cdof);CHKERRQ(ierr);
2517         numGlobalBcs += cdof;
2518       }
2519       ierr = DMPlexGetHeightStratum(dm, 0, &cStart, &cEnd);CHKERRQ(ierr);
2520       ierr = PetscMalloc3(Nf, &Nb, Nf, &cellDofs, numGlobalBcs, &globalBcs);CHKERRQ(ierr);
2521       for (f = 0; f < Nf; ++f) {
2522         PetscFE        fe;
2523         PetscDualSpace sp;
2524         PetscInt       cdoff = 0;
2525 
2526         ierr = DMGetField(dm, f, NULL, (PetscObject *) &fe);CHKERRQ(ierr);
2527         /* ierr = PetscFEGetNumComponents(fe, &Nc[f]);CHKERRQ(ierr); */
2528         ierr = PetscFEGetDualSpace(fe, &sp);CHKERRQ(ierr);
2529         ierr = PetscDualSpaceGetDimension(sp, &Nb[f]);CHKERRQ(ierr);
2530         totNb += Nb[f];
2531 
2532         ierr = PetscMalloc1((cEnd-cStart)*Nb[f], &cellDofs[f]);CHKERRQ(ierr);
2533         for (c = cStart; c < cEnd; ++c) {
2534           PetscInt *closure = NULL;
2535           PetscInt  clSize  = 0, cl;
2536 
2537           ierr = DMPlexGetTransitiveClosure(dm, c, PETSC_TRUE, &clSize, &closure);CHKERRQ(ierr);
2538           for (cl = 0; cl < clSize*2; cl += 2) {
2539             const PetscInt p = closure[cl];
2540             PetscInt       fdof, d, foff;
2541 
2542             ierr = PetscSectionGetFieldDof(s, p, f, &fdof);CHKERRQ(ierr);
2543             ierr = PetscSectionGetFieldOffset(s, p, f, &foff);CHKERRQ(ierr);
2544             for (d = 0; d < fdof; ++d, ++cdoff) cellDofs[f][cdoff] = foff + d;
2545           }
2546           ierr = DMPlexRestoreTransitiveClosure(dm, c, PETSC_TRUE, &clSize, &closure);CHKERRQ(ierr);
2547         }
2548         if (cdoff != (cEnd-cStart)*Nb[f]) SETERRQ4(PetscObjectComm((PetscObject) pc), PETSC_ERR_ARG_SIZ, "Total number of cellDofs %D for field %D should be Nc (%D) * cellDof (%D)", cdoff, f, cEnd-cStart, Nb[f]);
2549       }
2550       numGlobalBcs = 0;
2551       for (p = pStart; p < pEnd; ++p) {
2552         const PetscInt *ind;
2553         PetscInt        off, cdof, d;
2554 
2555         ierr = PetscSectionGetOffset(s, p, &off);CHKERRQ(ierr);
2556         ierr = PetscSectionGetConstraintDof(s, p, &cdof);CHKERRQ(ierr);
2557         ierr = PetscSectionGetConstraintIndices(s, p, &ind);CHKERRQ(ierr);
2558         for (d = 0; d < cdof; ++d) globalBcs[numGlobalBcs++] = off + ind[d];
2559       }
2560 
2561       ierr = PCPatchSetDiscretisationInfoCombined(pc, dm, Nb, (const PetscInt **) cellDofs, numGlobalBcs, globalBcs, numGlobalBcs, globalBcs);CHKERRQ(ierr);
2562       for (f = 0; f < Nf; ++f) {
2563         ierr = PetscFree(cellDofs[f]);CHKERRQ(ierr);
2564       }
2565       ierr = PetscFree3(Nb, cellDofs, globalBcs);CHKERRQ(ierr);
2566       ierr = PCPatchSetComputeFunction(pc, PCPatchComputeFunction_DMPlex_Private, NULL);CHKERRQ(ierr);
2567       ierr = PCPatchSetComputeOperator(pc, PCPatchComputeOperator_DMPlex_Private, NULL);CHKERRQ(ierr);
2568     }
2569 
2570     localSize = patch->subspaceOffsets[patch->nsubspaces];
2571     ierr = VecCreateSeq(PETSC_COMM_SELF, localSize, &patch->localRHS);CHKERRQ(ierr);
2572     ierr = VecSetUp(patch->localRHS);CHKERRQ(ierr);
2573     ierr = VecDuplicate(patch->localRHS, &patch->localUpdate);CHKERRQ(ierr);
2574     ierr = PCPatchCreateCellPatches(pc);CHKERRQ(ierr);
2575     ierr = PCPatchCreateCellPatchDiscretisationInfo(pc);CHKERRQ(ierr);
2576 
2577     /* OK, now build the work vectors */
2578     ierr = PetscSectionGetChart(patch->gtolCounts, &pStart, &pEnd);CHKERRQ(ierr);
2579     ierr = PetscMalloc1(patch->npatch, &patch->patchRHS);CHKERRQ(ierr);
2580     ierr = PetscMalloc1(patch->npatch, &patch->patchUpdate);CHKERRQ(ierr);
2581 
2582     if (patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
2583       ierr = PetscMalloc1(patch->npatch, &patch->patchRHSWithArtificial);CHKERRQ(ierr);
2584       ierr = PetscMalloc1(patch->npatch, &patch->dofMappingWithoutToWithArtificial);CHKERRQ(ierr);
2585     }
2586     if (isNonlinear) {
2587       ierr = PetscMalloc1(patch->npatch, &patch->dofMappingWithoutToWithAll);CHKERRQ(ierr);
2588     }
2589     for (p = pStart; p < pEnd; ++p) {
2590       PetscInt dof;
2591 
2592       ierr = PetscSectionGetDof(patch->gtolCounts, p, &dof);CHKERRQ(ierr);
2593       ierr = VecCreateSeq(PETSC_COMM_SELF, dof, &patch->patchRHS[p-pStart]);CHKERRQ(ierr);
2594       ierr = VecSetUp(patch->patchRHS[p-pStart]);CHKERRQ(ierr);
2595       ierr = VecCreateSeq(PETSC_COMM_SELF, dof, &patch->patchUpdate[p-pStart]);CHKERRQ(ierr);
2596       ierr = VecSetUp(patch->patchUpdate[p-pStart]);CHKERRQ(ierr);
2597       if (patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
2598         const PetscInt    *gtolArray, *gtolArrayWithArtificial = NULL;
2599         PetscInt           numPatchDofs, offset;
2600         PetscInt           numPatchDofsWithArtificial, offsetWithArtificial;
2601         PetscInt           dofWithoutArtificialCounter = 0;
2602         PetscInt          *patchWithoutArtificialToWithArtificialArray;
2603 
2604         ierr = PetscSectionGetDof(patch->gtolCountsWithArtificial, p, &dof);CHKERRQ(ierr);
2605         ierr = VecCreateSeq(PETSC_COMM_SELF, dof, &patch->patchRHSWithArtificial[p-pStart]);CHKERRQ(ierr);
2606         ierr = VecSetUp(patch->patchRHSWithArtificial[p-pStart]);CHKERRQ(ierr);
2607 
2608         /* Now build the mapping that for a dof in a patch WITHOUT dofs that have artificial bcs gives the */
2609         /* the index in the patch with all dofs */
2610         ierr = ISGetIndices(patch->gtol, &gtolArray);CHKERRQ(ierr);
2611 
2612         ierr = PetscSectionGetDof(patch->gtolCounts, p, &numPatchDofs);CHKERRQ(ierr);
2613         if (numPatchDofs == 0) {
2614           patch->dofMappingWithoutToWithArtificial[p-pStart] = NULL;
2615           continue;
2616         }
2617 
2618         ierr = PetscSectionGetOffset(patch->gtolCounts, p, &offset);CHKERRQ(ierr);
2619         ierr = ISGetIndices(patch->gtolWithArtificial, &gtolArrayWithArtificial);CHKERRQ(ierr);
2620         ierr = PetscSectionGetDof(patch->gtolCountsWithArtificial, p, &numPatchDofsWithArtificial);CHKERRQ(ierr);
2621         ierr = PetscSectionGetOffset(patch->gtolCountsWithArtificial, p, &offsetWithArtificial);CHKERRQ(ierr);
2622 
2623         ierr = PetscMalloc1(numPatchDofs, &patchWithoutArtificialToWithArtificialArray);CHKERRQ(ierr);
2624         for (i=0; i<numPatchDofsWithArtificial; i++) {
2625           if (gtolArrayWithArtificial[i+offsetWithArtificial] == gtolArray[offset+dofWithoutArtificialCounter]) {
2626             patchWithoutArtificialToWithArtificialArray[dofWithoutArtificialCounter] = i;
2627             dofWithoutArtificialCounter++;
2628             if (dofWithoutArtificialCounter == numPatchDofs)
2629               break;
2630           }
2631         }
2632         ierr = ISCreateGeneral(PETSC_COMM_SELF, numPatchDofs, patchWithoutArtificialToWithArtificialArray, PETSC_OWN_POINTER, &patch->dofMappingWithoutToWithArtificial[p-pStart]);CHKERRQ(ierr);
2633         ierr = ISRestoreIndices(patch->gtol, &gtolArray);CHKERRQ(ierr);
2634         ierr = ISRestoreIndices(patch->gtolWithArtificial, &gtolArrayWithArtificial);CHKERRQ(ierr);
2635       }
2636       if (isNonlinear) {
2637         const PetscInt    *gtolArray, *gtolArrayWithAll = NULL;
2638         PetscInt           numPatchDofs, offset;
2639         PetscInt           numPatchDofsWithAll, offsetWithAll;
2640         PetscInt           dofWithoutAllCounter = 0;
2641         PetscInt          *patchWithoutAllToWithAllArray;
2642 
2643         /* Now build the mapping that for a dof in a patch WITHOUT dofs that have artificial bcs gives the */
2644         /* the index in the patch with all dofs */
2645         ierr = ISGetIndices(patch->gtol, &gtolArray);CHKERRQ(ierr);
2646 
2647         ierr = PetscSectionGetDof(patch->gtolCounts, p, &numPatchDofs);CHKERRQ(ierr);
2648         if (numPatchDofs == 0) {
2649           patch->dofMappingWithoutToWithAll[p-pStart] = NULL;
2650           continue;
2651         }
2652 
2653         ierr = PetscSectionGetOffset(patch->gtolCounts, p, &offset);CHKERRQ(ierr);
2654         ierr = ISGetIndices(patch->gtolWithAll, &gtolArrayWithAll);CHKERRQ(ierr);
2655         ierr = PetscSectionGetDof(patch->gtolCountsWithAll, p, &numPatchDofsWithAll);CHKERRQ(ierr);
2656         ierr = PetscSectionGetOffset(patch->gtolCountsWithAll, p, &offsetWithAll);CHKERRQ(ierr);
2657 
2658         ierr = PetscMalloc1(numPatchDofs, &patchWithoutAllToWithAllArray);CHKERRQ(ierr);
2659 
2660         for (i=0; i<numPatchDofsWithAll; i++) {
2661           if (gtolArrayWithAll[i+offsetWithAll] == gtolArray[offset+dofWithoutAllCounter]) {
2662             patchWithoutAllToWithAllArray[dofWithoutAllCounter] = i;
2663             dofWithoutAllCounter++;
2664             if (dofWithoutAllCounter == numPatchDofs)
2665               break;
2666           }
2667         }
2668         ierr = ISCreateGeneral(PETSC_COMM_SELF, numPatchDofs, patchWithoutAllToWithAllArray, PETSC_OWN_POINTER, &patch->dofMappingWithoutToWithAll[p-pStart]);CHKERRQ(ierr);
2669         ierr = ISRestoreIndices(patch->gtol, &gtolArray);CHKERRQ(ierr);
2670         ierr = ISRestoreIndices(patch->gtolWithAll, &gtolArrayWithAll);CHKERRQ(ierr);
2671       }
2672     }
2673     if (patch->save_operators) {
2674       ierr = PetscMalloc1(patch->npatch, &patch->mat);CHKERRQ(ierr);
2675       for (i = 0; i < patch->npatch; ++i) {
2676         ierr = PCPatchCreateMatrix_Private(pc, i, &patch->mat[i], PETSC_FALSE);CHKERRQ(ierr);
2677       }
2678     }
2679     ierr = PetscLogEventEnd(PC_Patch_CreatePatches, pc, 0, 0, 0);CHKERRQ(ierr);
2680 
2681     /* If desired, calculate weights for dof multiplicity */
2682     if (patch->partition_of_unity) {
2683       PetscScalar *input = NULL;
2684       PetscScalar *output = NULL;
2685       Vec global;
2686 
2687       ierr = VecDuplicate(patch->localRHS, &patch->dof_weights);CHKERRQ(ierr);
2688       if(patch->local_composition_type == PC_COMPOSITE_ADDITIVE) {
2689         for (i = 0; i < patch->npatch; ++i) {
2690           PetscInt dof;
2691 
2692           ierr = PetscSectionGetDof(patch->gtolCounts, i+pStart, &dof);CHKERRQ(ierr);
2693           if (dof <= 0) continue;
2694           ierr = VecSet(patch->patchRHS[i], 1.0);CHKERRQ(ierr);
2695           ierr = PCPatch_ScatterLocal_Private(pc, i+pStart, patch->patchRHS[i], patch->dof_weights, ADD_VALUES, SCATTER_REVERSE, SCATTER_INTERIOR);CHKERRQ(ierr);
2696         }
2697       } else {
2698         /* multiplicative is actually only locally multiplicative and globally additive. need the pou where the mesh decomposition overlaps */
2699         ierr = VecSet(patch->dof_weights, 1.0);CHKERRQ(ierr);
2700       }
2701 
2702       VecDuplicate(patch->dof_weights, &global);
2703       VecSet(global, 0.);
2704 
2705       ierr = VecGetArray(patch->dof_weights, &input);CHKERRQ(ierr);
2706       ierr = VecGetArray(global, &output);CHKERRQ(ierr);
2707       ierr = PetscSFReduceBegin(patch->defaultSF, MPIU_SCALAR, input, output, MPI_SUM);CHKERRQ(ierr);
2708       ierr = PetscSFReduceEnd(patch->defaultSF, MPIU_SCALAR, input, output, MPI_SUM);CHKERRQ(ierr);
2709       ierr = VecRestoreArray(patch->dof_weights, &input);CHKERRQ(ierr);
2710       ierr = VecRestoreArray(global, &output);CHKERRQ(ierr);
2711 
2712       ierr = VecReciprocal(global);CHKERRQ(ierr);
2713 
2714       ierr = VecGetArray(patch->dof_weights, &output);CHKERRQ(ierr);
2715       ierr = VecGetArray(global, &input);CHKERRQ(ierr);
2716       ierr = PetscSFBcastBegin(patch->defaultSF, MPIU_SCALAR, input, output);CHKERRQ(ierr);
2717       ierr = PetscSFBcastEnd(patch->defaultSF, MPIU_SCALAR, input, output);CHKERRQ(ierr);
2718       ierr = VecRestoreArray(patch->dof_weights, &output);CHKERRQ(ierr);
2719       ierr = VecRestoreArray(global, &input);CHKERRQ(ierr);
2720       ierr = VecDestroy(&global);CHKERRQ(ierr);
2721     }
2722     if(patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE && patch->save_operators) {
2723       ierr = PetscMalloc1(patch->npatch, &patch->matWithArtificial);CHKERRQ(ierr);
2724     }
2725   }
2726   ierr = (*patch->setupsolver)(pc);CHKERRQ(ierr);
2727   PetscFunctionReturn(0);
2728 }
2729 
2730 static PetscErrorCode PCApply_PATCH_Linear(PC pc, PetscInt i, Vec x, Vec y)
2731 {
2732   PC_PATCH      *patch = (PC_PATCH *) pc->data;
2733   KSP            ksp   = (KSP) patch->solver[i];
2734   PetscErrorCode ierr;
2735 
2736   PetscFunctionBegin;
2737   if (!patch->save_operators) {
2738     Mat mat;
2739 
2740     ierr = PCPatchCreateMatrix_Private(pc, i, &mat, PETSC_FALSE);CHKERRQ(ierr);
2741     /* Populate operator here. */
2742     ierr = PCPatchComputeOperator_Internal(pc, NULL, mat, i, PETSC_FALSE);CHKERRQ(ierr);
2743     ierr = KSPSetOperators(ksp, mat, mat);CHKERRQ(ierr);
2744     /* Drop reference so the KSPSetOperators below will blow it away. */
2745     ierr = MatDestroy(&mat);CHKERRQ(ierr);
2746   }
2747   ierr = PetscLogEventBegin(PC_Patch_Solve, pc, 0, 0, 0);CHKERRQ(ierr);
2748   if (!ksp->setfromoptionscalled) {
2749     ierr = KSPSetFromOptions(ksp);CHKERRQ(ierr);
2750   }
2751   ierr = KSPSolve(ksp, x, y);CHKERRQ(ierr);
2752   ierr = KSPCheckSolve(ksp, pc, y);CHKERRQ(ierr);
2753   ierr = PetscLogEventEnd(PC_Patch_Solve, pc, 0, 0, 0);CHKERRQ(ierr);
2754   if (!patch->save_operators) {
2755     PC pc;
2756     ierr = KSPSetOperators(ksp, NULL, NULL);CHKERRQ(ierr);
2757     ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
2758     /* Destroy PC context too, otherwise the factored matrix hangs around. */
2759     ierr = PCReset(pc);CHKERRQ(ierr);
2760   }
2761   PetscFunctionReturn(0);
2762 }
2763 
2764 static PetscErrorCode PCUpdateMultiplicative_PATCH_Linear(PC pc, PetscInt i, PetscInt pStart)
2765 {
2766   PC_PATCH      *patch = (PC_PATCH *) pc->data;
2767   Mat multMat;
2768   PetscErrorCode ierr;
2769 
2770   PetscFunctionBegin;
2771 
2772   if (patch->save_operators) {
2773     multMat = patch->matWithArtificial[i];
2774   } else {
2775     /*Very inefficient, hopefully we can just assemble the rectangular matrix in the first place.*/
2776     Mat matSquare;
2777     PetscInt dof;
2778     IS rowis;
2779     ierr = PCPatchCreateMatrix_Private(pc, i, &matSquare, PETSC_TRUE);CHKERRQ(ierr);
2780     ierr = MatZeroEntries(matSquare);CHKERRQ(ierr);
2781     ierr = PCPatchComputeOperator_Internal(pc, NULL, matSquare, i, PETSC_TRUE);CHKERRQ(ierr);
2782     ierr = MatGetSize(matSquare, &dof, NULL);CHKERRQ(ierr);
2783     ierr = ISCreateStride(PETSC_COMM_SELF, dof, 0, 1, &rowis); CHKERRQ(ierr);
2784     ierr = MatCreateSubMatrix(matSquare, rowis, patch->dofMappingWithoutToWithArtificial[i], MAT_INITIAL_MATRIX, &multMat); CHKERRQ(ierr);
2785     ierr = MatDestroy(&matSquare);CHKERRQ(ierr);
2786     ierr = ISDestroy(&rowis); CHKERRQ(ierr);
2787   }
2788   ierr = MatMult(multMat, patch->patchUpdate[i], patch->patchRHSWithArtificial[i]); CHKERRQ(ierr);
2789   ierr = VecScale(patch->patchRHSWithArtificial[i], -1.0); CHKERRQ(ierr);
2790   ierr = PCPatch_ScatterLocal_Private(pc, i + pStart, patch->patchRHSWithArtificial[i], patch->localRHS, ADD_VALUES, SCATTER_REVERSE, SCATTER_WITHARTIFICIAL); CHKERRQ(ierr);
2791   if (!patch->save_operators) {
2792     ierr = MatDestroy(&multMat); CHKERRQ(ierr);
2793   }
2794   PetscFunctionReturn(0);
2795 }
2796 
2797 static PetscErrorCode PCApply_PATCH(PC pc, Vec x, Vec y)
2798 {
2799   PC_PATCH          *patch    = (PC_PATCH *) pc->data;
2800   const PetscScalar *globalRHS  = NULL;
2801   PetscScalar       *localRHS   = NULL;
2802   PetscScalar       *globalUpdate  = NULL;
2803   const PetscInt    *bcNodes  = NULL;
2804   PetscInt           nsweep   = patch->symmetrise_sweep ? 2 : 1;
2805   PetscInt           start[2] = {0, 0};
2806   PetscInt           end[2]   = {-1, -1};
2807   const PetscInt     inc[2]   = {1, -1};
2808   const PetscScalar *localUpdate;
2809   const PetscInt    *iterationSet;
2810   PetscInt           pStart, numBcs, n, sweep, bc, j;
2811   PetscErrorCode     ierr;
2812 
2813   PetscFunctionBegin;
2814   ierr = PetscLogEventBegin(PC_Patch_Apply, pc, 0, 0, 0);CHKERRQ(ierr);
2815   ierr = PetscOptionsPushGetViewerOff(PETSC_TRUE);CHKERRQ(ierr);
2816   /* start, end, inc have 2 entries to manage a second backward sweep if we symmetrize */
2817   end[0]   = patch->npatch;
2818   start[1] = patch->npatch-1;
2819   if (patch->user_patches) {
2820     ierr = ISGetLocalSize(patch->iterationSet, &end[0]);CHKERRQ(ierr);
2821     start[1] = end[0] - 1;
2822     ierr = ISGetIndices(patch->iterationSet, &iterationSet);CHKERRQ(ierr);
2823   }
2824   /* Scatter from global space into overlapped local spaces */
2825   ierr = VecGetArrayRead(x, &globalRHS);CHKERRQ(ierr);
2826   ierr = VecGetArray(patch->localRHS, &localRHS);CHKERRQ(ierr);
2827   ierr = PetscSFBcastBegin(patch->defaultSF, MPIU_SCALAR, globalRHS, localRHS);CHKERRQ(ierr);
2828   ierr = PetscSFBcastEnd(patch->defaultSF, MPIU_SCALAR, globalRHS, localRHS);CHKERRQ(ierr);
2829   ierr = VecRestoreArrayRead(x, &globalRHS);CHKERRQ(ierr);
2830   ierr = VecRestoreArray(patch->localRHS, &localRHS);CHKERRQ(ierr);
2831 
2832   ierr = VecSet(patch->localUpdate, 0.0);CHKERRQ(ierr);
2833   ierr = PetscSectionGetChart(patch->gtolCounts, &pStart, NULL);CHKERRQ(ierr);
2834   for (sweep = 0; sweep < nsweep; sweep++) {
2835     for (j = start[sweep]; j*inc[sweep] < end[sweep]*inc[sweep]; j += inc[sweep]) {
2836       PetscInt i       = patch->user_patches ? iterationSet[j] : j;
2837       PetscInt start, len;
2838 
2839       ierr = PetscSectionGetDof(patch->gtolCounts, i+pStart, &len);CHKERRQ(ierr);
2840       ierr = PetscSectionGetOffset(patch->gtolCounts, i+pStart, &start);CHKERRQ(ierr);
2841       /* TODO: Squash out these guys in the setup as well. */
2842       if (len <= 0) continue;
2843       /* TODO: Do we need different scatters for X and Y? */
2844       ierr = PCPatch_ScatterLocal_Private(pc, i+pStart, patch->localRHS, patch->patchRHS[i], INSERT_VALUES, SCATTER_FORWARD, SCATTER_INTERIOR);CHKERRQ(ierr);
2845       ierr = (*patch->applysolver)(pc, i, patch->patchRHS[i], patch->patchUpdate[i]);CHKERRQ(ierr);
2846       ierr = PCPatch_ScatterLocal_Private(pc, i+pStart, patch->patchUpdate[i], patch->localUpdate, ADD_VALUES, SCATTER_REVERSE, SCATTER_INTERIOR);CHKERRQ(ierr);
2847       if(patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
2848         ierr = (*patch->updatemultiplicative)(pc, i, pStart);CHKERRQ(ierr);
2849       }
2850     }
2851   }
2852   if (patch->user_patches) {ierr = ISRestoreIndices(patch->iterationSet, &iterationSet);CHKERRQ(ierr);}
2853   /* XXX: should we do this on the global vector? */
2854   if (patch->partition_of_unity) {
2855     ierr = VecPointwiseMult(patch->localUpdate, patch->localUpdate, patch->dof_weights);CHKERRQ(ierr);
2856   }
2857   /* Now patch->localUpdate contains the solution of the patch solves, so we need to combine them all. */
2858   ierr = VecSet(y, 0.0);CHKERRQ(ierr);
2859   ierr = VecGetArray(y, &globalUpdate);CHKERRQ(ierr);
2860   ierr = VecGetArrayRead(patch->localUpdate, &localUpdate);CHKERRQ(ierr);
2861   ierr = PetscSFReduceBegin(patch->defaultSF, MPIU_SCALAR, localUpdate, globalUpdate, MPI_SUM);CHKERRQ(ierr);
2862   ierr = PetscSFReduceEnd(patch->defaultSF, MPIU_SCALAR, localUpdate, globalUpdate, MPI_SUM);CHKERRQ(ierr);
2863   ierr = VecRestoreArrayRead(patch->localUpdate, &localUpdate);CHKERRQ(ierr);
2864 
2865   /* Now we need to send the global BC values through */
2866   ierr = VecGetArrayRead(x, &globalRHS);CHKERRQ(ierr);
2867   ierr = ISGetSize(patch->globalBcNodes, &numBcs);CHKERRQ(ierr);
2868   ierr = ISGetIndices(patch->globalBcNodes, &bcNodes);CHKERRQ(ierr);
2869   ierr = VecGetLocalSize(x, &n);CHKERRQ(ierr);
2870   for (bc = 0; bc < numBcs; ++bc) {
2871     const PetscInt idx = bcNodes[bc];
2872     if (idx < n) globalUpdate[idx] = globalRHS[idx];
2873   }
2874 
2875   ierr = ISRestoreIndices(patch->globalBcNodes, &bcNodes);CHKERRQ(ierr);
2876   ierr = VecRestoreArrayRead(x, &globalRHS);CHKERRQ(ierr);
2877   ierr = VecRestoreArray(y, &globalUpdate);CHKERRQ(ierr);
2878 
2879   ierr = PetscOptionsPopGetViewerOff();CHKERRQ(ierr);
2880   ierr = PetscLogEventEnd(PC_Patch_Apply, pc, 0, 0, 0);CHKERRQ(ierr);
2881   PetscFunctionReturn(0);
2882 }
2883 
2884 static PetscErrorCode PCReset_PATCH_Linear(PC pc)
2885 {
2886   PC_PATCH      *patch = (PC_PATCH *) pc->data;
2887   PetscInt       i;
2888   PetscErrorCode ierr;
2889 
2890   PetscFunctionBegin;
2891   if (patch->solver) {
2892     for (i = 0; i < patch->npatch; ++i) {ierr = KSPReset((KSP) patch->solver[i]);CHKERRQ(ierr);}
2893   }
2894   PetscFunctionReturn(0);
2895 }
2896 
2897 static PetscErrorCode PCReset_PATCH(PC pc)
2898 {
2899   PC_PATCH      *patch = (PC_PATCH *) pc->data;
2900   PetscInt       i;
2901   PetscErrorCode ierr;
2902 
2903   PetscFunctionBegin;
2904 
2905   ierr = PetscSFDestroy(&patch->defaultSF);CHKERRQ(ierr);
2906   ierr = PetscSectionDestroy(&patch->cellCounts);CHKERRQ(ierr);
2907   ierr = PetscSectionDestroy(&patch->pointCounts);CHKERRQ(ierr);
2908   ierr = PetscSectionDestroy(&patch->cellNumbering);CHKERRQ(ierr);
2909   ierr = PetscSectionDestroy(&patch->gtolCounts);CHKERRQ(ierr);
2910   ierr = ISDestroy(&patch->gtol);CHKERRQ(ierr);
2911   ierr = ISDestroy(&patch->cells);CHKERRQ(ierr);
2912   ierr = ISDestroy(&patch->points);CHKERRQ(ierr);
2913   ierr = ISDestroy(&patch->dofs);CHKERRQ(ierr);
2914   ierr = ISDestroy(&patch->offs);CHKERRQ(ierr);
2915   ierr = PetscSectionDestroy(&patch->patchSection);CHKERRQ(ierr);
2916   ierr = ISDestroy(&patch->ghostBcNodes);CHKERRQ(ierr);
2917   ierr = ISDestroy(&patch->globalBcNodes);CHKERRQ(ierr);
2918   ierr = PetscSectionDestroy(&patch->gtolCountsWithArtificial);CHKERRQ(ierr);
2919   ierr = ISDestroy(&patch->gtolWithArtificial);CHKERRQ(ierr);
2920   ierr = ISDestroy(&patch->dofsWithArtificial);CHKERRQ(ierr);
2921   ierr = ISDestroy(&patch->offsWithArtificial);CHKERRQ(ierr);
2922   ierr = PetscSectionDestroy(&patch->gtolCountsWithAll);CHKERRQ(ierr);
2923   ierr = ISDestroy(&patch->gtolWithAll);CHKERRQ(ierr);
2924   ierr = ISDestroy(&patch->dofsWithAll);CHKERRQ(ierr);
2925   ierr = ISDestroy(&patch->offsWithAll);CHKERRQ(ierr);
2926   ierr = VecDestroy(&patch->cellMats);CHKERRQ(ierr);
2927   ierr = VecDestroy(&patch->intFacetMats);CHKERRQ(ierr);
2928   ierr = ISDestroy(&patch->allCells);CHKERRQ(ierr);
2929 
2930   if (patch->dofSection) for (i = 0; i < patch->nsubspaces; i++) {ierr = PetscSectionDestroy(&patch->dofSection[i]);CHKERRQ(ierr);}
2931   ierr = PetscFree(patch->dofSection);CHKERRQ(ierr);
2932   ierr = PetscFree(patch->bs);CHKERRQ(ierr);
2933   ierr = PetscFree(patch->nodesPerCell);CHKERRQ(ierr);
2934   if (patch->cellNodeMap) for (i = 0; i < patch->nsubspaces; i++) {ierr = PetscFree(patch->cellNodeMap[i]);CHKERRQ(ierr);}
2935   ierr = PetscFree(patch->cellNodeMap);CHKERRQ(ierr);
2936   ierr = PetscFree(patch->subspaceOffsets);CHKERRQ(ierr);
2937 
2938   ierr = (*patch->resetsolver)(pc);CHKERRQ(ierr);
2939 
2940   if (patch->subspaces_to_exclude) {
2941     PetscHSetIDestroy(&patch->subspaces_to_exclude);
2942   }
2943 
2944   ierr = VecDestroy(&patch->localRHS);CHKERRQ(ierr);
2945   ierr = VecDestroy(&patch->localUpdate);CHKERRQ(ierr);
2946   if (patch->patchRHS) {
2947     for (i = 0; i < patch->npatch; ++i) {ierr = VecDestroy(&patch->patchRHS[i]);CHKERRQ(ierr);}
2948     ierr = PetscFree(patch->patchRHS);CHKERRQ(ierr);
2949   }
2950   if (patch->patchUpdate) {
2951     for (i = 0; i < patch->npatch; ++i) {ierr = VecDestroy(&patch->patchUpdate[i]);CHKERRQ(ierr);}
2952     ierr = PetscFree(patch->patchUpdate);CHKERRQ(ierr);
2953   }
2954   ierr = VecDestroy(&patch->dof_weights);CHKERRQ(ierr);
2955   if (patch->patch_dof_weights) {
2956     for (i = 0; i < patch->npatch; ++i) {ierr = VecDestroy(&patch->patch_dof_weights[i]);CHKERRQ(ierr);}
2957     ierr = PetscFree(patch->patch_dof_weights);CHKERRQ(ierr);
2958   }
2959   if (patch->mat) {
2960     for (i = 0; i < patch->npatch; ++i) {ierr = MatDestroy(&patch->mat[i]);CHKERRQ(ierr);}
2961     ierr = PetscFree(patch->mat);CHKERRQ(ierr);
2962   }
2963   if (patch->matWithArtificial) {
2964     for (i = 0; i < patch->npatch; ++i) {ierr = MatDestroy(&patch->matWithArtificial[i]);CHKERRQ(ierr);}
2965     ierr = PetscFree(patch->matWithArtificial);CHKERRQ(ierr);
2966   }
2967   if (patch->patchRHSWithArtificial) {
2968     for (i = 0; i < patch->npatch; ++i) {ierr = VecDestroy(&patch->patchRHSWithArtificial[i]);CHKERRQ(ierr);}
2969     ierr = PetscFree(patch->patchRHSWithArtificial);CHKERRQ(ierr);
2970   }
2971   if(patch->dofMappingWithoutToWithArtificial) {
2972     for (i = 0; i < patch->npatch; ++i) {ierr = ISDestroy(&patch->dofMappingWithoutToWithArtificial[i]);CHKERRQ(ierr);}
2973     ierr = PetscFree(patch->dofMappingWithoutToWithArtificial);CHKERRQ(ierr);
2974 
2975   }
2976   if(patch->dofMappingWithoutToWithAll) {
2977     for (i = 0; i < patch->npatch; ++i) {ierr = ISDestroy(&patch->dofMappingWithoutToWithAll[i]);CHKERRQ(ierr);}
2978     ierr = PetscFree(patch->dofMappingWithoutToWithAll);CHKERRQ(ierr);
2979 
2980   }
2981   ierr = PetscFree(patch->sub_mat_type);CHKERRQ(ierr);
2982   if (patch->userIS) {
2983     for (i = 0; i < patch->npatch; ++i) {ierr = ISDestroy(&patch->userIS[i]);CHKERRQ(ierr);}
2984     ierr = PetscFree(patch->userIS);CHKERRQ(ierr);
2985   }
2986   ierr = PetscFree(patch->precomputedTensorLocations);CHKERRQ(ierr);
2987   ierr = PetscFree(patch->precomputedIntFacetTensorLocations);CHKERRQ(ierr);
2988 
2989   patch->bs          = 0;
2990   patch->cellNodeMap = NULL;
2991   patch->nsubspaces  = 0;
2992   ierr = ISDestroy(&patch->iterationSet);CHKERRQ(ierr);
2993 
2994   ierr = PetscViewerDestroy(&patch->viewerSection);CHKERRQ(ierr);
2995   PetscFunctionReturn(0);
2996 }
2997 
2998 static PetscErrorCode PCDestroy_PATCH_Linear(PC pc)
2999 {
3000   PC_PATCH      *patch = (PC_PATCH *) pc->data;
3001   PetscInt       i;
3002   PetscErrorCode ierr;
3003 
3004   PetscFunctionBegin;
3005   if (patch->solver) {
3006     for (i = 0; i < patch->npatch; ++i) {ierr = KSPDestroy((KSP *) &patch->solver[i]);CHKERRQ(ierr);}
3007     ierr = PetscFree(patch->solver);CHKERRQ(ierr);
3008   }
3009   PetscFunctionReturn(0);
3010 }
3011 
3012 static PetscErrorCode PCDestroy_PATCH(PC pc)
3013 {
3014   PC_PATCH      *patch = (PC_PATCH *) pc->data;
3015   PetscErrorCode ierr;
3016 
3017   PetscFunctionBegin;
3018   ierr = PCReset_PATCH(pc);CHKERRQ(ierr);
3019   ierr = (*patch->destroysolver)(pc);CHKERRQ(ierr);
3020   ierr = PetscFree(pc->data);CHKERRQ(ierr);
3021   PetscFunctionReturn(0);
3022 }
3023 
3024 static PetscErrorCode PCSetFromOptions_PATCH(PetscOptionItems *PetscOptionsObject, PC pc)
3025 {
3026   PC_PATCH            *patch = (PC_PATCH *) pc->data;
3027   PCPatchConstructType patchConstructionType = PC_PATCH_STAR;
3028   char                 sub_mat_type[PETSC_MAX_PATH_LEN];
3029   char                 option[PETSC_MAX_PATH_LEN];
3030   const char          *prefix;
3031   PetscBool            flg, dimflg, codimflg;
3032   MPI_Comm             comm;
3033   PetscInt            *ifields, nfields, k;
3034   PetscErrorCode       ierr;
3035   PCCompositeType loctype = PC_COMPOSITE_ADDITIVE;
3036 
3037   PetscFunctionBegin;
3038   ierr = PetscObjectGetComm((PetscObject) pc, &comm);CHKERRQ(ierr);
3039   ierr = PetscObjectGetOptionsPrefix((PetscObject) pc, &prefix);CHKERRQ(ierr);
3040   ierr = PetscOptionsHead(PetscOptionsObject, "Patch solver options");CHKERRQ(ierr);
3041 
3042   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_save_operators", patch->classname);CHKERRQ(ierr);
3043   ierr = PetscOptionsBool(option,  "Store all patch operators for lifetime of object?", "PCPatchSetSaveOperators", patch->save_operators, &patch->save_operators, &flg);CHKERRQ(ierr);
3044 
3045   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_precompute_element_tensors", patch->classname);
3046   ierr = PetscOptionsBool(option,  "Compute each element tensor only once?", "PCPatchSetPrecomputeElementTensors", patch->precomputeElementTensors, &patch->precomputeElementTensors, &flg);CHKERRQ(ierr);
3047   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_partition_of_unity", patch->classname);
3048   ierr = PetscOptionsBool(option, "Weight contributions by dof multiplicity?", "PCPatchSetPartitionOfUnity", patch->partition_of_unity, &patch->partition_of_unity, &flg);CHKERRQ(ierr);
3049 
3050   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_local_type", patch->classname);CHKERRQ(ierr);
3051   ierr = PetscOptionsEnum(option,"Type of local solver composition (additive or multiplicative)","PCPatchSetLocalComposition",PCCompositeTypes,(PetscEnum)loctype,(PetscEnum*)&loctype,&flg);CHKERRQ(ierr);
3052   if(flg) { ierr = PCPatchSetLocalComposition(pc, loctype);CHKERRQ(ierr);}
3053 
3054   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_construct_dim", patch->classname);CHKERRQ(ierr);
3055   ierr = PetscOptionsInt(option, "What dimension of mesh point to construct patches by? (0 = vertices)", "PCPATCH", patch->dim, &patch->dim, &dimflg);CHKERRQ(ierr);
3056   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_construct_codim", patch->classname);CHKERRQ(ierr);
3057   ierr = PetscOptionsInt(option, "What co-dimension of mesh point to construct patches by? (0 = cells)", "PCPATCH", patch->codim, &patch->codim, &codimflg);CHKERRQ(ierr);
3058   if (dimflg && codimflg) SETERRQ(comm, PETSC_ERR_ARG_WRONG, "Can only set one of dimension or co-dimension");
3059 
3060   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_construct_type", patch->classname);CHKERRQ(ierr);
3061   ierr = PetscOptionsEnum(option, "How should the patches be constructed?", "PCPatchSetConstructType", PCPatchConstructTypes, (PetscEnum) patchConstructionType, (PetscEnum *) &patchConstructionType, &flg);CHKERRQ(ierr);
3062   if (flg) {ierr = PCPatchSetConstructType(pc, patchConstructionType, NULL, NULL);CHKERRQ(ierr);}
3063 
3064   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_vanka_dim", patch->classname);CHKERRQ(ierr);
3065   ierr = PetscOptionsInt(option, "Topological dimension of entities for Vanka to ignore", "PCPATCH", patch->vankadim, &patch->vankadim, &flg);CHKERRQ(ierr);
3066 
3067   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_ignore_dim", patch->classname);CHKERRQ(ierr);
3068   ierr = PetscOptionsInt(option, "Topological dimension of entities for completion to ignore", "PCPATCH", patch->ignoredim, &patch->ignoredim, &flg);CHKERRQ(ierr);
3069 
3070   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_pardecomp_overlap", patch->classname);CHKERRQ(ierr);
3071   ierr = PetscOptionsInt(option, "What overlap should we use in construct type pardecomp?", "PCPATCH", patch->pardecomp_overlap, &patch->pardecomp_overlap, &flg);CHKERRQ(ierr);
3072 
3073   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_sub_mat_type", patch->classname);CHKERRQ(ierr);
3074   ierr = PetscOptionsFList(option, "Matrix type for patch solves", "PCPatchSetSubMatType", MatList, NULL, sub_mat_type, PETSC_MAX_PATH_LEN, &flg);CHKERRQ(ierr);
3075   if (flg) {ierr = PCPatchSetSubMatType(pc, sub_mat_type);CHKERRQ(ierr);}
3076 
3077   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_symmetrise_sweep", patch->classname);CHKERRQ(ierr);
3078   ierr = PetscOptionsBool(option, "Go start->end, end->start?", "PCPATCH", patch->symmetrise_sweep, &patch->symmetrise_sweep, &flg);CHKERRQ(ierr);
3079 
3080   /* If the user has set the number of subspaces, use that for the buffer size,
3081      otherwise use a large number */
3082   if (patch->nsubspaces <= 0) {
3083     nfields = 128;
3084   } else {
3085     nfields = patch->nsubspaces;
3086   }
3087   ierr = PetscMalloc1(nfields, &ifields);CHKERRQ(ierr);
3088   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_exclude_subspaces", patch->classname);CHKERRQ(ierr);
3089   ierr = PetscOptionsGetIntArray(((PetscObject)pc)->options,((PetscObject)pc)->prefix,option,ifields,&nfields,&flg);CHKERRQ(ierr);
3090   if (flg && (patchConstructionType == PC_PATCH_USER)) SETERRQ(comm, PETSC_ERR_ARG_INCOMP, "We cannot support excluding a subspace with user patches because we do not index patches with a mesh point");
3091   if (flg) {
3092     PetscHSetIClear(patch->subspaces_to_exclude);
3093     for (k = 0; k < nfields; k++) {
3094       PetscHSetIAdd(patch->subspaces_to_exclude, ifields[k]);
3095     }
3096   }
3097   ierr = PetscFree(ifields);CHKERRQ(ierr);
3098 
3099   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_patches_view", patch->classname);CHKERRQ(ierr);
3100   ierr = PetscOptionsBool(option, "Print out information during patch construction", "PCPATCH", patch->viewPatches, &patch->viewPatches, &flg);CHKERRQ(ierr);
3101   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_cells_view", patch->classname);CHKERRQ(ierr);
3102   ierr = PetscOptionsGetViewer(comm,((PetscObject) pc)->options, prefix, option, &patch->viewerCells, &patch->formatCells, &patch->viewCells);CHKERRQ(ierr);
3103   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_interior_facets_view", patch->classname);CHKERRQ(ierr);
3104   ierr = PetscOptionsGetViewer(comm,((PetscObject) pc)->options, prefix, option, &patch->viewerIntFacets, &patch->formatIntFacets, &patch->viewIntFacets);CHKERRQ(ierr);
3105   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_exterior_facets_view", patch->classname);CHKERRQ(ierr);
3106   ierr = PetscOptionsGetViewer(comm,((PetscObject) pc)->options, prefix, option, &patch->viewerExtFacets, &patch->formatExtFacets, &patch->viewExtFacets);CHKERRQ(ierr);
3107   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_points_view", patch->classname);CHKERRQ(ierr);
3108   ierr = PetscOptionsGetViewer(comm,((PetscObject) pc)->options, prefix, option, &patch->viewerPoints, &patch->formatPoints, &patch->viewPoints);CHKERRQ(ierr);
3109   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_section_view", patch->classname);CHKERRQ(ierr);
3110   ierr = PetscOptionsGetViewer(comm,((PetscObject) pc)->options, prefix, option, &patch->viewerSection, &patch->formatSection, &patch->viewSection);CHKERRQ(ierr);
3111   ierr = PetscSNPrintf(option, PETSC_MAX_PATH_LEN, "-%s_patch_mat_view", patch->classname);CHKERRQ(ierr);
3112   ierr = PetscOptionsGetViewer(comm,((PetscObject) pc)->options, prefix, option, &patch->viewerMatrix, &patch->formatMatrix, &patch->viewMatrix);CHKERRQ(ierr);
3113   ierr = PetscOptionsTail();CHKERRQ(ierr);
3114   patch->optionsSet = PETSC_TRUE;
3115   PetscFunctionReturn(0);
3116 }
3117 
3118 static PetscErrorCode PCSetUpOnBlocks_PATCH(PC pc)
3119 {
3120   PC_PATCH          *patch = (PC_PATCH*) pc->data;
3121   KSPConvergedReason reason;
3122   PetscInt           i;
3123   PetscErrorCode     ierr;
3124 
3125   PetscFunctionBegin;
3126   if (!patch->save_operators) {
3127     /* Can't do this here because the sub KSPs don't have an operator attached yet. */
3128     PetscFunctionReturn(0);
3129   }
3130   for (i = 0; i < patch->npatch; ++i) {
3131     if (!((KSP) patch->solver[i])->setfromoptionscalled) {
3132       ierr = KSPSetFromOptions((KSP) patch->solver[i]);CHKERRQ(ierr);
3133     }
3134     ierr = KSPSetUp((KSP) patch->solver[i]);CHKERRQ(ierr);
3135     ierr = KSPGetConvergedReason((KSP) patch->solver[i], &reason);CHKERRQ(ierr);
3136     if (reason == KSP_DIVERGED_PC_FAILED) pc->failedreason = PC_SUBPC_ERROR;
3137   }
3138   PetscFunctionReturn(0);
3139 }
3140 
3141 static PetscErrorCode PCView_PATCH(PC pc, PetscViewer viewer)
3142 {
3143   PC_PATCH      *patch = (PC_PATCH *) pc->data;
3144   PetscViewer    sviewer;
3145   PetscBool      isascii;
3146   PetscMPIInt    rank;
3147   PetscErrorCode ierr;
3148 
3149   PetscFunctionBegin;
3150   /* TODO Redo tabbing with set tbas in new style */
3151   ierr = PetscObjectTypeCompare((PetscObject) viewer, PETSCVIEWERASCII, &isascii);CHKERRQ(ierr);
3152   if (!isascii) PetscFunctionReturn(0);
3153   ierr = MPI_Comm_rank(PetscObjectComm((PetscObject) pc), &rank);CHKERRQ(ierr);
3154   ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
3155   ierr = PetscViewerASCIIPrintf(viewer, "Subspace Correction preconditioner with %d patches\n", patch->npatch);CHKERRQ(ierr);
3156   if(patch->local_composition_type == PC_COMPOSITE_MULTIPLICATIVE) {
3157     ierr = PetscViewerASCIIPrintf(viewer, "Schwarz type: multiplicative\n");CHKERRQ(ierr);
3158   } else {
3159     ierr = PetscViewerASCIIPrintf(viewer, "Schwarz type: additive\n");CHKERRQ(ierr);
3160   }
3161   if (patch->partition_of_unity) {ierr = PetscViewerASCIIPrintf(viewer, "Weighting by partition of unity\n");CHKERRQ(ierr);}
3162   else                           {ierr = PetscViewerASCIIPrintf(viewer, "Not weighting by partition of unity\n");CHKERRQ(ierr);}
3163   if (patch->symmetrise_sweep) {ierr = PetscViewerASCIIPrintf(viewer, "Symmetrising sweep (start->end, then end->start)\n");CHKERRQ(ierr);}
3164   else                         {ierr = PetscViewerASCIIPrintf(viewer, "Not symmetrising sweep\n");CHKERRQ(ierr);}
3165   if (!patch->precomputeElementTensors) {ierr = PetscViewerASCIIPrintf(viewer, "Not precomputing element tensors (overlapping cells rebuilt in every patch assembly)\n");CHKERRQ(ierr);}
3166   else                            {ierr = PetscViewerASCIIPrintf(viewer, "Precomputing element tensors (each cell assembled only once)\n");CHKERRQ(ierr);}
3167   if (!patch->save_operators) {ierr = PetscViewerASCIIPrintf(viewer, "Not saving patch operators (rebuilt every PCApply)\n");CHKERRQ(ierr);}
3168   else                        {ierr = PetscViewerASCIIPrintf(viewer, "Saving patch operators (rebuilt every PCSetUp)\n");CHKERRQ(ierr);}
3169   if (patch->patchconstructop == PCPatchConstruct_Star)       {ierr = PetscViewerASCIIPrintf(viewer, "Patch construction operator: star\n");CHKERRQ(ierr);}
3170   else if (patch->patchconstructop == PCPatchConstruct_Vanka) {ierr = PetscViewerASCIIPrintf(viewer, "Patch construction operator: Vanka\n");CHKERRQ(ierr);}
3171   else if (patch->patchconstructop == PCPatchConstruct_User)  {ierr = PetscViewerASCIIPrintf(viewer, "Patch construction operator: user-specified\n");CHKERRQ(ierr);}
3172   else                                                        {ierr = PetscViewerASCIIPrintf(viewer, "Patch construction operator: unknown\n");CHKERRQ(ierr);}
3173 
3174   if (patch->isNonlinear) {
3175     ierr = PetscViewerASCIIPrintf(viewer, "SNES on patches (all same):\n");CHKERRQ(ierr);
3176   } else {
3177     ierr = PetscViewerASCIIPrintf(viewer, "KSP on patches (all same):\n");CHKERRQ(ierr);
3178   }
3179   if (patch->solver) {
3180     ierr = PetscViewerGetSubViewer(viewer, PETSC_COMM_SELF, &sviewer);CHKERRQ(ierr);
3181     if (!rank) {
3182       ierr = PetscViewerASCIIPushTab(sviewer);CHKERRQ(ierr);
3183       ierr = PetscObjectView(patch->solver[0], sviewer);CHKERRQ(ierr);
3184       ierr = PetscViewerASCIIPopTab(sviewer);CHKERRQ(ierr);
3185     }
3186     ierr = PetscViewerRestoreSubViewer(viewer, PETSC_COMM_SELF, &sviewer);CHKERRQ(ierr);
3187   } else {
3188     ierr = PetscViewerASCIIPushTab(viewer);CHKERRQ(ierr);
3189     ierr = PetscViewerASCIIPrintf(viewer, "Solver not yet set.\n");CHKERRQ(ierr);
3190     ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
3191   }
3192   ierr = PetscViewerASCIIPopTab(viewer);CHKERRQ(ierr);
3193   PetscFunctionReturn(0);
3194 }
3195 
3196 /*MC
3197   PCPATCH - A PC object that encapsulates flexible definition of blocks for overlapping and non-overlapping
3198             small block additive preconditioners. Block definition is based on topology from
3199             a DM and equation numbering from a PetscSection.
3200 
3201   Options Database Keys:
3202 + -pc_patch_cells_view   - Views the process local cell numbers for each patch
3203 . -pc_patch_points_view  - Views the process local mesh point numbers for each patch
3204 . -pc_patch_g2l_view     - Views the map between global dofs and patch local dofs for each patch
3205 . -pc_patch_patches_view - Views the global dofs associated with each patch and its boundary
3206 - -pc_patch_sub_mat_view - Views the matrix associated with each patch
3207 
3208   Level: intermediate
3209 
3210 .seealso: PCType, PCCreate(), PCSetType()
3211 M*/
3212 PETSC_EXTERN PetscErrorCode PCCreate_Patch(PC pc)
3213 {
3214   PC_PATCH      *patch;
3215   PetscErrorCode ierr;
3216 
3217   PetscFunctionBegin;
3218   ierr = PetscNewLog(pc, &patch);CHKERRQ(ierr);
3219 
3220   if (patch->subspaces_to_exclude) {
3221     PetscHSetIDestroy(&patch->subspaces_to_exclude);
3222   }
3223   PetscHSetICreate(&patch->subspaces_to_exclude);
3224 
3225   patch->classname = "pc";
3226   patch->isNonlinear = PETSC_FALSE;
3227 
3228   /* Set some defaults */
3229   patch->combined           = PETSC_FALSE;
3230   patch->save_operators     = PETSC_TRUE;
3231   patch->local_composition_type = PC_COMPOSITE_ADDITIVE;
3232   patch->precomputeElementTensors = PETSC_FALSE;
3233   patch->partition_of_unity = PETSC_FALSE;
3234   patch->codim              = -1;
3235   patch->dim                = -1;
3236   patch->vankadim           = -1;
3237   patch->ignoredim          = -1;
3238   patch->pardecomp_overlap  = 0;
3239   patch->patchconstructop   = PCPatchConstruct_Star;
3240   patch->symmetrise_sweep   = PETSC_FALSE;
3241   patch->npatch             = 0;
3242   patch->userIS             = NULL;
3243   patch->optionsSet         = PETSC_FALSE;
3244   patch->iterationSet       = NULL;
3245   patch->user_patches       = PETSC_FALSE;
3246   ierr = PetscStrallocpy(MATDENSE, (char **) &patch->sub_mat_type);CHKERRQ(ierr);
3247   patch->viewPatches        = PETSC_FALSE;
3248   patch->viewCells          = PETSC_FALSE;
3249   patch->viewPoints         = PETSC_FALSE;
3250   patch->viewSection        = PETSC_FALSE;
3251   patch->viewMatrix         = PETSC_FALSE;
3252   patch->setupsolver        = PCSetUp_PATCH_Linear;
3253   patch->applysolver        = PCApply_PATCH_Linear;
3254   patch->resetsolver        = PCReset_PATCH_Linear;
3255   patch->destroysolver      = PCDestroy_PATCH_Linear;
3256   patch->updatemultiplicative = PCUpdateMultiplicative_PATCH_Linear;
3257   patch->dofMappingWithoutToWithArtificial = NULL;
3258   patch->dofMappingWithoutToWithAll = NULL;
3259 
3260   pc->data                 = (void *) patch;
3261   pc->ops->apply           = PCApply_PATCH;
3262   pc->ops->applytranspose  = 0; /* PCApplyTranspose_PATCH; */
3263   pc->ops->setup           = PCSetUp_PATCH;
3264   pc->ops->reset           = PCReset_PATCH;
3265   pc->ops->destroy         = PCDestroy_PATCH;
3266   pc->ops->setfromoptions  = PCSetFromOptions_PATCH;
3267   pc->ops->setuponblocks   = PCSetUpOnBlocks_PATCH;
3268   pc->ops->view            = PCView_PATCH;
3269   pc->ops->applyrichardson = 0;
3270 
3271   PetscFunctionReturn(0);
3272 }
3273