xref: /petsc/src/mat/impls/sell/mpi/mpisell.c (revision 421480d92be24cdb9933c60510b8e175c0a8d034)
1 #include <../src/mat/impls/aij/mpi/mpiaij.h>   /*I "petscmat.h" I*/
2 #include <../src/mat/impls/sell/mpi/mpisell.h> /*I "petscmat.h" I*/
3 #include <petsc/private/vecimpl.h>
4 #include <petsc/private/isimpl.h>
5 #include <petscblaslapack.h>
6 #include <petscsf.h>
7 
8 /*MC
9    MATSELL - MATSELL = "sell" - A matrix type to be used for sparse matrices.
10 
11    This matrix type is identical to `MATSEQSELL` when constructed with a single process communicator,
12    and `MATMPISELL` otherwise.  As a result, for single process communicators,
13   `MatSeqSELLSetPreallocation()` is supported, and similarly `MatMPISELLSetPreallocation()` is supported
14   for communicators controlling multiple processes.  It is recommended that you call both of
15   the above preallocation routines for simplicity.
16 
17    Options Database Keys:
18 . -mat_type sell - sets the matrix type to `MATSELL` during a call to `MatSetFromOptions()`
19 
20   Level: beginner
21 
22 .seealso: `Mat`, `MATAIJ`, `MATBAIJ`, `MATSBAIJ`, `MatCreateSELL()`, `MatCreateSeqSELL()`, `MATSEQSELL`, `MATMPISELL`
23 M*/
24 
25 static PetscErrorCode MatDiagonalSet_MPISELL(Mat Y, Vec D, InsertMode is)
26 {
27   Mat_MPISELL *sell = (Mat_MPISELL *)Y->data;
28 
29   PetscFunctionBegin;
30   if (Y->assembled && Y->rmap->rstart == Y->cmap->rstart && Y->rmap->rend == Y->cmap->rend) {
31     PetscCall(MatDiagonalSet(sell->A, D, is));
32   } else {
33     PetscCall(MatDiagonalSet_Default(Y, D, is));
34   }
35   PetscFunctionReturn(PETSC_SUCCESS);
36 }
37 
38 /*
39   Local utility routine that creates a mapping from the global column
40 number to the local number in the off-diagonal part of the local
41 storage of the matrix.  When PETSC_USE_CTABLE is used this is scalable at
42 a slightly higher hash table cost; without it it is not scalable (each processor
43 has an order N integer array but is fast to access.
44 */
45 PetscErrorCode MatCreateColmap_MPISELL_Private(Mat mat)
46 {
47   Mat_MPISELL *sell = (Mat_MPISELL *)mat->data;
48   PetscInt     n    = sell->B->cmap->n, i;
49 
50   PetscFunctionBegin;
51   PetscCheck(sell->garray, PETSC_COMM_SELF, PETSC_ERR_PLIB, "MPISELL Matrix was assembled but is missing garray");
52 #if defined(PETSC_USE_CTABLE)
53   PetscCall(PetscHMapICreateWithSize(n, &sell->colmap));
54   for (i = 0; i < n; i++) PetscCall(PetscHMapISet(sell->colmap, sell->garray[i] + 1, i + 1));
55 #else
56   PetscCall(PetscCalloc1(mat->cmap->N + 1, &sell->colmap));
57   for (i = 0; i < n; i++) sell->colmap[sell->garray[i]] = i + 1;
58 #endif
59   PetscFunctionReturn(PETSC_SUCCESS);
60 }
61 
62 #define MatSetValues_SeqSELL_A_Private(row, col, value, addv, orow, ocol) \
63   { \
64     if (col <= lastcol1) low1 = 0; \
65     else high1 = nrow1; \
66     lastcol1 = col; \
67     while (high1 - low1 > 5) { \
68       t = (low1 + high1) / 2; \
69       if (cp1[sliceheight * t] > col) high1 = t; \
70       else low1 = t; \
71     } \
72     for (_i = low1; _i < high1; _i++) { \
73       if (cp1[sliceheight * _i] > col) break; \
74       if (cp1[sliceheight * _i] == col) { \
75         if (addv == ADD_VALUES) vp1[sliceheight * _i] += value; \
76         else vp1[sliceheight * _i] = value; \
77         inserted = PETSC_TRUE; \
78         goto a_noinsert; \
79       } \
80     } \
81     if (value == 0.0 && ignorezeroentries) { \
82       low1  = 0; \
83       high1 = nrow1; \
84       goto a_noinsert; \
85     } \
86     if (nonew == 1) { \
87       low1  = 0; \
88       high1 = nrow1; \
89       goto a_noinsert; \
90     } \
91     PetscCheck(nonew != -1, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Inserting a new nonzero at global row/column (%" PetscInt_FMT ", %" PetscInt_FMT ") into matrix", orow, ocol); \
92     MatSeqXSELLReallocateSELL(A, am, 1, nrow1, a->sliidx, a->sliceheight, row / sliceheight, row, col, a->colidx, a->val, cp1, vp1, nonew, MatScalar); \
93     /* shift up all the later entries in this row */ \
94     for (ii = nrow1 - 1; ii >= _i; ii--) { \
95       cp1[sliceheight * (ii + 1)] = cp1[sliceheight * ii]; \
96       vp1[sliceheight * (ii + 1)] = vp1[sliceheight * ii]; \
97     } \
98     cp1[sliceheight * _i] = col; \
99     vp1[sliceheight * _i] = value; \
100     a->nz++; \
101     nrow1++; \
102   a_noinsert:; \
103     a->rlen[row] = nrow1; \
104   }
105 
106 #define MatSetValues_SeqSELL_B_Private(row, col, value, addv, orow, ocol) \
107   { \
108     if (col <= lastcol2) low2 = 0; \
109     else high2 = nrow2; \
110     lastcol2 = col; \
111     while (high2 - low2 > 5) { \
112       t = (low2 + high2) / 2; \
113       if (cp2[sliceheight * t] > col) high2 = t; \
114       else low2 = t; \
115     } \
116     for (_i = low2; _i < high2; _i++) { \
117       if (cp2[sliceheight * _i] > col) break; \
118       if (cp2[sliceheight * _i] == col) { \
119         if (addv == ADD_VALUES) vp2[sliceheight * _i] += value; \
120         else vp2[sliceheight * _i] = value; \
121         inserted = PETSC_TRUE; \
122         goto b_noinsert; \
123       } \
124     } \
125     if (value == 0.0 && ignorezeroentries) { \
126       low2  = 0; \
127       high2 = nrow2; \
128       goto b_noinsert; \
129     } \
130     if (nonew == 1) { \
131       low2  = 0; \
132       high2 = nrow2; \
133       goto b_noinsert; \
134     } \
135     PetscCheck(nonew != -1, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Inserting a new nonzero at global row/column (%" PetscInt_FMT ", %" PetscInt_FMT ") into matrix", orow, ocol); \
136     MatSeqXSELLReallocateSELL(B, bm, 1, nrow2, b->sliidx, b->sliceheight, row / sliceheight, row, col, b->colidx, b->val, cp2, vp2, nonew, MatScalar); \
137     /* shift up all the later entries in this row */ \
138     for (ii = nrow2 - 1; ii >= _i; ii--) { \
139       cp2[sliceheight * (ii + 1)] = cp2[sliceheight * ii]; \
140       vp2[sliceheight * (ii + 1)] = vp2[sliceheight * ii]; \
141     } \
142     cp2[sliceheight * _i] = col; \
143     vp2[sliceheight * _i] = value; \
144     b->nz++; \
145     nrow2++; \
146   b_noinsert:; \
147     b->rlen[row] = nrow2; \
148   }
149 
150 static PetscErrorCode MatSetValues_MPISELL(Mat mat, PetscInt m, const PetscInt im[], PetscInt n, const PetscInt in[], const PetscScalar v[], InsertMode addv)
151 {
152   Mat_MPISELL *sell = (Mat_MPISELL *)mat->data;
153   PetscScalar  value;
154   PetscInt     i, j, rstart = mat->rmap->rstart, rend = mat->rmap->rend, shift1, shift2;
155   PetscInt     cstart = mat->cmap->rstart, cend = mat->cmap->rend, row, col;
156   PetscBool    roworiented = sell->roworiented;
157 
158   /* Some Variables required in the macro */
159   Mat          A                 = sell->A;
160   Mat_SeqSELL *a                 = (Mat_SeqSELL *)A->data;
161   PetscBool    ignorezeroentries = a->ignorezeroentries, found;
162   Mat          B                 = sell->B;
163   Mat_SeqSELL *b                 = (Mat_SeqSELL *)B->data;
164   PetscInt    *cp1, *cp2, ii, _i, nrow1, nrow2, low1, high1, low2, high2, t, lastcol1, lastcol2, sliceheight = a->sliceheight;
165   MatScalar   *vp1, *vp2;
166 
167   PetscFunctionBegin;
168   for (i = 0; i < m; i++) {
169     if (im[i] < 0) continue;
170     PetscCheck(im[i] < mat->rmap->N, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Row too large: row %" PetscInt_FMT " max %" PetscInt_FMT, im[i], mat->rmap->N - 1);
171     if (im[i] >= rstart && im[i] < rend) {
172       row      = im[i] - rstart;
173       lastcol1 = -1;
174       shift1   = a->sliidx[row / sliceheight] + (row % sliceheight); /* starting index of the row */
175       cp1      = PetscSafePointerPlusOffset(a->colidx, shift1);
176       vp1      = PetscSafePointerPlusOffset(a->val, shift1);
177       nrow1    = a->rlen[row];
178       low1     = 0;
179       high1    = nrow1;
180       lastcol2 = -1;
181       shift2   = b->sliidx[row / sliceheight] + (row % sliceheight); /* starting index of the row */
182       cp2      = PetscSafePointerPlusOffset(b->colidx, shift2);
183       vp2      = PetscSafePointerPlusOffset(b->val, shift2);
184       nrow2    = b->rlen[row];
185       low2     = 0;
186       high2    = nrow2;
187 
188       for (j = 0; j < n; j++) {
189         if (roworiented) value = v[i * n + j];
190         else value = v[i + j * m];
191         if (ignorezeroentries && value == 0.0 && (addv == ADD_VALUES)) continue;
192         if (in[j] >= cstart && in[j] < cend) {
193           col = in[j] - cstart;
194           MatSetValue_SeqSELL_Private(A, row, col, value, addv, im[i], in[j], cp1, vp1, lastcol1, low1, high1); /* set one value */
195 #if defined(PETSC_HAVE_CUDA)
196           if (A->offloadmask != PETSC_OFFLOAD_UNALLOCATED && found) A->offloadmask = PETSC_OFFLOAD_CPU;
197 #endif
198         } else if (in[j] < 0) {
199           continue;
200         } else {
201           PetscCheck(in[j] < mat->cmap->N, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Column too large: col %" PetscInt_FMT " max %" PetscInt_FMT, in[j], mat->cmap->N - 1);
202           if (mat->was_assembled) {
203             if (!sell->colmap) PetscCall(MatCreateColmap_MPISELL_Private(mat));
204 #if defined(PETSC_USE_CTABLE)
205             PetscCall(PetscHMapIGetWithDefault(sell->colmap, in[j] + 1, 0, &col));
206             col--;
207 #else
208             col = sell->colmap[in[j]] - 1;
209 #endif
210             if (col < 0 && !((Mat_SeqSELL *)sell->B->data)->nonew) {
211               PetscCall(MatDisAssemble_MPISELL(mat));
212               col = in[j];
213               /* Reinitialize the variables required by MatSetValues_SeqSELL_B_Private() */
214               B      = sell->B;
215               b      = (Mat_SeqSELL *)B->data;
216               shift2 = b->sliidx[row / sliceheight] + (row % sliceheight); /* starting index of the row */
217               cp2    = b->colidx + shift2;
218               vp2    = b->val + shift2;
219               nrow2  = b->rlen[row];
220               low2   = 0;
221               high2  = nrow2;
222               found  = PETSC_FALSE;
223             } else {
224               PetscCheck(col >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Inserting a new nonzero at global row/column (%" PetscInt_FMT ", %" PetscInt_FMT ") into matrix", im[i], in[j]);
225             }
226           } else col = in[j];
227           MatSetValue_SeqSELL_Private(B, row, col, value, addv, im[i], in[j], cp2, vp2, lastcol2, low2, high2); /* set one value */
228 #if defined(PETSC_HAVE_CUDA)
229           if (B->offloadmask != PETSC_OFFLOAD_UNALLOCATED && found) B->offloadmask = PETSC_OFFLOAD_CPU;
230 #endif
231         }
232       }
233     } else {
234       PetscCheck(!mat->nooffprocentries, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Setting off process row %" PetscInt_FMT " even though MatSetOption(,MAT_NO_OFF_PROC_ENTRIES,PETSC_TRUE) was set", im[i]);
235       if (!sell->donotstash) {
236         mat->assembled = PETSC_FALSE;
237         if (roworiented) {
238           PetscCall(MatStashValuesRow_Private(&mat->stash, im[i], n, in, v + i * n, (PetscBool)(ignorezeroentries && (addv == ADD_VALUES))));
239         } else {
240           PetscCall(MatStashValuesCol_Private(&mat->stash, im[i], n, in, v + i, m, (PetscBool)(ignorezeroentries && (addv == ADD_VALUES))));
241         }
242       }
243     }
244   }
245   PetscFunctionReturn(PETSC_SUCCESS);
246 }
247 
248 static PetscErrorCode MatGetValues_MPISELL(Mat mat, PetscInt m, const PetscInt idxm[], PetscInt n, const PetscInt idxn[], PetscScalar v[])
249 {
250   Mat_MPISELL *sell = (Mat_MPISELL *)mat->data;
251   PetscInt     i, j, rstart = mat->rmap->rstart, rend = mat->rmap->rend;
252   PetscInt     cstart = mat->cmap->rstart, cend = mat->cmap->rend, row, col;
253 
254   PetscFunctionBegin;
255   for (i = 0; i < m; i++) {
256     if (idxm[i] < 0) continue; /* negative row */
257     PetscCheck(idxm[i] < mat->rmap->N, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Row too large: row %" PetscInt_FMT " max %" PetscInt_FMT, idxm[i], mat->rmap->N - 1);
258     PetscCheck(idxm[i] >= rstart && idxm[i] < rend, PETSC_COMM_SELF, PETSC_ERR_SUP, "Only local values currently supported");
259     row = idxm[i] - rstart;
260     for (j = 0; j < n; j++) {
261       if (idxn[j] < 0) continue; /* negative column */
262       PetscCheck(idxn[j] < mat->cmap->N, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Column too large: col %" PetscInt_FMT " max %" PetscInt_FMT, idxn[j], mat->cmap->N - 1);
263       if (idxn[j] >= cstart && idxn[j] < cend) {
264         col = idxn[j] - cstart;
265         PetscCall(MatGetValues(sell->A, 1, &row, 1, &col, v + i * n + j));
266       } else {
267         if (!sell->colmap) PetscCall(MatCreateColmap_MPISELL_Private(mat));
268 #if defined(PETSC_USE_CTABLE)
269         PetscCall(PetscHMapIGetWithDefault(sell->colmap, idxn[j] + 1, 0, &col));
270         col--;
271 #else
272         col = sell->colmap[idxn[j]] - 1;
273 #endif
274         if (col < 0 || sell->garray[col] != idxn[j]) *(v + i * n + j) = 0.0;
275         else PetscCall(MatGetValues(sell->B, 1, &row, 1, &col, v + i * n + j));
276       }
277     }
278   }
279   PetscFunctionReturn(PETSC_SUCCESS);
280 }
281 
282 static PetscErrorCode MatAssemblyBegin_MPISELL(Mat mat, MatAssemblyType mode)
283 {
284   Mat_MPISELL *sell = (Mat_MPISELL *)mat->data;
285   PetscInt     nstash, reallocs;
286 
287   PetscFunctionBegin;
288   if (sell->donotstash || mat->nooffprocentries) PetscFunctionReturn(PETSC_SUCCESS);
289 
290   PetscCall(MatStashScatterBegin_Private(mat, &mat->stash, mat->rmap->range));
291   PetscCall(MatStashGetInfo_Private(&mat->stash, &nstash, &reallocs));
292   PetscCall(PetscInfo(sell->A, "Stash has %" PetscInt_FMT " entries, uses %" PetscInt_FMT " mallocs.\n", nstash, reallocs));
293   PetscFunctionReturn(PETSC_SUCCESS);
294 }
295 
296 PetscErrorCode MatAssemblyEnd_MPISELL(Mat mat, MatAssemblyType mode)
297 {
298   Mat_MPISELL *sell = (Mat_MPISELL *)mat->data;
299   PetscMPIInt  n;
300   PetscInt     i, flg;
301   PetscInt    *row, *col;
302   PetscScalar *val;
303   PetscBool    all_assembled;
304   /* do not use 'b = (Mat_SeqSELL*)sell->B->data' as B can be reset in disassembly */
305   PetscFunctionBegin;
306   if (!sell->donotstash && !mat->nooffprocentries) {
307     while (1) {
308       PetscCall(MatStashScatterGetMesg_Private(&mat->stash, &n, &row, &col, &val, &flg));
309       if (!flg) break;
310 
311       for (i = 0; i < n; i++) { /* assemble one by one */
312         PetscCall(MatSetValues_MPISELL(mat, 1, row + i, 1, col + i, val + i, mat->insertmode));
313       }
314     }
315     PetscCall(MatStashScatterEnd_Private(&mat->stash));
316   }
317 #if defined(PETSC_HAVE_CUDA)
318   if (mat->offloadmask == PETSC_OFFLOAD_CPU) sell->A->offloadmask = PETSC_OFFLOAD_CPU;
319 #endif
320   PetscCall(MatAssemblyBegin(sell->A, mode));
321   PetscCall(MatAssemblyEnd(sell->A, mode));
322 
323   /*
324      determine if any process has disassembled, if so we must
325      also disassemble ourselves, in order that we may reassemble.
326   */
327   /*
328      if nonzero structure of submatrix B cannot change then we know that
329      no process disassembled thus we can skip this stuff
330   */
331   if (!((Mat_SeqSELL *)sell->B->data)->nonew) {
332     PetscCallMPI(MPIU_Allreduce(&mat->was_assembled, &all_assembled, 1, MPI_C_BOOL, MPI_LAND, PetscObjectComm((PetscObject)mat)));
333     if (mat->was_assembled && !all_assembled) PetscCall(MatDisAssemble_MPISELL(mat));
334   }
335   if (!mat->was_assembled && mode == MAT_FINAL_ASSEMBLY) PetscCall(MatSetUpMultiply_MPISELL(mat));
336 #if defined(PETSC_HAVE_CUDA)
337   if (mat->offloadmask == PETSC_OFFLOAD_CPU && sell->B->offloadmask != PETSC_OFFLOAD_UNALLOCATED) sell->B->offloadmask = PETSC_OFFLOAD_CPU;
338 #endif
339   PetscCall(MatAssemblyBegin(sell->B, mode));
340   PetscCall(MatAssemblyEnd(sell->B, mode));
341   PetscCall(PetscFree2(sell->rowvalues, sell->rowindices));
342   sell->rowvalues = NULL;
343   PetscCall(VecDestroy(&sell->diag));
344 
345   /* if no new nonzero locations are allowed in matrix then only set the matrix state the first time through */
346   if ((!mat->was_assembled && mode == MAT_FINAL_ASSEMBLY) || !((Mat_SeqSELL *)sell->A->data)->nonew) {
347     PetscObjectState state = sell->A->nonzerostate + sell->B->nonzerostate;
348     PetscCallMPI(MPIU_Allreduce(&state, &mat->nonzerostate, 1, MPIU_INT64, MPI_SUM, PetscObjectComm((PetscObject)mat)));
349   }
350 #if defined(PETSC_HAVE_CUDA)
351   mat->offloadmask = PETSC_OFFLOAD_BOTH;
352 #endif
353   PetscFunctionReturn(PETSC_SUCCESS);
354 }
355 
356 static PetscErrorCode MatZeroEntries_MPISELL(Mat A)
357 {
358   Mat_MPISELL *l = (Mat_MPISELL *)A->data;
359 
360   PetscFunctionBegin;
361   PetscCall(MatZeroEntries(l->A));
362   PetscCall(MatZeroEntries(l->B));
363   PetscFunctionReturn(PETSC_SUCCESS);
364 }
365 
366 static PetscErrorCode MatMult_MPISELL(Mat A, Vec xx, Vec yy)
367 {
368   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
369   PetscInt     nt;
370 
371   PetscFunctionBegin;
372   PetscCall(VecGetLocalSize(xx, &nt));
373   PetscCheck(nt == A->cmap->n, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Incompatible partition of A (%" PetscInt_FMT ") and xx (%" PetscInt_FMT ")", A->cmap->n, nt);
374   PetscCall(VecScatterBegin(a->Mvctx, xx, a->lvec, INSERT_VALUES, SCATTER_FORWARD));
375   PetscCall((*a->A->ops->mult)(a->A, xx, yy));
376   PetscCall(VecScatterEnd(a->Mvctx, xx, a->lvec, INSERT_VALUES, SCATTER_FORWARD));
377   PetscCall((*a->B->ops->multadd)(a->B, a->lvec, yy, yy));
378   PetscFunctionReturn(PETSC_SUCCESS);
379 }
380 
381 static PetscErrorCode MatMultDiagonalBlock_MPISELL(Mat A, Vec bb, Vec xx)
382 {
383   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
384 
385   PetscFunctionBegin;
386   PetscCall(MatMultDiagonalBlock(a->A, bb, xx));
387   PetscFunctionReturn(PETSC_SUCCESS);
388 }
389 
390 static PetscErrorCode MatMultAdd_MPISELL(Mat A, Vec xx, Vec yy, Vec zz)
391 {
392   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
393 
394   PetscFunctionBegin;
395   PetscCall(VecScatterBegin(a->Mvctx, xx, a->lvec, INSERT_VALUES, SCATTER_FORWARD));
396   PetscCall((*a->A->ops->multadd)(a->A, xx, yy, zz));
397   PetscCall(VecScatterEnd(a->Mvctx, xx, a->lvec, INSERT_VALUES, SCATTER_FORWARD));
398   PetscCall((*a->B->ops->multadd)(a->B, a->lvec, zz, zz));
399   PetscFunctionReturn(PETSC_SUCCESS);
400 }
401 
402 static PetscErrorCode MatMultTranspose_MPISELL(Mat A, Vec xx, Vec yy)
403 {
404   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
405 
406   PetscFunctionBegin;
407   /* do nondiagonal part */
408   PetscCall((*a->B->ops->multtranspose)(a->B, xx, a->lvec));
409   /* do local part */
410   PetscCall((*a->A->ops->multtranspose)(a->A, xx, yy));
411   /* add partial results together */
412   PetscCall(VecScatterBegin(a->Mvctx, a->lvec, yy, ADD_VALUES, SCATTER_REVERSE));
413   PetscCall(VecScatterEnd(a->Mvctx, a->lvec, yy, ADD_VALUES, SCATTER_REVERSE));
414   PetscFunctionReturn(PETSC_SUCCESS);
415 }
416 
417 static PetscErrorCode MatIsTranspose_MPISELL(Mat Amat, Mat Bmat, PetscReal tol, PetscBool *f)
418 {
419   MPI_Comm     comm;
420   Mat_MPISELL *Asell = (Mat_MPISELL *)Amat->data, *Bsell;
421   Mat          Adia  = Asell->A, Bdia, Aoff, Boff, *Aoffs, *Boffs;
422   IS           Me, Notme;
423   PetscInt     M, N, first, last, *notme, i;
424   PetscMPIInt  size;
425 
426   PetscFunctionBegin;
427   /* Easy test: symmetric diagonal block */
428   Bsell = (Mat_MPISELL *)Bmat->data;
429   Bdia  = Bsell->A;
430   PetscCall(MatIsTranspose(Adia, Bdia, tol, f));
431   if (!*f) PetscFunctionReturn(PETSC_SUCCESS);
432   PetscCall(PetscObjectGetComm((PetscObject)Amat, &comm));
433   PetscCallMPI(MPI_Comm_size(comm, &size));
434   if (size == 1) PetscFunctionReturn(PETSC_SUCCESS);
435 
436   /* Hard test: off-diagonal block. This takes a MatCreateSubMatrix. */
437   PetscCall(MatGetSize(Amat, &M, &N));
438   PetscCall(MatGetOwnershipRange(Amat, &first, &last));
439   PetscCall(PetscMalloc1(N - last + first, &notme));
440   for (i = 0; i < first; i++) notme[i] = i;
441   for (i = last; i < M; i++) notme[i - last + first] = i;
442   PetscCall(ISCreateGeneral(MPI_COMM_SELF, N - last + first, notme, PETSC_COPY_VALUES, &Notme));
443   PetscCall(ISCreateStride(MPI_COMM_SELF, last - first, first, 1, &Me));
444   PetscCall(MatCreateSubMatrices(Amat, 1, &Me, &Notme, MAT_INITIAL_MATRIX, &Aoffs));
445   Aoff = Aoffs[0];
446   PetscCall(MatCreateSubMatrices(Bmat, 1, &Notme, &Me, MAT_INITIAL_MATRIX, &Boffs));
447   Boff = Boffs[0];
448   PetscCall(MatIsTranspose(Aoff, Boff, tol, f));
449   PetscCall(MatDestroyMatrices(1, &Aoffs));
450   PetscCall(MatDestroyMatrices(1, &Boffs));
451   PetscCall(ISDestroy(&Me));
452   PetscCall(ISDestroy(&Notme));
453   PetscCall(PetscFree(notme));
454   PetscFunctionReturn(PETSC_SUCCESS);
455 }
456 
457 static PetscErrorCode MatMultTransposeAdd_MPISELL(Mat A, Vec xx, Vec yy, Vec zz)
458 {
459   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
460 
461   PetscFunctionBegin;
462   /* do nondiagonal part */
463   PetscCall((*a->B->ops->multtranspose)(a->B, xx, a->lvec));
464   /* do local part */
465   PetscCall((*a->A->ops->multtransposeadd)(a->A, xx, yy, zz));
466   /* add partial results together */
467   PetscCall(VecScatterBegin(a->Mvctx, a->lvec, zz, ADD_VALUES, SCATTER_REVERSE));
468   PetscCall(VecScatterEnd(a->Mvctx, a->lvec, zz, ADD_VALUES, SCATTER_REVERSE));
469   PetscFunctionReturn(PETSC_SUCCESS);
470 }
471 
472 /*
473   This only works correctly for square matrices where the subblock A->A is the
474    diagonal block
475 */
476 static PetscErrorCode MatGetDiagonal_MPISELL(Mat A, Vec v)
477 {
478   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
479 
480   PetscFunctionBegin;
481   PetscCheck(A->rmap->N == A->cmap->N, PetscObjectComm((PetscObject)A), PETSC_ERR_SUP, "Supports only square matrix where A->A is diag block");
482   PetscCheck(A->rmap->rstart == A->cmap->rstart && A->rmap->rend == A->cmap->rend, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "row partition must equal col partition");
483   PetscCall(MatGetDiagonal(a->A, v));
484   PetscFunctionReturn(PETSC_SUCCESS);
485 }
486 
487 static PetscErrorCode MatScale_MPISELL(Mat A, PetscScalar aa)
488 {
489   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
490 
491   PetscFunctionBegin;
492   PetscCall(MatScale(a->A, aa));
493   PetscCall(MatScale(a->B, aa));
494   PetscFunctionReturn(PETSC_SUCCESS);
495 }
496 
497 PetscErrorCode MatDestroy_MPISELL(Mat mat)
498 {
499   Mat_MPISELL *sell = (Mat_MPISELL *)mat->data;
500 
501   PetscFunctionBegin;
502   PetscCall(PetscLogObjectState((PetscObject)mat, "Rows=%" PetscInt_FMT ", Cols=%" PetscInt_FMT, mat->rmap->N, mat->cmap->N));
503   PetscCall(MatStashDestroy_Private(&mat->stash));
504   PetscCall(VecDestroy(&sell->diag));
505   PetscCall(MatDestroy(&sell->A));
506   PetscCall(MatDestroy(&sell->B));
507 #if defined(PETSC_USE_CTABLE)
508   PetscCall(PetscHMapIDestroy(&sell->colmap));
509 #else
510   PetscCall(PetscFree(sell->colmap));
511 #endif
512   PetscCall(PetscFree(sell->garray));
513   PetscCall(VecDestroy(&sell->lvec));
514   PetscCall(VecScatterDestroy(&sell->Mvctx));
515   PetscCall(PetscFree2(sell->rowvalues, sell->rowindices));
516   PetscCall(PetscFree(sell->ld));
517   PetscCall(PetscFree(mat->data));
518 
519   PetscCall(PetscObjectChangeTypeName((PetscObject)mat, NULL));
520   PetscCall(PetscObjectComposeFunction((PetscObject)mat, "MatStoreValues_C", NULL));
521   PetscCall(PetscObjectComposeFunction((PetscObject)mat, "MatRetrieveValues_C", NULL));
522   PetscCall(PetscObjectComposeFunction((PetscObject)mat, "MatIsTranspose_C", NULL));
523   PetscCall(PetscObjectComposeFunction((PetscObject)mat, "MatMPISELLSetPreallocation_C", NULL));
524   PetscCall(PetscObjectComposeFunction((PetscObject)mat, "MatConvert_mpisell_mpiaij_C", NULL));
525 #if defined(PETSC_HAVE_CUDA)
526   PetscCall(PetscObjectComposeFunction((PetscObject)mat, "MatConvert_mpisell_mpisellcuda_C", NULL));
527 #endif
528   PetscCall(PetscObjectComposeFunction((PetscObject)mat, "MatDiagonalScaleLocal_C", NULL));
529   PetscFunctionReturn(PETSC_SUCCESS);
530 }
531 
532 #include <petscdraw.h>
533 static PetscErrorCode MatView_MPISELL_ASCIIorDraworSocket(Mat mat, PetscViewer viewer)
534 {
535   Mat_MPISELL      *sell = (Mat_MPISELL *)mat->data;
536   PetscMPIInt       rank = sell->rank, size = sell->size;
537   PetscBool         isdraw, isascii, isbinary;
538   PetscViewer       sviewer;
539   PetscViewerFormat format;
540 
541   PetscFunctionBegin;
542   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERDRAW, &isdraw));
543   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
544   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
545   if (isascii) {
546     PetscCall(PetscViewerGetFormat(viewer, &format));
547     if (format == PETSC_VIEWER_ASCII_INFO_DETAIL) {
548       MatInfo   info;
549       PetscInt *inodes;
550 
551       PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)mat), &rank));
552       PetscCall(MatGetInfo(mat, MAT_LOCAL, &info));
553       PetscCall(MatInodeGetInodeSizes(sell->A, NULL, &inodes, NULL));
554       PetscCall(PetscViewerASCIIPushSynchronized(viewer));
555       if (!inodes) {
556         PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "[%d] Local rows %" PetscInt_FMT " nz %" PetscInt_FMT " nz alloced %" PetscInt_FMT " mem %" PetscInt_FMT ", not using I-node routines\n", rank, mat->rmap->n, (PetscInt)info.nz_used,
557                                                      (PetscInt)info.nz_allocated, (PetscInt)info.memory));
558       } else {
559         PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "[%d] Local rows %" PetscInt_FMT " nz %" PetscInt_FMT " nz alloced %" PetscInt_FMT " mem %" PetscInt_FMT ", using I-node routines\n", rank, mat->rmap->n, (PetscInt)info.nz_used,
560                                                      (PetscInt)info.nz_allocated, (PetscInt)info.memory));
561       }
562       PetscCall(MatGetInfo(sell->A, MAT_LOCAL, &info));
563       PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "[%d] on-diagonal part: nz %" PetscInt_FMT " \n", rank, (PetscInt)info.nz_used));
564       PetscCall(MatGetInfo(sell->B, MAT_LOCAL, &info));
565       PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "[%d] off-diagonal part: nz %" PetscInt_FMT " \n", rank, (PetscInt)info.nz_used));
566       PetscCall(PetscViewerFlush(viewer));
567       PetscCall(PetscViewerASCIIPopSynchronized(viewer));
568       PetscCall(PetscViewerASCIIPrintf(viewer, "Information on VecScatter used in matrix-vector product: \n"));
569       PetscCall(VecScatterView(sell->Mvctx, viewer));
570       PetscFunctionReturn(PETSC_SUCCESS);
571     } else if (format == PETSC_VIEWER_ASCII_INFO) {
572       PetscInt inodecount, inodelimit, *inodes;
573       PetscCall(MatInodeGetInodeSizes(sell->A, &inodecount, &inodes, &inodelimit));
574       if (inodes) {
575         PetscCall(PetscViewerASCIIPrintf(viewer, "using I-node (on process 0) routines: found %" PetscInt_FMT " nodes, limit used is %" PetscInt_FMT "\n", inodecount, inodelimit));
576       } else {
577         PetscCall(PetscViewerASCIIPrintf(viewer, "not using I-node (on process 0) routines\n"));
578       }
579       PetscFunctionReturn(PETSC_SUCCESS);
580     } else if (format == PETSC_VIEWER_ASCII_FACTOR_INFO) {
581       PetscFunctionReturn(PETSC_SUCCESS);
582     }
583   } else if (isbinary) {
584     if (size == 1) {
585       PetscCall(PetscObjectSetName((PetscObject)sell->A, ((PetscObject)mat)->name));
586       PetscCall(MatView(sell->A, viewer));
587     } else {
588       /* PetscCall(MatView_MPISELL_Binary(mat,viewer)); */
589     }
590     PetscFunctionReturn(PETSC_SUCCESS);
591   } else if (isdraw) {
592     PetscDraw draw;
593     PetscBool isnull;
594     PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
595     PetscCall(PetscDrawIsNull(draw, &isnull));
596     if (isnull) PetscFunctionReturn(PETSC_SUCCESS);
597   }
598 
599   {
600     /* assemble the entire matrix onto first processor. */
601     Mat          A;
602     Mat_SeqSELL *Aloc;
603     PetscInt     M = mat->rmap->N, N = mat->cmap->N, *acolidx, row, col, i, j;
604     MatScalar   *aval;
605     PetscBool    isnonzero;
606 
607     PetscCall(MatCreate(PetscObjectComm((PetscObject)mat), &A));
608     if (rank == 0) {
609       PetscCall(MatSetSizes(A, M, N, M, N));
610     } else {
611       PetscCall(MatSetSizes(A, 0, 0, M, N));
612     }
613     /* This is just a temporary matrix, so explicitly using MATMPISELL is probably best */
614     PetscCall(MatSetType(A, MATMPISELL));
615     PetscCall(MatMPISELLSetPreallocation(A, 0, NULL, 0, NULL));
616     PetscCall(MatSetOption(A, MAT_NEW_NONZERO_LOCATION_ERR, PETSC_FALSE));
617 
618     /* copy over the A part */
619     Aloc    = (Mat_SeqSELL *)sell->A->data;
620     acolidx = Aloc->colidx;
621     aval    = Aloc->val;
622     for (i = 0; i < Aloc->totalslices; i++) { /* loop over slices */
623       for (j = Aloc->sliidx[i]; j < Aloc->sliidx[i + 1]; j++) {
624         isnonzero = (PetscBool)((j - Aloc->sliidx[i]) / Aloc->sliceheight < Aloc->rlen[i * Aloc->sliceheight + j % Aloc->sliceheight]);
625         if (isnonzero) { /* check the mask bit */
626           row = i * Aloc->sliceheight + j % Aloc->sliceheight + mat->rmap->rstart;
627           col = *acolidx + mat->rmap->rstart;
628           PetscCall(MatSetValues(A, 1, &row, 1, &col, aval, INSERT_VALUES));
629         }
630         aval++;
631         acolidx++;
632       }
633     }
634 
635     /* copy over the B part */
636     Aloc    = (Mat_SeqSELL *)sell->B->data;
637     acolidx = Aloc->colidx;
638     aval    = Aloc->val;
639     for (i = 0; i < Aloc->totalslices; i++) {
640       for (j = Aloc->sliidx[i]; j < Aloc->sliidx[i + 1]; j++) {
641         isnonzero = (PetscBool)((j - Aloc->sliidx[i]) / Aloc->sliceheight < Aloc->rlen[i * Aloc->sliceheight + j % Aloc->sliceheight]);
642         if (isnonzero) {
643           row = i * Aloc->sliceheight + j % Aloc->sliceheight + mat->rmap->rstart;
644           col = sell->garray[*acolidx];
645           PetscCall(MatSetValues(A, 1, &row, 1, &col, aval, INSERT_VALUES));
646         }
647         aval++;
648         acolidx++;
649       }
650     }
651 
652     PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
653     PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
654     /*
655        Everyone has to call to draw the matrix since the graphics waits are
656        synchronized across all processors that share the PetscDraw object
657     */
658     PetscCall(PetscViewerGetSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
659     if (rank == 0) {
660       PetscCall(PetscObjectSetName((PetscObject)((Mat_MPISELL *)A->data)->A, ((PetscObject)mat)->name));
661       PetscCall(MatView_SeqSELL(((Mat_MPISELL *)A->data)->A, sviewer));
662     }
663     PetscCall(PetscViewerRestoreSubViewer(viewer, PETSC_COMM_SELF, &sviewer));
664     PetscCall(MatDestroy(&A));
665   }
666   PetscFunctionReturn(PETSC_SUCCESS);
667 }
668 
669 static PetscErrorCode MatView_MPISELL(Mat mat, PetscViewer viewer)
670 {
671   PetscBool isascii, isdraw, issocket, isbinary;
672 
673   PetscFunctionBegin;
674   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
675   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERDRAW, &isdraw));
676   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
677   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSOCKET, &issocket));
678   if (isascii || isdraw || isbinary || issocket) PetscCall(MatView_MPISELL_ASCIIorDraworSocket(mat, viewer));
679   PetscFunctionReturn(PETSC_SUCCESS);
680 }
681 
682 static PetscErrorCode MatGetGhosts_MPISELL(Mat mat, PetscInt *nghosts, const PetscInt *ghosts[])
683 {
684   Mat_MPISELL *sell = (Mat_MPISELL *)mat->data;
685 
686   PetscFunctionBegin;
687   PetscCall(MatGetSize(sell->B, NULL, nghosts));
688   if (ghosts) *ghosts = sell->garray;
689   PetscFunctionReturn(PETSC_SUCCESS);
690 }
691 
692 static PetscErrorCode MatGetInfo_MPISELL(Mat matin, MatInfoType flag, MatInfo *info)
693 {
694   Mat_MPISELL   *mat = (Mat_MPISELL *)matin->data;
695   Mat            A = mat->A, B = mat->B;
696   PetscLogDouble isend[5], irecv[5];
697 
698   PetscFunctionBegin;
699   info->block_size = 1.0;
700   PetscCall(MatGetInfo(A, MAT_LOCAL, info));
701 
702   isend[0] = info->nz_used;
703   isend[1] = info->nz_allocated;
704   isend[2] = info->nz_unneeded;
705   isend[3] = info->memory;
706   isend[4] = info->mallocs;
707 
708   PetscCall(MatGetInfo(B, MAT_LOCAL, info));
709 
710   isend[0] += info->nz_used;
711   isend[1] += info->nz_allocated;
712   isend[2] += info->nz_unneeded;
713   isend[3] += info->memory;
714   isend[4] += info->mallocs;
715   if (flag == MAT_LOCAL) {
716     info->nz_used      = isend[0];
717     info->nz_allocated = isend[1];
718     info->nz_unneeded  = isend[2];
719     info->memory       = isend[3];
720     info->mallocs      = isend[4];
721   } else if (flag == MAT_GLOBAL_MAX) {
722     PetscCallMPI(MPIU_Allreduce(isend, irecv, 5, MPIU_PETSCLOGDOUBLE, MPI_MAX, PetscObjectComm((PetscObject)matin)));
723 
724     info->nz_used      = irecv[0];
725     info->nz_allocated = irecv[1];
726     info->nz_unneeded  = irecv[2];
727     info->memory       = irecv[3];
728     info->mallocs      = irecv[4];
729   } else if (flag == MAT_GLOBAL_SUM) {
730     PetscCallMPI(MPIU_Allreduce(isend, irecv, 5, MPIU_PETSCLOGDOUBLE, MPI_SUM, PetscObjectComm((PetscObject)matin)));
731 
732     info->nz_used      = irecv[0];
733     info->nz_allocated = irecv[1];
734     info->nz_unneeded  = irecv[2];
735     info->memory       = irecv[3];
736     info->mallocs      = irecv[4];
737   }
738   info->fill_ratio_given  = 0; /* no parallel LU/ILU/Cholesky */
739   info->fill_ratio_needed = 0;
740   info->factor_mallocs    = 0;
741   PetscFunctionReturn(PETSC_SUCCESS);
742 }
743 
744 static PetscErrorCode MatSetOption_MPISELL(Mat A, MatOption op, PetscBool flg)
745 {
746   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
747 
748   PetscFunctionBegin;
749   switch (op) {
750   case MAT_NEW_NONZERO_LOCATIONS:
751   case MAT_NEW_NONZERO_ALLOCATION_ERR:
752   case MAT_UNUSED_NONZERO_LOCATION_ERR:
753   case MAT_KEEP_NONZERO_PATTERN:
754   case MAT_NEW_NONZERO_LOCATION_ERR:
755   case MAT_USE_INODES:
756   case MAT_IGNORE_ZERO_ENTRIES:
757     MatCheckPreallocated(A, 1);
758     PetscCall(MatSetOption(a->A, op, flg));
759     PetscCall(MatSetOption(a->B, op, flg));
760     break;
761   case MAT_ROW_ORIENTED:
762     MatCheckPreallocated(A, 1);
763     a->roworiented = flg;
764 
765     PetscCall(MatSetOption(a->A, op, flg));
766     PetscCall(MatSetOption(a->B, op, flg));
767     break;
768   case MAT_IGNORE_OFF_PROC_ENTRIES:
769     a->donotstash = flg;
770     break;
771   case MAT_SYMMETRIC:
772     MatCheckPreallocated(A, 1);
773     PetscCall(MatSetOption(a->A, op, flg));
774     break;
775   case MAT_STRUCTURALLY_SYMMETRIC:
776     MatCheckPreallocated(A, 1);
777     PetscCall(MatSetOption(a->A, op, flg));
778     break;
779   case MAT_HERMITIAN:
780     MatCheckPreallocated(A, 1);
781     PetscCall(MatSetOption(a->A, op, flg));
782     break;
783   case MAT_SYMMETRY_ETERNAL:
784     MatCheckPreallocated(A, 1);
785     PetscCall(MatSetOption(a->A, op, flg));
786     break;
787   case MAT_STRUCTURAL_SYMMETRY_ETERNAL:
788     MatCheckPreallocated(A, 1);
789     PetscCall(MatSetOption(a->A, op, flg));
790     break;
791   default:
792     break;
793   }
794   PetscFunctionReturn(PETSC_SUCCESS);
795 }
796 
797 static PetscErrorCode MatDiagonalScale_MPISELL(Mat mat, Vec ll, Vec rr)
798 {
799   Mat_MPISELL *sell = (Mat_MPISELL *)mat->data;
800   Mat          a = sell->A, b = sell->B;
801   PetscInt     s1, s2, s3;
802 
803   PetscFunctionBegin;
804   PetscCall(MatGetLocalSize(mat, &s2, &s3));
805   if (rr) {
806     PetscCall(VecGetLocalSize(rr, &s1));
807     PetscCheck(s1 == s3, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "right vector non-conforming local size");
808     /* Overlap communication with computation. */
809     PetscCall(VecScatterBegin(sell->Mvctx, rr, sell->lvec, INSERT_VALUES, SCATTER_FORWARD));
810   }
811   if (ll) {
812     PetscCall(VecGetLocalSize(ll, &s1));
813     PetscCheck(s1 == s2, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "left vector non-conforming local size");
814     PetscUseTypeMethod(b, diagonalscale, ll, NULL);
815   }
816   /* scale  the diagonal block */
817   PetscUseTypeMethod(a, diagonalscale, ll, rr);
818 
819   if (rr) {
820     /* Do a scatter end and then right scale the off-diagonal block */
821     PetscCall(VecScatterEnd(sell->Mvctx, rr, sell->lvec, INSERT_VALUES, SCATTER_FORWARD));
822     PetscUseTypeMethod(b, diagonalscale, NULL, sell->lvec);
823   }
824   PetscFunctionReturn(PETSC_SUCCESS);
825 }
826 
827 static PetscErrorCode MatSetUnfactored_MPISELL(Mat A)
828 {
829   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
830 
831   PetscFunctionBegin;
832   PetscCall(MatSetUnfactored(a->A));
833   PetscFunctionReturn(PETSC_SUCCESS);
834 }
835 
836 static PetscErrorCode MatEqual_MPISELL(Mat A, Mat B, PetscBool *flag)
837 {
838   Mat_MPISELL *matB = (Mat_MPISELL *)B->data, *matA = (Mat_MPISELL *)A->data;
839   Mat          a, b, c, d;
840   PetscBool    flg;
841 
842   PetscFunctionBegin;
843   a = matA->A;
844   b = matA->B;
845   c = matB->A;
846   d = matB->B;
847 
848   PetscCall(MatEqual(a, c, &flg));
849   if (flg) PetscCall(MatEqual(b, d, &flg));
850   PetscCallMPI(MPIU_Allreduce(&flg, flag, 1, MPI_C_BOOL, MPI_LAND, PetscObjectComm((PetscObject)A)));
851   PetscFunctionReturn(PETSC_SUCCESS);
852 }
853 
854 static PetscErrorCode MatCopy_MPISELL(Mat A, Mat B, MatStructure str)
855 {
856   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
857   Mat_MPISELL *b = (Mat_MPISELL *)B->data;
858 
859   PetscFunctionBegin;
860   /* If the two matrices don't have the same copy implementation, they aren't compatible for fast copy. */
861   if ((str != SAME_NONZERO_PATTERN) || (A->ops->copy != B->ops->copy)) {
862     /* because of the column compression in the off-processor part of the matrix a->B,
863        the number of columns in a->B and b->B may be different, hence we cannot call
864        the MatCopy() directly on the two parts. If need be, we can provide a more
865        efficient copy than the MatCopy_Basic() by first uncompressing the a->B matrices
866        then copying the submatrices */
867     PetscCall(MatCopy_Basic(A, B, str));
868   } else {
869     PetscCall(MatCopy(a->A, b->A, str));
870     PetscCall(MatCopy(a->B, b->B, str));
871   }
872   PetscFunctionReturn(PETSC_SUCCESS);
873 }
874 
875 static PetscErrorCode MatSetUp_MPISELL(Mat A)
876 {
877   PetscFunctionBegin;
878   PetscCall(MatMPISELLSetPreallocation(A, PETSC_DEFAULT, NULL, PETSC_DEFAULT, NULL));
879   PetscFunctionReturn(PETSC_SUCCESS);
880 }
881 
882 static PetscErrorCode MatConjugate_MPISELL(Mat mat)
883 {
884   PetscFunctionBegin;
885   if (PetscDefined(USE_COMPLEX)) {
886     Mat_MPISELL *sell = (Mat_MPISELL *)mat->data;
887 
888     PetscCall(MatConjugate_SeqSELL(sell->A));
889     PetscCall(MatConjugate_SeqSELL(sell->B));
890   }
891   PetscFunctionReturn(PETSC_SUCCESS);
892 }
893 
894 static PetscErrorCode MatRealPart_MPISELL(Mat A)
895 {
896   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
897 
898   PetscFunctionBegin;
899   PetscCall(MatRealPart(a->A));
900   PetscCall(MatRealPart(a->B));
901   PetscFunctionReturn(PETSC_SUCCESS);
902 }
903 
904 static PetscErrorCode MatImaginaryPart_MPISELL(Mat A)
905 {
906   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
907 
908   PetscFunctionBegin;
909   PetscCall(MatImaginaryPart(a->A));
910   PetscCall(MatImaginaryPart(a->B));
911   PetscFunctionReturn(PETSC_SUCCESS);
912 }
913 
914 static PetscErrorCode MatInvertBlockDiagonal_MPISELL(Mat A, const PetscScalar **values)
915 {
916   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
917 
918   PetscFunctionBegin;
919   PetscCall(MatInvertBlockDiagonal(a->A, values));
920   A->factorerrortype = a->A->factorerrortype;
921   PetscFunctionReturn(PETSC_SUCCESS);
922 }
923 
924 static PetscErrorCode MatSetRandom_MPISELL(Mat x, PetscRandom rctx)
925 {
926   Mat_MPISELL *sell = (Mat_MPISELL *)x->data;
927 
928   PetscFunctionBegin;
929   PetscCall(MatSetRandom(sell->A, rctx));
930   PetscCall(MatSetRandom(sell->B, rctx));
931   PetscCall(MatAssemblyBegin(x, MAT_FINAL_ASSEMBLY));
932   PetscCall(MatAssemblyEnd(x, MAT_FINAL_ASSEMBLY));
933   PetscFunctionReturn(PETSC_SUCCESS);
934 }
935 
936 static PetscErrorCode MatSetFromOptions_MPISELL(Mat A, PetscOptionItems PetscOptionsObject)
937 {
938   PetscFunctionBegin;
939   PetscOptionsHeadBegin(PetscOptionsObject, "MPISELL options");
940   PetscOptionsHeadEnd();
941   PetscFunctionReturn(PETSC_SUCCESS);
942 }
943 
944 static PetscErrorCode MatShift_MPISELL(Mat Y, PetscScalar a)
945 {
946   Mat_MPISELL *msell = (Mat_MPISELL *)Y->data;
947   Mat_SeqSELL *sell  = (Mat_SeqSELL *)msell->A->data;
948 
949   PetscFunctionBegin;
950   if (!Y->preallocated) {
951     PetscCall(MatMPISELLSetPreallocation(Y, 1, NULL, 0, NULL));
952   } else if (!sell->nz) {
953     PetscInt nonew = sell->nonew;
954     PetscCall(MatSeqSELLSetPreallocation(msell->A, 1, NULL));
955     sell->nonew = nonew;
956   }
957   PetscCall(MatShift_Basic(Y, a));
958   PetscFunctionReturn(PETSC_SUCCESS);
959 }
960 
961 static PetscErrorCode MatGetDiagonalBlock_MPISELL(Mat A, Mat *a)
962 {
963   PetscFunctionBegin;
964   *a = ((Mat_MPISELL *)A->data)->A;
965   PetscFunctionReturn(PETSC_SUCCESS);
966 }
967 
968 static PetscErrorCode MatStoreValues_MPISELL(Mat mat)
969 {
970   Mat_MPISELL *sell = (Mat_MPISELL *)mat->data;
971 
972   PetscFunctionBegin;
973   PetscCall(MatStoreValues(sell->A));
974   PetscCall(MatStoreValues(sell->B));
975   PetscFunctionReturn(PETSC_SUCCESS);
976 }
977 
978 static PetscErrorCode MatRetrieveValues_MPISELL(Mat mat)
979 {
980   Mat_MPISELL *sell = (Mat_MPISELL *)mat->data;
981 
982   PetscFunctionBegin;
983   PetscCall(MatRetrieveValues(sell->A));
984   PetscCall(MatRetrieveValues(sell->B));
985   PetscFunctionReturn(PETSC_SUCCESS);
986 }
987 
988 static PetscErrorCode MatMPISELLSetPreallocation_MPISELL(Mat B, PetscInt d_rlenmax, const PetscInt d_rlen[], PetscInt o_rlenmax, const PetscInt o_rlen[])
989 {
990   Mat_MPISELL *b;
991 
992   PetscFunctionBegin;
993   PetscCall(PetscLayoutSetUp(B->rmap));
994   PetscCall(PetscLayoutSetUp(B->cmap));
995   b = (Mat_MPISELL *)B->data;
996 
997   if (!B->preallocated) {
998     /* Explicitly create 2 MATSEQSELL matrices. */
999     PetscCall(MatCreate(PETSC_COMM_SELF, &b->A));
1000     PetscCall(MatSetSizes(b->A, B->rmap->n, B->cmap->n, B->rmap->n, B->cmap->n));
1001     PetscCall(MatSetBlockSizesFromMats(b->A, B, B));
1002     PetscCall(MatSetType(b->A, MATSEQSELL));
1003     PetscCall(MatCreate(PETSC_COMM_SELF, &b->B));
1004     PetscCall(MatSetSizes(b->B, B->rmap->n, B->cmap->N, B->rmap->n, B->cmap->N));
1005     PetscCall(MatSetBlockSizesFromMats(b->B, B, B));
1006     PetscCall(MatSetType(b->B, MATSEQSELL));
1007   }
1008 
1009   PetscCall(MatSeqSELLSetPreallocation(b->A, d_rlenmax, d_rlen));
1010   PetscCall(MatSeqSELLSetPreallocation(b->B, o_rlenmax, o_rlen));
1011   B->preallocated  = PETSC_TRUE;
1012   B->was_assembled = PETSC_FALSE;
1013   /*
1014     critical for MatAssemblyEnd to work.
1015     MatAssemblyBegin checks it to set up was_assembled
1016     and MatAssemblyEnd checks was_assembled to determine whether to build garray
1017   */
1018   B->assembled = PETSC_FALSE;
1019   PetscFunctionReturn(PETSC_SUCCESS);
1020 }
1021 
1022 static PetscErrorCode MatDuplicate_MPISELL(Mat matin, MatDuplicateOption cpvalues, Mat *newmat)
1023 {
1024   Mat          mat;
1025   Mat_MPISELL *a, *oldmat = (Mat_MPISELL *)matin->data;
1026 
1027   PetscFunctionBegin;
1028   *newmat = NULL;
1029   PetscCall(MatCreate(PetscObjectComm((PetscObject)matin), &mat));
1030   PetscCall(MatSetSizes(mat, matin->rmap->n, matin->cmap->n, matin->rmap->N, matin->cmap->N));
1031   PetscCall(MatSetBlockSizesFromMats(mat, matin, matin));
1032   PetscCall(MatSetType(mat, ((PetscObject)matin)->type_name));
1033   a = (Mat_MPISELL *)mat->data;
1034 
1035   mat->factortype   = matin->factortype;
1036   mat->assembled    = PETSC_TRUE;
1037   mat->insertmode   = NOT_SET_VALUES;
1038   mat->preallocated = PETSC_TRUE;
1039 
1040   a->size         = oldmat->size;
1041   a->rank         = oldmat->rank;
1042   a->donotstash   = oldmat->donotstash;
1043   a->roworiented  = oldmat->roworiented;
1044   a->rowindices   = NULL;
1045   a->rowvalues    = NULL;
1046   a->getrowactive = PETSC_FALSE;
1047 
1048   PetscCall(PetscLayoutReference(matin->rmap, &mat->rmap));
1049   PetscCall(PetscLayoutReference(matin->cmap, &mat->cmap));
1050 
1051   if (oldmat->colmap) {
1052 #if defined(PETSC_USE_CTABLE)
1053     PetscCall(PetscHMapIDuplicate(oldmat->colmap, &a->colmap));
1054 #else
1055     PetscCall(PetscMalloc1(mat->cmap->N, &a->colmap));
1056     PetscCall(PetscArraycpy(a->colmap, oldmat->colmap, mat->cmap->N));
1057 #endif
1058   } else a->colmap = NULL;
1059   if (oldmat->garray) {
1060     PetscInt len;
1061     len = oldmat->B->cmap->n;
1062     PetscCall(PetscMalloc1(len + 1, &a->garray));
1063     if (len) PetscCall(PetscArraycpy(a->garray, oldmat->garray, len));
1064   } else a->garray = NULL;
1065 
1066   PetscCall(VecDuplicate(oldmat->lvec, &a->lvec));
1067   PetscCall(VecScatterCopy(oldmat->Mvctx, &a->Mvctx));
1068   PetscCall(MatDuplicate(oldmat->A, cpvalues, &a->A));
1069   PetscCall(MatDuplicate(oldmat->B, cpvalues, &a->B));
1070   PetscCall(PetscFunctionListDuplicate(((PetscObject)matin)->qlist, &((PetscObject)mat)->qlist));
1071   *newmat = mat;
1072   PetscFunctionReturn(PETSC_SUCCESS);
1073 }
1074 
1075 static const struct _MatOps MatOps_Values = {MatSetValues_MPISELL,
1076                                              NULL,
1077                                              NULL,
1078                                              MatMult_MPISELL,
1079                                              /* 4*/ MatMultAdd_MPISELL,
1080                                              MatMultTranspose_MPISELL,
1081                                              MatMultTransposeAdd_MPISELL,
1082                                              NULL,
1083                                              NULL,
1084                                              NULL,
1085                                              /*10*/ NULL,
1086                                              NULL,
1087                                              NULL,
1088                                              MatSOR_MPISELL,
1089                                              NULL,
1090                                              /*15*/ MatGetInfo_MPISELL,
1091                                              MatEqual_MPISELL,
1092                                              MatGetDiagonal_MPISELL,
1093                                              MatDiagonalScale_MPISELL,
1094                                              NULL,
1095                                              /*20*/ MatAssemblyBegin_MPISELL,
1096                                              MatAssemblyEnd_MPISELL,
1097                                              MatSetOption_MPISELL,
1098                                              MatZeroEntries_MPISELL,
1099                                              /*24*/ NULL,
1100                                              NULL,
1101                                              NULL,
1102                                              NULL,
1103                                              NULL,
1104                                              /*29*/ MatSetUp_MPISELL,
1105                                              NULL,
1106                                              NULL,
1107                                              MatGetDiagonalBlock_MPISELL,
1108                                              NULL,
1109                                              /*34*/ MatDuplicate_MPISELL,
1110                                              NULL,
1111                                              NULL,
1112                                              NULL,
1113                                              NULL,
1114                                              /*39*/ NULL,
1115                                              NULL,
1116                                              NULL,
1117                                              MatGetValues_MPISELL,
1118                                              MatCopy_MPISELL,
1119                                              /*44*/ NULL,
1120                                              MatScale_MPISELL,
1121                                              MatShift_MPISELL,
1122                                              MatDiagonalSet_MPISELL,
1123                                              NULL,
1124                                              /*49*/ MatSetRandom_MPISELL,
1125                                              NULL,
1126                                              NULL,
1127                                              NULL,
1128                                              NULL,
1129                                              /*54*/ MatFDColoringCreate_MPIXAIJ,
1130                                              NULL,
1131                                              MatSetUnfactored_MPISELL,
1132                                              NULL,
1133                                              NULL,
1134                                              /*59*/ NULL,
1135                                              MatDestroy_MPISELL,
1136                                              MatView_MPISELL,
1137                                              NULL,
1138                                              NULL,
1139                                              /*64*/ NULL,
1140                                              NULL,
1141                                              NULL,
1142                                              NULL,
1143                                              NULL,
1144                                              /*69*/ NULL,
1145                                              NULL,
1146                                              NULL,
1147                                              MatFDColoringApply_AIJ, /* reuse AIJ function */
1148                                              MatSetFromOptions_MPISELL,
1149                                              NULL,
1150                                              /*75*/ NULL,
1151                                              NULL,
1152                                              NULL,
1153                                              NULL,
1154                                              NULL,
1155                                              /*80*/ NULL,
1156                                              NULL,
1157                                              NULL,
1158                                              /*83*/ NULL,
1159                                              NULL,
1160                                              NULL,
1161                                              NULL,
1162                                              NULL,
1163                                              NULL,
1164                                              /*89*/ NULL,
1165                                              NULL,
1166                                              NULL,
1167                                              NULL,
1168                                              MatConjugate_MPISELL,
1169                                              /*94*/ NULL,
1170                                              NULL,
1171                                              MatRealPart_MPISELL,
1172                                              MatImaginaryPart_MPISELL,
1173                                              NULL,
1174                                              /*99*/ NULL,
1175                                              NULL,
1176                                              NULL,
1177                                              NULL,
1178                                              NULL,
1179                                              /*104*/ NULL,
1180                                              NULL,
1181                                              MatGetGhosts_MPISELL,
1182                                              NULL,
1183                                              NULL,
1184                                              /*109*/ MatMultDiagonalBlock_MPISELL,
1185                                              NULL,
1186                                              NULL,
1187                                              NULL,
1188                                              NULL,
1189                                              /*114*/ NULL,
1190                                              NULL,
1191                                              MatInvertBlockDiagonal_MPISELL,
1192                                              NULL,
1193                                              /*119*/ NULL,
1194                                              NULL,
1195                                              NULL,
1196                                              NULL,
1197                                              NULL,
1198                                              /*124*/ NULL,
1199                                              NULL,
1200                                              NULL,
1201                                              NULL,
1202                                              NULL,
1203                                              /*129*/ MatFDColoringSetUp_MPIXAIJ,
1204                                              NULL,
1205                                              NULL,
1206                                              NULL,
1207                                              NULL,
1208                                              /*134*/ NULL,
1209                                              NULL,
1210                                              NULL,
1211                                              NULL,
1212                                              NULL,
1213                                              /*139*/ NULL,
1214                                              NULL,
1215                                              NULL,
1216                                              NULL,
1217                                              NULL,
1218                                              NULL};
1219 
1220 /*@C
1221   MatMPISELLSetPreallocation - Preallocates memory for a `MATMPISELL` sparse parallel matrix in sell format.
1222   For good matrix assembly performance the user should preallocate the matrix storage by
1223   setting the parameters `d_nz` (or `d_nnz`) and `o_nz` (or `o_nnz`).
1224 
1225   Collective
1226 
1227   Input Parameters:
1228 + B     - the matrix
1229 . d_nz  - number of nonzeros per row in DIAGONAL portion of local submatrix
1230            (same value is used for all local rows)
1231 . d_nnz - array containing the number of nonzeros in the various rows of the
1232            DIAGONAL portion of the local submatrix (possibly different for each row)
1233            or NULL (`PETSC_NULL_INTEGER` in Fortran), if `d_nz` is used to specify the nonzero structure.
1234            The size of this array is equal to the number of local rows, i.e 'm'.
1235            For matrices that will be factored, you must leave room for (and set)
1236            the diagonal entry even if it is zero.
1237 . o_nz  - number of nonzeros per row in the OFF-DIAGONAL portion of local
1238            submatrix (same value is used for all local rows).
1239 - o_nnz - array containing the number of nonzeros in the various rows of the
1240            OFF-DIAGONAL portion of the local submatrix (possibly different for
1241            each row) or NULL (`PETSC_NULL_INTEGER` in Fortran), if `o_nz` is used to specify the nonzero
1242            structure. The size of this array is equal to the number
1243            of local rows, i.e 'm'.
1244 
1245   Example usage:
1246   Consider the following 8x8 matrix with 34 non-zero values, that is
1247   assembled across 3 processors. Lets assume that proc0 owns 3 rows,
1248   proc1 owns 3 rows, proc2 owns 2 rows. This division can be shown
1249   as follows
1250 
1251 .vb
1252             1  2  0  |  0  3  0  |  0  4
1253     Proc0   0  5  6  |  7  0  0  |  8  0
1254             9  0 10  | 11  0  0  | 12  0
1255     -------------------------------------
1256            13  0 14  | 15 16 17  |  0  0
1257     Proc1   0 18  0  | 19 20 21  |  0  0
1258             0  0  0  | 22 23  0  | 24  0
1259     -------------------------------------
1260     Proc2  25 26 27  |  0  0 28  | 29  0
1261            30  0  0  | 31 32 33  |  0 34
1262 .ve
1263 
1264   This can be represented as a collection of submatrices as
1265 
1266 .vb
1267       A B C
1268       D E F
1269       G H I
1270 .ve
1271 
1272   Where the submatrices A,B,C are owned by proc0, D,E,F are
1273   owned by proc1, G,H,I are owned by proc2.
1274 
1275   The 'm' parameters for proc0,proc1,proc2 are 3,3,2 respectively.
1276   The 'n' parameters for proc0,proc1,proc2 are 3,3,2 respectively.
1277   The 'M','N' parameters are 8,8, and have the same values on all procs.
1278 
1279   The DIAGONAL submatrices corresponding to proc0,proc1,proc2 are
1280   submatrices [A], [E], [I] respectively. The OFF-DIAGONAL submatrices
1281   corresponding to proc0,proc1,proc2 are [BC], [DF], [GH] respectively.
1282   Internally, each processor stores the DIAGONAL part, and the OFF-DIAGONAL
1283   part as `MATSEQSELL` matrices. For example, proc1 will store [E] as a `MATSEQSELL`
1284   matrix, and [DF] as another SeqSELL matrix.
1285 
1286   When `d_nz`, `o_nz` parameters are specified, `d_nz` storage elements are
1287   allocated for every row of the local DIAGONAL submatrix, and o_nz
1288   storage locations are allocated for every row of the OFF-DIAGONAL submatrix.
1289   One way to choose `d_nz` and `o_nz` is to use the maximum number of nonzeros over
1290   the local rows for each of the local DIAGONAL, and the OFF-DIAGONAL submatrices.
1291   In this case, the values of d_nz,o_nz are
1292 .vb
1293      proc0  dnz = 2, o_nz = 2
1294      proc1  dnz = 3, o_nz = 2
1295      proc2  dnz = 1, o_nz = 4
1296 .ve
1297   We are allocating m*(d_nz+o_nz) storage locations for every proc. This
1298   translates to 3*(2+2)=12 for proc0, 3*(3+2)=15 for proc1, 2*(1+4)=10
1299   for proc3. i.e we are using 12+15+10=37 storage locations to store
1300   34 values.
1301 
1302   When `d_nnz`, `o_nnz` parameters are specified, the storage is specified
1303   for every row, corresponding to both DIAGONAL and OFF-DIAGONAL submatrices.
1304   In the above case the values for d_nnz,o_nnz are
1305 .vb
1306      proc0 d_nnz = [2,2,2] and o_nnz = [2,2,2]
1307      proc1 d_nnz = [3,3,2] and o_nnz = [2,1,1]
1308      proc2 d_nnz = [1,1]   and o_nnz = [4,4]
1309 .ve
1310   Here the space allocated is according to nz (or maximum values in the nnz
1311   if nnz is provided) for DIAGONAL and OFF-DIAGONAL submatrices, i.e (2+2+3+2)*3+(1+4)*2=37
1312 
1313   Level: intermediate
1314 
1315   Notes:
1316   If the *_nnz parameter is given then the *_nz parameter is ignored
1317 
1318   The stored row and column indices begin with zero.
1319 
1320   The parallel matrix is partitioned such that the first m0 rows belong to
1321   process 0, the next m1 rows belong to process 1, the next m2 rows belong
1322   to process 2 etc.. where m0,m1,m2... are the input parameter 'm'.
1323 
1324   The DIAGONAL portion of the local submatrix of a processor can be defined
1325   as the submatrix which is obtained by extraction the part corresponding to
1326   the rows r1-r2 and columns c1-c2 of the global matrix, where r1 is the
1327   first row that belongs to the processor, r2 is the last row belonging to
1328   the this processor, and c1-c2 is range of indices of the local part of a
1329   vector suitable for applying the matrix to.  This is an mxn matrix.  In the
1330   common case of a square matrix, the row and column ranges are the same and
1331   the DIAGONAL part is also square. The remaining portion of the local
1332   submatrix (mxN) constitute the OFF-DIAGONAL portion.
1333 
1334   If `o_nnz`, `d_nnz` are specified, then `o_nz`, and `d_nz` are ignored.
1335 
1336   You can call `MatGetInfo()` to get information on how effective the preallocation was;
1337   for example the fields mallocs,nz_allocated,nz_used,nz_unneeded;
1338   You can also run with the option -info and look for messages with the string
1339   malloc in them to see if additional memory allocation was needed.
1340 
1341 .seealso: `Mat`, `MatCreate()`, `MatCreateSeqSELL()`, `MatSetValues()`, `MatCreateSELL()`,
1342           `MATMPISELL`, `MatGetInfo()`, `PetscSplitOwnership()`, `MATSELL`
1343 @*/
1344 PetscErrorCode MatMPISELLSetPreallocation(Mat B, PetscInt d_nz, const PetscInt d_nnz[], PetscInt o_nz, const PetscInt o_nnz[])
1345 {
1346   PetscFunctionBegin;
1347   PetscValidHeaderSpecific(B, MAT_CLASSID, 1);
1348   PetscValidType(B, 1);
1349   PetscTryMethod(B, "MatMPISELLSetPreallocation_C", (Mat, PetscInt, const PetscInt[], PetscInt, const PetscInt[]), (B, d_nz, d_nnz, o_nz, o_nnz));
1350   PetscFunctionReturn(PETSC_SUCCESS);
1351 }
1352 
1353 /*MC
1354    MATMPISELL - MATMPISELL = "mpisell" - A matrix type to be used for MPI sparse matrices,
1355    based on the sliced Ellpack format
1356 
1357    Options Database Key:
1358 . -mat_type sell - sets the matrix type to `MATSELL` during a call to `MatSetFromOptions()`
1359 
1360    Level: beginner
1361 
1362 .seealso: `Mat`, `MatCreateSELL()`, `MATSEQSELL`, `MATSELL`, `MATSEQAIJ`, `MATAIJ`, `MATMPIAIJ`
1363 M*/
1364 
1365 /*@C
1366   MatCreateSELL - Creates a sparse parallel matrix in `MATSELL` format.
1367 
1368   Collective
1369 
1370   Input Parameters:
1371 + comm      - MPI communicator
1372 . m         - number of local rows (or `PETSC_DECIDE` to have calculated if M is given)
1373               This value should be the same as the local size used in creating the
1374               y vector for the matrix-vector product y = Ax.
1375 . n         - This value should be the same as the local size used in creating the
1376               x vector for the matrix-vector product y = Ax. (or `PETSC_DECIDE` to have
1377               calculated if `N` is given) For square matrices n is almost always `m`.
1378 . M         - number of global rows (or `PETSC_DETERMINE` to have calculated if `m` is given)
1379 . N         - number of global columns (or `PETSC_DETERMINE` to have calculated if `n` is given)
1380 . d_rlenmax - max number of nonzeros per row in DIAGONAL portion of local submatrix
1381              (same value is used for all local rows)
1382 . d_rlen    - array containing the number of nonzeros in the various rows of the
1383               DIAGONAL portion of the local submatrix (possibly different for each row)
1384               or `NULL`, if d_rlenmax is used to specify the nonzero structure.
1385               The size of this array is equal to the number of local rows, i.e `m`.
1386 . o_rlenmax - max number of nonzeros per row in the OFF-DIAGONAL portion of local
1387               submatrix (same value is used for all local rows).
1388 - o_rlen    - array containing the number of nonzeros in the various rows of the
1389               OFF-DIAGONAL portion of the local submatrix (possibly different for
1390               each row) or `NULL`, if `o_rlenmax` is used to specify the nonzero
1391               structure. The size of this array is equal to the number
1392               of local rows, i.e `m`.
1393 
1394   Output Parameter:
1395 . A - the matrix
1396 
1397   Options Database Key:
1398 . -mat_sell_oneindex - Internally use indexing starting at 1
1399         rather than 0.  When calling `MatSetValues()`,
1400         the user still MUST index entries starting at 0!
1401 
1402   Example:
1403   Consider the following 8x8 matrix with 34 non-zero values, that is
1404   assembled across 3 processors. Lets assume that proc0 owns 3 rows,
1405   proc1 owns 3 rows, proc2 owns 2 rows. This division can be shown
1406   as follows
1407 
1408 .vb
1409             1  2  0  |  0  3  0  |  0  4
1410     Proc0   0  5  6  |  7  0  0  |  8  0
1411             9  0 10  | 11  0  0  | 12  0
1412     -------------------------------------
1413            13  0 14  | 15 16 17  |  0  0
1414     Proc1   0 18  0  | 19 20 21  |  0  0
1415             0  0  0  | 22 23  0  | 24  0
1416     -------------------------------------
1417     Proc2  25 26 27  |  0  0 28  | 29  0
1418            30  0  0  | 31 32 33  |  0 34
1419 .ve
1420 
1421   This can be represented as a collection of submatrices as
1422 .vb
1423       A B C
1424       D E F
1425       G H I
1426 .ve
1427 
1428   Where the submatrices A,B,C are owned by proc0, D,E,F are
1429   owned by proc1, G,H,I are owned by proc2.
1430 
1431   The 'm' parameters for proc0,proc1,proc2 are 3,3,2 respectively.
1432   The 'n' parameters for proc0,proc1,proc2 are 3,3,2 respectively.
1433   The 'M','N' parameters are 8,8, and have the same values on all procs.
1434 
1435   The DIAGONAL submatrices corresponding to proc0,proc1,proc2 are
1436   submatrices [A], [E], [I] respectively. The OFF-DIAGONAL submatrices
1437   corresponding to proc0,proc1,proc2 are [BC], [DF], [GH] respectively.
1438   Internally, each processor stores the DIAGONAL part, and the OFF-DIAGONAL
1439   part as `MATSEQSELL` matrices. For example, proc1 will store [E] as a `MATSEQSELL`
1440   matrix, and [DF] as another `MATSEQSELL` matrix.
1441 
1442   When d_rlenmax, o_rlenmax parameters are specified, d_rlenmax storage elements are
1443   allocated for every row of the local DIAGONAL submatrix, and o_rlenmax
1444   storage locations are allocated for every row of the OFF-DIAGONAL submatrix.
1445   One way to choose `d_rlenmax` and `o_rlenmax` is to use the maximum number of nonzeros over
1446   the local rows for each of the local DIAGONAL, and the OFF-DIAGONAL submatrices.
1447   In this case, the values of d_rlenmax,o_rlenmax are
1448 .vb
1449      proc0 - d_rlenmax = 2, o_rlenmax = 2
1450      proc1 - d_rlenmax = 3, o_rlenmax = 2
1451      proc2 - d_rlenmax = 1, o_rlenmax = 4
1452 .ve
1453   We are allocating m*(d_rlenmax+o_rlenmax) storage locations for every proc. This
1454   translates to 3*(2+2)=12 for proc0, 3*(3+2)=15 for proc1, 2*(1+4)=10
1455   for proc3. i.e we are using 12+15+10=37 storage locations to store
1456   34 values.
1457 
1458   When `d_rlen`, `o_rlen` parameters are specified, the storage is specified
1459   for every row, corresponding to both DIAGONAL and OFF-DIAGONAL submatrices.
1460   In the above case the values for `d_nnz`, `o_nnz` are
1461 .vb
1462      proc0 - d_nnz = [2,2,2] and o_nnz = [2,2,2]
1463      proc1 - d_nnz = [3,3,2] and o_nnz = [2,1,1]
1464      proc2 - d_nnz = [1,1]   and o_nnz = [4,4]
1465 .ve
1466   Here the space allocated is still 37 though there are 34 nonzeros because
1467   the allocation is always done according to rlenmax.
1468 
1469   Level: intermediate
1470 
1471   Notes:
1472   It is recommended that one use the `MatCreate()`, `MatSetType()` and/or `MatSetFromOptions()`,
1473   MatXXXXSetPreallocation() paradigm instead of this routine directly.
1474   [MatXXXXSetPreallocation() is, for example, `MatSeqSELLSetPreallocation()`]
1475 
1476   If the *_rlen parameter is given then the *_rlenmax parameter is ignored
1477 
1478   `m`, `n`, `M`, `N` parameters specify the size of the matrix, and its partitioning across
1479   processors, while `d_rlenmax`, `d_rlen`, `o_rlenmax` , `o_rlen` parameters specify the approximate
1480   storage requirements for this matrix.
1481 
1482   If `PETSC_DECIDE` or  `PETSC_DETERMINE` is used for a particular argument on one
1483   processor than it must be used on all processors that share the object for
1484   that argument.
1485 
1486   The user MUST specify either the local or global matrix dimensions
1487   (possibly both).
1488 
1489   The parallel matrix is partitioned across processors such that the
1490   first m0 rows belong to process 0, the next m1 rows belong to
1491   process 1, the next m2 rows belong to process 2 etc.. where
1492   m0,m1,m2,.. are the input parameter 'm'. i.e each processor stores
1493   values corresponding to [`m` x `N`] submatrix.
1494 
1495   The columns are logically partitioned with the n0 columns belonging
1496   to 0th partition, the next n1 columns belonging to the next
1497   partition etc.. where n0,n1,n2... are the input parameter `n`.
1498 
1499   The DIAGONAL portion of the local submatrix on any given processor
1500   is the submatrix corresponding to the rows and columns `m`, `n`
1501   corresponding to the given processor. i.e diagonal matrix on
1502   process 0 is [m0 x n0], diagonal matrix on process 1 is [m1 x n1]
1503   etc. The remaining portion of the local submatrix [m x (N-n)]
1504   constitute the OFF-DIAGONAL portion. The example below better
1505   illustrates this concept.
1506 
1507   For a square global matrix we define each processor's diagonal portion
1508   to be its local rows and the corresponding columns (a square submatrix);
1509   each processor's off-diagonal portion encompasses the remainder of the
1510   local matrix (a rectangular submatrix).
1511 
1512   If `o_rlen`, `d_rlen` are specified, then `o_rlenmax`, and `d_rlenmax` are ignored.
1513 
1514   When calling this routine with a single process communicator, a matrix of
1515   type `MATSEQSELL` is returned.  If a matrix of type `MATMPISELL` is desired for this
1516   type of communicator, use the construction mechanism
1517 .vb
1518    MatCreate(...,&A);
1519    MatSetType(A,MATMPISELL);
1520    MatSetSizes(A, m,n,M,N);
1521    MatMPISELLSetPreallocation(A,...);
1522 .ve
1523 
1524 .seealso: `Mat`, `MATSELL`, `MatCreate()`, `MatCreateSeqSELL()`, `MatSetValues()`, `MatMPISELLSetPreallocation()`, `MATMPISELL`
1525 @*/
1526 PetscErrorCode MatCreateSELL(MPI_Comm comm, PetscInt m, PetscInt n, PetscInt M, PetscInt N, PetscInt d_rlenmax, const PetscInt d_rlen[], PetscInt o_rlenmax, const PetscInt o_rlen[], Mat *A)
1527 {
1528   PetscMPIInt size;
1529 
1530   PetscFunctionBegin;
1531   PetscCall(MatCreate(comm, A));
1532   PetscCall(MatSetSizes(*A, m, n, M, N));
1533   PetscCallMPI(MPI_Comm_size(comm, &size));
1534   if (size > 1) {
1535     PetscCall(MatSetType(*A, MATMPISELL));
1536     PetscCall(MatMPISELLSetPreallocation(*A, d_rlenmax, d_rlen, o_rlenmax, o_rlen));
1537   } else {
1538     PetscCall(MatSetType(*A, MATSEQSELL));
1539     PetscCall(MatSeqSELLSetPreallocation(*A, d_rlenmax, d_rlen));
1540   }
1541   PetscFunctionReturn(PETSC_SUCCESS);
1542 }
1543 
1544 /*@C
1545   MatMPISELLGetSeqSELL - Returns the local pieces of this distributed matrix
1546 
1547   Not Collective
1548 
1549   Input Parameter:
1550 . A - the `MATMPISELL` matrix
1551 
1552   Output Parameters:
1553 + Ad     - The diagonal portion of `A`
1554 . Ao     - The off-diagonal portion of `A`
1555 - colmap - An array mapping local column numbers of `Ao` to global column numbers of the parallel matrix
1556 
1557   Level: advanced
1558 
1559 .seealso: `Mat`, `MATSEQSELL`, `MATMPISELL`
1560 @*/
1561 PetscErrorCode MatMPISELLGetSeqSELL(Mat A, Mat *Ad, Mat *Ao, const PetscInt *colmap[])
1562 {
1563   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
1564   PetscBool    flg;
1565 
1566   PetscFunctionBegin;
1567   PetscCall(PetscObjectTypeCompare((PetscObject)A, MATMPISELL, &flg));
1568   PetscCheck(flg, PetscObjectComm((PetscObject)A), PETSC_ERR_SUP, "This function requires a MATMPISELL matrix as input");
1569   if (Ad) *Ad = a->A;
1570   if (Ao) *Ao = a->B;
1571   if (colmap) *colmap = a->garray;
1572   PetscFunctionReturn(PETSC_SUCCESS);
1573 }
1574 
1575 /*@C
1576   MatMPISELLGetLocalMatCondensed - Creates a `MATSEQSELL` matrix from an `MATMPISELL` matrix by
1577   taking all its local rows and NON-ZERO columns
1578 
1579   Not Collective
1580 
1581   Input Parameters:
1582 + A     - the matrix
1583 . scall - either `MAT_INITIAL_MATRIX` or `MAT_REUSE_MATRIX`
1584 . row   - index sets of rows to extract (or `NULL`)
1585 - col   - index sets of columns to extract (or `NULL`)
1586 
1587   Output Parameter:
1588 . A_loc - the local sequential matrix generated
1589 
1590   Level: advanced
1591 
1592 .seealso: `Mat`, `MATSEQSELL`, `MATMPISELL`, `MatGetOwnershipRange()`, `MatMPISELLGetLocalMat()`
1593 @*/
1594 PetscErrorCode MatMPISELLGetLocalMatCondensed(Mat A, MatReuse scall, IS *row, IS *col, Mat *A_loc)
1595 {
1596   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
1597   PetscInt     i, start, end, ncols, nzA, nzB, *cmap, imark, *idx;
1598   IS           isrowa, iscola;
1599   Mat         *aloc;
1600   PetscBool    match;
1601 
1602   PetscFunctionBegin;
1603   PetscCall(PetscObjectTypeCompare((PetscObject)A, MATMPISELL, &match));
1604   PetscCheck(match, PetscObjectComm((PetscObject)A), PETSC_ERR_SUP, "Requires MATMPISELL matrix as input");
1605   PetscCall(PetscLogEventBegin(MAT_Getlocalmatcondensed, A, 0, 0, 0));
1606   if (!row) {
1607     start = A->rmap->rstart;
1608     end   = A->rmap->rend;
1609     PetscCall(ISCreateStride(PETSC_COMM_SELF, end - start, start, 1, &isrowa));
1610   } else {
1611     isrowa = *row;
1612   }
1613   if (!col) {
1614     start = A->cmap->rstart;
1615     cmap  = a->garray;
1616     nzA   = a->A->cmap->n;
1617     nzB   = a->B->cmap->n;
1618     PetscCall(PetscMalloc1(nzA + nzB, &idx));
1619     ncols = 0;
1620     for (i = 0; i < nzB; i++) {
1621       if (cmap[i] < start) idx[ncols++] = cmap[i];
1622       else break;
1623     }
1624     imark = i;
1625     for (i = 0; i < nzA; i++) idx[ncols++] = start + i;
1626     for (i = imark; i < nzB; i++) idx[ncols++] = cmap[i];
1627     PetscCall(ISCreateGeneral(PETSC_COMM_SELF, ncols, idx, PETSC_OWN_POINTER, &iscola));
1628   } else {
1629     iscola = *col;
1630   }
1631   if (scall != MAT_INITIAL_MATRIX) {
1632     PetscCall(PetscMalloc1(1, &aloc));
1633     aloc[0] = *A_loc;
1634   }
1635   PetscCall(MatCreateSubMatrices(A, 1, &isrowa, &iscola, scall, &aloc));
1636   *A_loc = aloc[0];
1637   PetscCall(PetscFree(aloc));
1638   if (!row) PetscCall(ISDestroy(&isrowa));
1639   if (!col) PetscCall(ISDestroy(&iscola));
1640   PetscCall(PetscLogEventEnd(MAT_Getlocalmatcondensed, A, 0, 0, 0));
1641   PetscFunctionReturn(PETSC_SUCCESS);
1642 }
1643 
1644 #include <../src/mat/impls/aij/mpi/mpiaij.h>
1645 
1646 PetscErrorCode MatConvert_MPISELL_MPIAIJ(Mat A, MatType newtype, MatReuse reuse, Mat *newmat)
1647 {
1648   Mat_MPISELL *a = (Mat_MPISELL *)A->data;
1649   Mat          B;
1650   Mat_MPIAIJ  *b;
1651 
1652   PetscFunctionBegin;
1653   PetscCheck(A->assembled, PetscObjectComm((PetscObject)A), PETSC_ERR_SUP, "Matrix must be assembled");
1654 
1655   if (reuse == MAT_REUSE_MATRIX) {
1656     B = *newmat;
1657   } else {
1658     PetscCall(MatCreate(PetscObjectComm((PetscObject)A), &B));
1659     PetscCall(MatSetType(B, MATMPIAIJ));
1660     PetscCall(MatSetSizes(B, A->rmap->n, A->cmap->n, A->rmap->N, A->cmap->N));
1661     PetscCall(MatSetBlockSizes(B, A->rmap->bs, A->cmap->bs));
1662     PetscCall(MatSeqAIJSetPreallocation(B, 0, NULL));
1663     PetscCall(MatMPIAIJSetPreallocation(B, 0, NULL, 0, NULL));
1664   }
1665   b = (Mat_MPIAIJ *)B->data;
1666 
1667   if (reuse == MAT_REUSE_MATRIX) {
1668     PetscCall(MatConvert_SeqSELL_SeqAIJ(a->A, MATSEQAIJ, MAT_REUSE_MATRIX, &b->A));
1669     PetscCall(MatConvert_SeqSELL_SeqAIJ(a->B, MATSEQAIJ, MAT_REUSE_MATRIX, &b->B));
1670   } else {
1671     PetscCall(MatDestroy(&b->A));
1672     PetscCall(MatDestroy(&b->B));
1673     PetscCall(MatDisAssemble_MPISELL(A));
1674     PetscCall(MatConvert_SeqSELL_SeqAIJ(a->A, MATSEQAIJ, MAT_INITIAL_MATRIX, &b->A));
1675     PetscCall(MatConvert_SeqSELL_SeqAIJ(a->B, MATSEQAIJ, MAT_INITIAL_MATRIX, &b->B));
1676     PetscCall(MatAssemblyBegin(B, MAT_FINAL_ASSEMBLY));
1677     PetscCall(MatAssemblyEnd(B, MAT_FINAL_ASSEMBLY));
1678     PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
1679     PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
1680   }
1681 
1682   if (reuse == MAT_INPLACE_MATRIX) {
1683     PetscCall(MatHeaderReplace(A, &B));
1684   } else {
1685     *newmat = B;
1686   }
1687   PetscFunctionReturn(PETSC_SUCCESS);
1688 }
1689 
1690 PetscErrorCode MatConvert_MPIAIJ_MPISELL(Mat A, MatType newtype, MatReuse reuse, Mat *newmat)
1691 {
1692   Mat_MPIAIJ  *a = (Mat_MPIAIJ *)A->data;
1693   Mat          B;
1694   Mat_MPISELL *b;
1695 
1696   PetscFunctionBegin;
1697   PetscCheck(A->assembled, PetscObjectComm((PetscObject)A), PETSC_ERR_SUP, "Matrix must be assembled");
1698 
1699   if (reuse == MAT_REUSE_MATRIX) {
1700     B = *newmat;
1701   } else {
1702     Mat_SeqAIJ *Aa = (Mat_SeqAIJ *)a->A->data, *Ba = (Mat_SeqAIJ *)a->B->data;
1703     PetscInt    i, d_nz = 0, o_nz = 0, m = A->rmap->N, n = A->cmap->N, lm = A->rmap->n, ln = A->cmap->n;
1704     PetscInt   *d_nnz, *o_nnz;
1705     PetscCall(PetscMalloc2(lm, &d_nnz, lm, &o_nnz));
1706     for (i = 0; i < lm; i++) {
1707       d_nnz[i] = Aa->i[i + 1] - Aa->i[i];
1708       o_nnz[i] = Ba->i[i + 1] - Ba->i[i];
1709       if (d_nnz[i] > d_nz) d_nz = d_nnz[i];
1710       if (o_nnz[i] > o_nz) o_nz = o_nnz[i];
1711     }
1712     PetscCall(MatCreate(PetscObjectComm((PetscObject)A), &B));
1713     PetscCall(MatSetType(B, MATMPISELL));
1714     PetscCall(MatSetSizes(B, lm, ln, m, n));
1715     PetscCall(MatSetBlockSizes(B, A->rmap->bs, A->cmap->bs));
1716     PetscCall(MatSeqSELLSetPreallocation(B, d_nz, d_nnz));
1717     PetscCall(MatMPISELLSetPreallocation(B, d_nz, d_nnz, o_nz, o_nnz));
1718     PetscCall(PetscFree2(d_nnz, o_nnz));
1719   }
1720   b = (Mat_MPISELL *)B->data;
1721 
1722   if (reuse == MAT_REUSE_MATRIX) {
1723     PetscCall(MatConvert_SeqAIJ_SeqSELL(a->A, MATSEQSELL, MAT_REUSE_MATRIX, &b->A));
1724     PetscCall(MatConvert_SeqAIJ_SeqSELL(a->B, MATSEQSELL, MAT_REUSE_MATRIX, &b->B));
1725   } else {
1726     PetscCall(MatDestroy(&b->A));
1727     PetscCall(MatDestroy(&b->B));
1728     PetscCall(MatConvert_SeqAIJ_SeqSELL(a->A, MATSEQSELL, MAT_INITIAL_MATRIX, &b->A));
1729     PetscCall(MatConvert_SeqAIJ_SeqSELL(a->B, MATSEQSELL, MAT_INITIAL_MATRIX, &b->B));
1730     PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
1731     PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
1732     PetscCall(MatAssemblyBegin(B, MAT_FINAL_ASSEMBLY));
1733     PetscCall(MatAssemblyEnd(B, MAT_FINAL_ASSEMBLY));
1734   }
1735 
1736   if (reuse == MAT_INPLACE_MATRIX) {
1737     PetscCall(MatHeaderReplace(A, &B));
1738   } else {
1739     *newmat = B;
1740   }
1741   PetscFunctionReturn(PETSC_SUCCESS);
1742 }
1743 
1744 PetscErrorCode MatSOR_MPISELL(Mat matin, Vec bb, PetscReal omega, MatSORType flag, PetscReal fshift, PetscInt its, PetscInt lits, Vec xx)
1745 {
1746   Mat_MPISELL *mat = (Mat_MPISELL *)matin->data;
1747   Vec          bb1 = NULL;
1748 
1749   PetscFunctionBegin;
1750   if (flag == SOR_APPLY_UPPER) {
1751     PetscCall((*mat->A->ops->sor)(mat->A, bb, omega, flag, fshift, lits, 1, xx));
1752     PetscFunctionReturn(PETSC_SUCCESS);
1753   }
1754 
1755   if (its > 1 || ~flag & SOR_ZERO_INITIAL_GUESS || flag & SOR_EISENSTAT) PetscCall(VecDuplicate(bb, &bb1));
1756 
1757   if ((flag & SOR_LOCAL_SYMMETRIC_SWEEP) == SOR_LOCAL_SYMMETRIC_SWEEP) {
1758     if (flag & SOR_ZERO_INITIAL_GUESS) {
1759       PetscCall((*mat->A->ops->sor)(mat->A, bb, omega, flag, fshift, lits, 1, xx));
1760       its--;
1761     }
1762 
1763     while (its--) {
1764       PetscCall(VecScatterBegin(mat->Mvctx, xx, mat->lvec, INSERT_VALUES, SCATTER_FORWARD));
1765       PetscCall(VecScatterEnd(mat->Mvctx, xx, mat->lvec, INSERT_VALUES, SCATTER_FORWARD));
1766 
1767       /* update rhs: bb1 = bb - B*x */
1768       PetscCall(VecScale(mat->lvec, -1.0));
1769       PetscCall((*mat->B->ops->multadd)(mat->B, mat->lvec, bb, bb1));
1770 
1771       /* local sweep */
1772       PetscCall((*mat->A->ops->sor)(mat->A, bb1, omega, SOR_SYMMETRIC_SWEEP, fshift, lits, 1, xx));
1773     }
1774   } else if (flag & SOR_LOCAL_FORWARD_SWEEP) {
1775     if (flag & SOR_ZERO_INITIAL_GUESS) {
1776       PetscCall((*mat->A->ops->sor)(mat->A, bb, omega, flag, fshift, lits, 1, xx));
1777       its--;
1778     }
1779     while (its--) {
1780       PetscCall(VecScatterBegin(mat->Mvctx, xx, mat->lvec, INSERT_VALUES, SCATTER_FORWARD));
1781       PetscCall(VecScatterEnd(mat->Mvctx, xx, mat->lvec, INSERT_VALUES, SCATTER_FORWARD));
1782 
1783       /* update rhs: bb1 = bb - B*x */
1784       PetscCall(VecScale(mat->lvec, -1.0));
1785       PetscCall((*mat->B->ops->multadd)(mat->B, mat->lvec, bb, bb1));
1786 
1787       /* local sweep */
1788       PetscCall((*mat->A->ops->sor)(mat->A, bb1, omega, SOR_FORWARD_SWEEP, fshift, lits, 1, xx));
1789     }
1790   } else if (flag & SOR_LOCAL_BACKWARD_SWEEP) {
1791     if (flag & SOR_ZERO_INITIAL_GUESS) {
1792       PetscCall((*mat->A->ops->sor)(mat->A, bb, omega, flag, fshift, lits, 1, xx));
1793       its--;
1794     }
1795     while (its--) {
1796       PetscCall(VecScatterBegin(mat->Mvctx, xx, mat->lvec, INSERT_VALUES, SCATTER_FORWARD));
1797       PetscCall(VecScatterEnd(mat->Mvctx, xx, mat->lvec, INSERT_VALUES, SCATTER_FORWARD));
1798 
1799       /* update rhs: bb1 = bb - B*x */
1800       PetscCall(VecScale(mat->lvec, -1.0));
1801       PetscCall((*mat->B->ops->multadd)(mat->B, mat->lvec, bb, bb1));
1802 
1803       /* local sweep */
1804       PetscCall((*mat->A->ops->sor)(mat->A, bb1, omega, SOR_BACKWARD_SWEEP, fshift, lits, 1, xx));
1805     }
1806   } else SETERRQ(PetscObjectComm((PetscObject)matin), PETSC_ERR_SUP, "Parallel SOR not supported");
1807 
1808   PetscCall(VecDestroy(&bb1));
1809 
1810   matin->factorerrortype = mat->A->factorerrortype;
1811   PetscFunctionReturn(PETSC_SUCCESS);
1812 }
1813 
1814 #if defined(PETSC_HAVE_CUDA)
1815 PETSC_INTERN PetscErrorCode MatConvert_MPISELL_MPISELLCUDA(Mat, MatType, MatReuse, Mat *);
1816 #endif
1817 
1818 /*MC
1819    MATMPISELL - MATMPISELL = "MPISELL" - A matrix type to be used for parallel sparse matrices.
1820 
1821    Options Database Keys:
1822 . -mat_type mpisell - sets the matrix type to `MATMPISELL` during a call to `MatSetFromOptions()`
1823 
1824   Level: beginner
1825 
1826 .seealso: `Mat`, `MATSELL`, `MATSEQSELL` `MatCreateSELL()`
1827 M*/
1828 PETSC_EXTERN PetscErrorCode MatCreate_MPISELL(Mat B)
1829 {
1830   Mat_MPISELL *b;
1831   PetscMPIInt  size;
1832 
1833   PetscFunctionBegin;
1834   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)B), &size));
1835   PetscCall(PetscNew(&b));
1836   B->data       = (void *)b;
1837   B->ops[0]     = MatOps_Values;
1838   B->assembled  = PETSC_FALSE;
1839   B->insertmode = NOT_SET_VALUES;
1840   b->size       = size;
1841   PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)B), &b->rank));
1842   /* build cache for off array entries formed */
1843   PetscCall(MatStashCreate_Private(PetscObjectComm((PetscObject)B), 1, &B->stash));
1844 
1845   b->donotstash  = PETSC_FALSE;
1846   b->colmap      = NULL;
1847   b->garray      = NULL;
1848   b->roworiented = PETSC_TRUE;
1849 
1850   /* stuff used for matrix vector multiply */
1851   b->lvec  = NULL;
1852   b->Mvctx = NULL;
1853 
1854   /* stuff for MatGetRow() */
1855   b->rowindices   = NULL;
1856   b->rowvalues    = NULL;
1857   b->getrowactive = PETSC_FALSE;
1858 
1859   PetscCall(PetscObjectComposeFunction((PetscObject)B, "MatStoreValues_C", MatStoreValues_MPISELL));
1860   PetscCall(PetscObjectComposeFunction((PetscObject)B, "MatRetrieveValues_C", MatRetrieveValues_MPISELL));
1861   PetscCall(PetscObjectComposeFunction((PetscObject)B, "MatIsTranspose_C", MatIsTranspose_MPISELL));
1862   PetscCall(PetscObjectComposeFunction((PetscObject)B, "MatMPISELLSetPreallocation_C", MatMPISELLSetPreallocation_MPISELL));
1863   PetscCall(PetscObjectComposeFunction((PetscObject)B, "MatConvert_mpisell_mpiaij_C", MatConvert_MPISELL_MPIAIJ));
1864 #if defined(PETSC_HAVE_CUDA)
1865   PetscCall(PetscObjectComposeFunction((PetscObject)B, "MatConvert_mpisell_mpisellcuda_C", MatConvert_MPISELL_MPISELLCUDA));
1866 #endif
1867   PetscCall(PetscObjectComposeFunction((PetscObject)B, "MatDiagonalScaleLocal_C", MatDiagonalScaleLocal_MPISELL));
1868   PetscCall(PetscObjectChangeTypeName((PetscObject)B, MATMPISELL));
1869   PetscFunctionReturn(PETSC_SUCCESS);
1870 }
1871