Actual source code: matnest.c

  1: #include <../src/mat/impls/nest/matnestimpl.h>
  2: #include <../src/mat/impls/aij/seq/aij.h>
  3: #include <../src/mat/impls/shell/shell.h>
  4: #include <petscsf.h>

  6: static PetscErrorCode MatSetUp_NestIS_Private(Mat, PetscInt, const IS[], PetscInt, const IS[]);
  7: static PetscErrorCode MatCreateVecs_Nest(Mat, Vec *, Vec *);
  8: static PetscErrorCode MatReset_Nest(Mat);

 10: PETSC_INTERN PetscErrorCode MatConvert_Nest_IS(Mat, MatType, MatReuse, Mat *);

 12: /* private functions */
 13: static PetscErrorCode MatNestGetSizes_Private(Mat A, PetscInt *m, PetscInt *n, PetscInt *M, PetscInt *N)
 14: {
 15:   Mat_Nest *bA = (Mat_Nest *)A->data;
 16:   PetscInt  i, j;

 18:   PetscFunctionBegin;
 19:   *m = *n = *M = *N = 0;
 20:   for (i = 0; i < bA->nr; i++) { /* rows */
 21:     PetscInt sm, sM;
 22:     PetscCall(ISGetLocalSize(bA->isglobal.row[i], &sm));
 23:     PetscCall(ISGetSize(bA->isglobal.row[i], &sM));
 24:     *m += sm;
 25:     *M += sM;
 26:   }
 27:   for (j = 0; j < bA->nc; j++) { /* cols */
 28:     PetscInt sn, sN;
 29:     PetscCall(ISGetLocalSize(bA->isglobal.col[j], &sn));
 30:     PetscCall(ISGetSize(bA->isglobal.col[j], &sN));
 31:     *n += sn;
 32:     *N += sN;
 33:   }
 34:   PetscFunctionReturn(PETSC_SUCCESS);
 35: }

 37: /* operations */
 38: static PetscErrorCode MatMult_Nest(Mat A, Vec x, Vec y)
 39: {
 40:   Mat_Nest *bA = (Mat_Nest *)A->data;
 41:   Vec      *bx = bA->right, *by = bA->left;
 42:   PetscInt  i, j, nr = bA->nr, nc = bA->nc;

 44:   PetscFunctionBegin;
 45:   for (i = 0; i < nr; i++) PetscCall(VecGetSubVector(y, bA->isglobal.row[i], &by[i]));
 46:   for (i = 0; i < nc; i++) PetscCall(VecGetSubVector(x, bA->isglobal.col[i], &bx[i]));
 47:   for (i = 0; i < nr; i++) {
 48:     PetscCall(VecZeroEntries(by[i]));
 49:     for (j = 0; j < nc; j++) {
 50:       if (!bA->m[i][j]) continue;
 51:       /* y[i] <- y[i] + A[i][j] * x[j] */
 52:       PetscCall(MatMultAdd(bA->m[i][j], bx[j], by[i], by[i]));
 53:     }
 54:   }
 55:   for (i = 0; i < nr; i++) PetscCall(VecRestoreSubVector(y, bA->isglobal.row[i], &by[i]));
 56:   for (i = 0; i < nc; i++) PetscCall(VecRestoreSubVector(x, bA->isglobal.col[i], &bx[i]));
 57:   PetscFunctionReturn(PETSC_SUCCESS);
 58: }

 60: static PetscErrorCode MatMultAdd_Nest(Mat A, Vec x, Vec y, Vec z)
 61: {
 62:   Mat_Nest *bA = (Mat_Nest *)A->data;
 63:   Vec      *bx = bA->right, *bz = bA->left;
 64:   PetscInt  i, j, nr = bA->nr, nc = bA->nc;

 66:   PetscFunctionBegin;
 67:   for (i = 0; i < nr; i++) PetscCall(VecGetSubVector(z, bA->isglobal.row[i], &bz[i]));
 68:   for (i = 0; i < nc; i++) PetscCall(VecGetSubVector(x, bA->isglobal.col[i], &bx[i]));
 69:   for (i = 0; i < nr; i++) {
 70:     if (y != z) {
 71:       Vec by;
 72:       PetscCall(VecGetSubVector(y, bA->isglobal.row[i], &by));
 73:       PetscCall(VecCopy(by, bz[i]));
 74:       PetscCall(VecRestoreSubVector(y, bA->isglobal.row[i], &by));
 75:     }
 76:     for (j = 0; j < nc; j++) {
 77:       if (!bA->m[i][j]) continue;
 78:       /* y[i] <- y[i] + A[i][j] * x[j] */
 79:       PetscCall(MatMultAdd(bA->m[i][j], bx[j], bz[i], bz[i]));
 80:     }
 81:   }
 82:   for (i = 0; i < nr; i++) PetscCall(VecRestoreSubVector(z, bA->isglobal.row[i], &bz[i]));
 83:   for (i = 0; i < nc; i++) PetscCall(VecRestoreSubVector(x, bA->isglobal.col[i], &bx[i]));
 84:   PetscFunctionReturn(PETSC_SUCCESS);
 85: }

 87: typedef struct {
 88:   Mat         *workC;      /* array of Mat with specific containers depending on the underlying MatMatMult implementation */
 89:   PetscScalar *tarray;     /* buffer for storing all temporary products A[i][j] B[j] */
 90:   PetscInt    *dm, *dn, k; /* displacements and number of submatrices */
 91: } Nest_Dense;

 93: static PetscErrorCode MatProductNumeric_Nest_Dense(Mat C)
 94: {
 95:   Mat_Nest          *bA;
 96:   Nest_Dense        *contents;
 97:   Mat                viewB, viewC, productB, workC;
 98:   const PetscScalar *barray;
 99:   PetscScalar       *carray;
100:   PetscInt           i, j, M, N, nr, nc, ldb, ldc;
101:   Mat                A, B;

103:   PetscFunctionBegin;
104:   MatCheckProduct(C, 1);
105:   A = C->product->A;
106:   B = C->product->B;
107:   PetscCall(MatGetSize(B, NULL, &N));
108:   if (!N) {
109:     PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
110:     PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
111:     PetscFunctionReturn(PETSC_SUCCESS);
112:   }
113:   contents = (Nest_Dense *)C->product->data;
114:   PetscCheck(contents, PetscObjectComm((PetscObject)C), PETSC_ERR_PLIB, "Product data empty");
115:   bA = (Mat_Nest *)A->data;
116:   nr = bA->nr;
117:   nc = bA->nc;
118:   PetscCall(MatDenseGetLDA(B, &ldb));
119:   PetscCall(MatDenseGetLDA(C, &ldc));
120:   PetscCall(MatZeroEntries(C));
121:   PetscCall(MatDenseGetArrayRead(B, &barray));
122:   PetscCall(MatDenseGetArray(C, &carray));
123:   for (i = 0; i < nr; i++) {
124:     PetscCall(ISGetSize(bA->isglobal.row[i], &M));
125:     PetscCall(MatCreateDense(PetscObjectComm((PetscObject)A), contents->dm[i + 1] - contents->dm[i], PETSC_DECIDE, M, N, PetscSafePointerPlusOffset(carray, contents->dm[i]), &viewC));
126:     PetscCall(MatDenseSetLDA(viewC, ldc));
127:     for (j = 0; j < nc; j++) {
128:       if (!bA->m[i][j]) continue;
129:       PetscCall(ISGetSize(bA->isglobal.col[j], &M));
130:       PetscCall(MatCreateDense(PetscObjectComm((PetscObject)A), contents->dn[j + 1] - contents->dn[j], PETSC_DECIDE, M, N, PetscSafePointerPlusOffset((PetscScalar *)barray, contents->dn[j]), &viewB));
131:       PetscCall(MatDenseSetLDA(viewB, ldb));

133:       /* MatMatMultNumeric(bA->m[i][j],viewB,contents->workC[i*nc + j]); */
134:       workC             = contents->workC[i * nc + j];
135:       productB          = workC->product->B;
136:       workC->product->B = viewB; /* use newly created dense matrix viewB */
137:       PetscCall(MatProductNumeric(workC));
138:       PetscCall(MatDestroy(&viewB));
139:       workC->product->B = productB; /* resume original B */

141:       /* C[i] <- workC + C[i] */
142:       PetscCall(MatAXPY(viewC, 1.0, contents->workC[i * nc + j], SAME_NONZERO_PATTERN));
143:     }
144:     PetscCall(MatDestroy(&viewC));
145:   }
146:   PetscCall(MatDenseRestoreArray(C, &carray));
147:   PetscCall(MatDenseRestoreArrayRead(B, &barray));

149:   PetscCall(MatSetOption(C, MAT_NO_OFF_PROC_ENTRIES, PETSC_TRUE));
150:   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
151:   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
152:   PetscFunctionReturn(PETSC_SUCCESS);
153: }

155: static PetscErrorCode MatNest_DenseDestroy(void *ctx)
156: {
157:   Nest_Dense *contents = (Nest_Dense *)ctx;
158:   PetscInt    i;

160:   PetscFunctionBegin;
161:   PetscCall(PetscFree(contents->tarray));
162:   for (i = 0; i < contents->k; i++) PetscCall(MatDestroy(contents->workC + i));
163:   PetscCall(PetscFree3(contents->dm, contents->dn, contents->workC));
164:   PetscCall(PetscFree(contents));
165:   PetscFunctionReturn(PETSC_SUCCESS);
166: }

168: static PetscErrorCode MatProductSymbolic_Nest_Dense(Mat C)
169: {
170:   Mat_Nest          *bA;
171:   Mat                viewB, workC;
172:   const PetscScalar *barray;
173:   PetscInt           i, j, M, N, m, n, nr, nc, maxm = 0, ldb;
174:   Nest_Dense        *contents = NULL;
175:   PetscBool          cisdense;
176:   Mat                A, B;
177:   PetscReal          fill;

179:   PetscFunctionBegin;
180:   MatCheckProduct(C, 1);
181:   PetscCheck(!C->product->data, PetscObjectComm((PetscObject)C), PETSC_ERR_PLIB, "Product data not empty");
182:   A    = C->product->A;
183:   B    = C->product->B;
184:   fill = C->product->fill;
185:   bA   = (Mat_Nest *)A->data;
186:   nr   = bA->nr;
187:   nc   = bA->nc;
188:   PetscCall(MatGetLocalSize(C, &m, &n));
189:   PetscCall(MatGetSize(C, &M, &N));
190:   if (m == PETSC_DECIDE || n == PETSC_DECIDE || M == PETSC_DECIDE || N == PETSC_DECIDE) {
191:     PetscCall(MatGetLocalSize(B, NULL, &n));
192:     PetscCall(MatGetSize(B, NULL, &N));
193:     PetscCall(MatGetLocalSize(A, &m, NULL));
194:     PetscCall(MatGetSize(A, &M, NULL));
195:     PetscCall(MatSetSizes(C, m, n, M, N));
196:   }
197:   PetscCall(PetscObjectTypeCompareAny((PetscObject)C, &cisdense, MATSEQDENSE, MATMPIDENSE, MATSEQDENSECUDA, MATMPIDENSECUDA, ""));
198:   if (!cisdense) PetscCall(MatSetType(C, ((PetscObject)B)->type_name));
199:   PetscCall(MatSetUp(C));
200:   if (!N) {
201:     C->ops->productnumeric = MatProductNumeric_Nest_Dense;
202:     PetscFunctionReturn(PETSC_SUCCESS);
203:   }

205:   PetscCall(PetscNew(&contents));
206:   C->product->data    = contents;
207:   C->product->destroy = MatNest_DenseDestroy;
208:   PetscCall(PetscCalloc3(nr + 1, &contents->dm, nc + 1, &contents->dn, nr * nc, &contents->workC));
209:   contents->k = nr * nc;
210:   for (i = 0; i < nr; i++) {
211:     PetscCall(ISGetLocalSize(bA->isglobal.row[i], contents->dm + i + 1));
212:     maxm = PetscMax(maxm, contents->dm[i + 1]);
213:     contents->dm[i + 1] += contents->dm[i];
214:   }
215:   for (i = 0; i < nc; i++) {
216:     PetscCall(ISGetLocalSize(bA->isglobal.col[i], contents->dn + i + 1));
217:     contents->dn[i + 1] += contents->dn[i];
218:   }
219:   PetscCall(PetscMalloc1(maxm * N, &contents->tarray));
220:   PetscCall(MatDenseGetLDA(B, &ldb));
221:   PetscCall(MatGetSize(B, NULL, &N));
222:   PetscCall(MatDenseGetArrayRead(B, &barray));
223:   /* loops are permuted compared to MatMatMultNumeric so that viewB is created only once per column of A */
224:   for (j = 0; j < nc; j++) {
225:     PetscCall(ISGetSize(bA->isglobal.col[j], &M));
226:     PetscCall(MatCreateDense(PetscObjectComm((PetscObject)A), contents->dn[j + 1] - contents->dn[j], PETSC_DECIDE, M, N, PetscSafePointerPlusOffset((PetscScalar *)barray, contents->dn[j]), &viewB));
227:     PetscCall(MatDenseSetLDA(viewB, ldb));
228:     for (i = 0; i < nr; i++) {
229:       if (!bA->m[i][j]) continue;
230:       /* MatMatMultSymbolic may attach a specific container (depending on MatType of bA->m[i][j]) to workC[i][j] */

232:       PetscCall(MatProductCreate(bA->m[i][j], viewB, NULL, &contents->workC[i * nc + j]));
233:       workC = contents->workC[i * nc + j];
234:       PetscCall(MatProductSetType(workC, MATPRODUCT_AB));
235:       PetscCall(MatProductSetAlgorithm(workC, "default"));
236:       PetscCall(MatProductSetFill(workC, fill));
237:       PetscCall(MatProductSetFromOptions(workC));
238:       PetscCall(MatProductSymbolic(workC));

240:       /* since tarray will be shared by all Mat */
241:       PetscCall(MatSeqDenseSetPreallocation(workC, contents->tarray));
242:       PetscCall(MatMPIDenseSetPreallocation(workC, contents->tarray));
243:     }
244:     PetscCall(MatDestroy(&viewB));
245:   }
246:   PetscCall(MatDenseRestoreArrayRead(B, &barray));

248:   C->ops->productnumeric = MatProductNumeric_Nest_Dense;
249:   PetscFunctionReturn(PETSC_SUCCESS);
250: }

252: static PetscErrorCode MatProductSetFromOptions_Nest_Dense(Mat C)
253: {
254:   Mat_Product *product = C->product;

256:   PetscFunctionBegin;
257:   if (product->type == MATPRODUCT_AB) C->ops->productsymbolic = MatProductSymbolic_Nest_Dense;
258:   PetscFunctionReturn(PETSC_SUCCESS);
259: }

261: static PetscErrorCode MatMultTransposeKernel_Nest(Mat A, Vec x, Vec y, PetscBool herm)
262: {
263:   Mat_Nest *bA = (Mat_Nest *)A->data;
264:   Vec      *bx = bA->left, *by = bA->right;
265:   PetscInt  i, j, nr = bA->nr, nc = bA->nc;

267:   PetscFunctionBegin;
268:   for (i = 0; i < nr; i++) PetscCall(VecGetSubVector(x, bA->isglobal.row[i], &bx[i]));
269:   for (i = 0; i < nc; i++) PetscCall(VecGetSubVector(y, bA->isglobal.col[i], &by[i]));
270:   for (j = 0; j < nc; j++) {
271:     PetscCall(VecZeroEntries(by[j]));
272:     for (i = 0; i < nr; i++) {
273:       if (!bA->m[i][j]) continue;
274:       if (herm) PetscCall(MatMultHermitianTransposeAdd(bA->m[i][j], bx[i], by[j], by[j])); /* y[j] <- y[j] + (A[i][j])^H * x[i] */
275:       else PetscCall(MatMultTransposeAdd(bA->m[i][j], bx[i], by[j], by[j]));               /* y[j] <- y[j] + (A[i][j])^T * x[i] */
276:     }
277:   }
278:   for (i = 0; i < nr; i++) PetscCall(VecRestoreSubVector(x, bA->isglobal.row[i], &bx[i]));
279:   for (i = 0; i < nc; i++) PetscCall(VecRestoreSubVector(y, bA->isglobal.col[i], &by[i]));
280:   PetscFunctionReturn(PETSC_SUCCESS);
281: }

283: static PetscErrorCode MatMultTranspose_Nest(Mat A, Vec x, Vec y)
284: {
285:   PetscFunctionBegin;
286:   PetscCall(MatMultTransposeKernel_Nest(A, x, y, PETSC_FALSE));
287:   PetscFunctionReturn(PETSC_SUCCESS);
288: }

290: static PetscErrorCode MatMultHermitianTranspose_Nest(Mat A, Vec x, Vec y)
291: {
292:   PetscFunctionBegin;
293:   PetscCall(MatMultTransposeKernel_Nest(A, x, y, PETSC_TRUE));
294:   PetscFunctionReturn(PETSC_SUCCESS);
295: }

297: static PetscErrorCode MatMultTransposeAddKernel_Nest(Mat A, Vec x, Vec y, Vec z, PetscBool herm)
298: {
299:   Mat_Nest *bA = (Mat_Nest *)A->data;
300:   Vec      *bx = bA->left, *bz = bA->right;
301:   PetscInt  i, j, nr = bA->nr, nc = bA->nc;

303:   PetscFunctionBegin;
304:   for (i = 0; i < nr; i++) PetscCall(VecGetSubVector(x, bA->isglobal.row[i], &bx[i]));
305:   for (i = 0; i < nc; i++) PetscCall(VecGetSubVector(z, bA->isglobal.col[i], &bz[i]));
306:   for (j = 0; j < nc; j++) {
307:     if (y != z) {
308:       Vec by;
309:       PetscCall(VecGetSubVector(y, bA->isglobal.col[j], &by));
310:       PetscCall(VecCopy(by, bz[j]));
311:       PetscCall(VecRestoreSubVector(y, bA->isglobal.col[j], &by));
312:     }
313:     for (i = 0; i < nr; i++) {
314:       if (!bA->m[i][j]) continue;
315:       if (herm) PetscCall(MatMultHermitianTransposeAdd(bA->m[i][j], bx[i], bz[j], bz[j])); /* z[j] <- y[j] + (A[i][j])^H * x[i] */
316:       else PetscCall(MatMultTransposeAdd(bA->m[i][j], bx[i], bz[j], bz[j]));               /* z[j] <- y[j] + (A[i][j])^T * x[i] */
317:     }
318:   }
319:   for (i = 0; i < nr; i++) PetscCall(VecRestoreSubVector(x, bA->isglobal.row[i], &bx[i]));
320:   for (i = 0; i < nc; i++) PetscCall(VecRestoreSubVector(z, bA->isglobal.col[i], &bz[i]));
321:   PetscFunctionReturn(PETSC_SUCCESS);
322: }

324: static PetscErrorCode MatMultTransposeAdd_Nest(Mat A, Vec x, Vec y, Vec z)
325: {
326:   PetscFunctionBegin;
327:   PetscCall(MatMultTransposeAddKernel_Nest(A, x, y, z, PETSC_FALSE));
328:   PetscFunctionReturn(PETSC_SUCCESS);
329: }

331: static PetscErrorCode MatMultHermitianTransposeAdd_Nest(Mat A, Vec x, Vec y, Vec z)
332: {
333:   PetscFunctionBegin;
334:   PetscCall(MatMultTransposeAddKernel_Nest(A, x, y, z, PETSC_TRUE));
335:   PetscFunctionReturn(PETSC_SUCCESS);
336: }

338: static PetscErrorCode MatTranspose_Nest(Mat A, MatReuse reuse, Mat *B)
339: {
340:   Mat_Nest *bA = (Mat_Nest *)A->data, *bC;
341:   Mat       C;
342:   PetscInt  i, j, nr = bA->nr, nc = bA->nc;

344:   PetscFunctionBegin;
345:   if (reuse == MAT_REUSE_MATRIX) PetscCall(MatTransposeCheckNonzeroState_Private(A, *B));
346:   PetscCheck(reuse != MAT_INPLACE_MATRIX || nr == nc, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_SIZ, "Square nested matrix only for in-place");

348:   if (reuse == MAT_INITIAL_MATRIX || reuse == MAT_INPLACE_MATRIX) {
349:     Mat *subs;
350:     IS  *is_row, *is_col;

352:     PetscCall(PetscCalloc1(nr * nc, &subs));
353:     PetscCall(PetscMalloc2(nr, &is_row, nc, &is_col));
354:     PetscCall(MatNestGetISs(A, is_row, is_col));
355:     if (reuse == MAT_INPLACE_MATRIX) {
356:       for (i = 0; i < nr; i++) {
357:         for (j = 0; j < nc; j++) subs[i + nr * j] = bA->m[i][j];
358:       }
359:     }

361:     PetscCall(MatCreateNest(PetscObjectComm((PetscObject)A), nc, is_col, nr, is_row, subs, &C));
362:     PetscCall(PetscFree(subs));
363:     PetscCall(PetscFree2(is_row, is_col));
364:   } else {
365:     C = *B;
366:   }

368:   bC = (Mat_Nest *)C->data;
369:   for (i = 0; i < nr; i++) {
370:     for (j = 0; j < nc; j++) {
371:       if (bA->m[i][j]) {
372:         PetscCall(MatTranspose(bA->m[i][j], reuse, &bC->m[j][i]));
373:       } else {
374:         bC->m[j][i] = NULL;
375:       }
376:     }
377:   }

379:   if (reuse == MAT_INITIAL_MATRIX || reuse == MAT_REUSE_MATRIX) {
380:     *B = C;
381:   } else {
382:     PetscCall(MatHeaderMerge(A, &C));
383:   }
384:   PetscFunctionReturn(PETSC_SUCCESS);
385: }

387: static PetscErrorCode MatNestDestroyISList(PetscInt n, IS **list)
388: {
389:   IS      *lst = *list;
390:   PetscInt i;

392:   PetscFunctionBegin;
393:   if (!lst) PetscFunctionReturn(PETSC_SUCCESS);
394:   for (i = 0; i < n; i++)
395:     if (lst[i]) PetscCall(ISDestroy(&lst[i]));
396:   PetscCall(PetscFree(lst));
397:   *list = NULL;
398:   PetscFunctionReturn(PETSC_SUCCESS);
399: }

401: static PetscErrorCode MatReset_Nest(Mat A)
402: {
403:   Mat_Nest *vs = (Mat_Nest *)A->data;
404:   PetscInt  i, j;

406:   PetscFunctionBegin;
407:   /* release the matrices and the place holders */
408:   PetscCall(MatNestDestroyISList(vs->nr, &vs->isglobal.row));
409:   PetscCall(MatNestDestroyISList(vs->nc, &vs->isglobal.col));
410:   PetscCall(MatNestDestroyISList(vs->nr, &vs->islocal.row));
411:   PetscCall(MatNestDestroyISList(vs->nc, &vs->islocal.col));

413:   PetscCall(PetscFree(vs->row_len));
414:   PetscCall(PetscFree(vs->col_len));
415:   PetscCall(PetscFree(vs->nnzstate));

417:   PetscCall(PetscFree2(vs->left, vs->right));

419:   /* release the matrices and the place holders */
420:   if (vs->m) {
421:     for (i = 0; i < vs->nr; i++) {
422:       for (j = 0; j < vs->nc; j++) PetscCall(MatDestroy(&vs->m[i][j]));
423:     }
424:     PetscCall(PetscFree(vs->m[0]));
425:     PetscCall(PetscFree(vs->m));
426:   }

428:   /* restore defaults */
429:   vs->nr            = 0;
430:   vs->nc            = 0;
431:   vs->splitassembly = PETSC_FALSE;
432:   PetscFunctionReturn(PETSC_SUCCESS);
433: }

435: static PetscErrorCode MatDestroy_Nest(Mat A)
436: {
437:   PetscFunctionBegin;
438:   PetscCall(MatReset_Nest(A));
439:   PetscCall(PetscFree(A->data));
440:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestGetSubMat_C", NULL));
441:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestSetSubMat_C", NULL));
442:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestGetSubMats_C", NULL));
443:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestGetSize_C", NULL));
444:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestGetISs_C", NULL));
445:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestGetLocalISs_C", NULL));
446:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestSetVecType_C", NULL));
447:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestSetSubMats_C", NULL));
448:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_mpiaij_C", NULL));
449:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_seqaij_C", NULL));
450:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_aij_C", NULL));
451:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_is_C", NULL));
452:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_mpidense_C", NULL));
453:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_seqdense_C", NULL));
454:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatProductSetFromOptions_nest_seqdense_C", NULL));
455:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatProductSetFromOptions_nest_mpidense_C", NULL));
456:   PetscFunctionReturn(PETSC_SUCCESS);
457: }

459: static PetscErrorCode MatMissingDiagonal_Nest(Mat mat, PetscBool *missing, PetscInt *dd)
460: {
461:   Mat_Nest *vs = (Mat_Nest *)mat->data;
462:   PetscInt  i;

464:   PetscFunctionBegin;
465:   if (dd) *dd = 0;
466:   if (!vs->nr) {
467:     *missing = PETSC_TRUE;
468:     PetscFunctionReturn(PETSC_SUCCESS);
469:   }
470:   *missing = PETSC_FALSE;
471:   for (i = 0; i < vs->nr && !*missing; i++) {
472:     *missing = PETSC_TRUE;
473:     if (vs->m[i][i]) {
474:       PetscCall(MatMissingDiagonal(vs->m[i][i], missing, NULL));
475:       PetscCheck(!*missing || !dd, PetscObjectComm((PetscObject)mat), PETSC_ERR_SUP, "First missing entry not yet implemented");
476:     }
477:   }
478:   PetscFunctionReturn(PETSC_SUCCESS);
479: }

481: static PetscErrorCode MatAssemblyBegin_Nest(Mat A, MatAssemblyType type)
482: {
483:   Mat_Nest *vs = (Mat_Nest *)A->data;
484:   PetscInt  i, j;
485:   PetscBool nnzstate = PETSC_FALSE;

487:   PetscFunctionBegin;
488:   for (i = 0; i < vs->nr; i++) {
489:     for (j = 0; j < vs->nc; j++) {
490:       PetscObjectState subnnzstate = 0;
491:       if (vs->m[i][j]) {
492:         PetscCall(MatAssemblyBegin(vs->m[i][j], type));
493:         if (!vs->splitassembly) {
494:           /* Note: split assembly will fail if the same block appears more than once (even indirectly through a nested
495:            * sub-block). This could be fixed by adding a flag to Mat so that there was a way to check if a Mat was
496:            * already performing an assembly, but the result would by more complicated and appears to offer less
497:            * potential for diagnostics and correctness checking. Split assembly should be fixed once there is an
498:            * interface for libraries to make asynchronous progress in "user-defined non-blocking collectives".
499:            */
500:           PetscCall(MatAssemblyEnd(vs->m[i][j], type));
501:           PetscCall(MatGetNonzeroState(vs->m[i][j], &subnnzstate));
502:         }
503:       }
504:       nnzstate                     = (PetscBool)(nnzstate || vs->nnzstate[i * vs->nc + j] != subnnzstate);
505:       vs->nnzstate[i * vs->nc + j] = subnnzstate;
506:     }
507:   }
508:   if (nnzstate) A->nonzerostate++;
509:   PetscFunctionReturn(PETSC_SUCCESS);
510: }

512: static PetscErrorCode MatAssemblyEnd_Nest(Mat A, MatAssemblyType type)
513: {
514:   Mat_Nest *vs = (Mat_Nest *)A->data;
515:   PetscInt  i, j;

517:   PetscFunctionBegin;
518:   for (i = 0; i < vs->nr; i++) {
519:     for (j = 0; j < vs->nc; j++) {
520:       if (vs->m[i][j]) {
521:         if (vs->splitassembly) PetscCall(MatAssemblyEnd(vs->m[i][j], type));
522:       }
523:     }
524:   }
525:   PetscFunctionReturn(PETSC_SUCCESS);
526: }

528: static PetscErrorCode MatNestFindNonzeroSubMatRow(Mat A, PetscInt row, Mat *B)
529: {
530:   Mat_Nest *vs = (Mat_Nest *)A->data;
531:   PetscInt  j;
532:   Mat       sub;

534:   PetscFunctionBegin;
535:   sub = (row < vs->nc) ? vs->m[row][row] : (Mat)NULL; /* Prefer to find on the diagonal */
536:   for (j = 0; !sub && j < vs->nc; j++) sub = vs->m[row][j];
537:   if (sub) PetscCall(MatSetUp(sub)); /* Ensure that the sizes are available */
538:   *B = sub;
539:   PetscFunctionReturn(PETSC_SUCCESS);
540: }

542: static PetscErrorCode MatNestFindNonzeroSubMatCol(Mat A, PetscInt col, Mat *B)
543: {
544:   Mat_Nest *vs = (Mat_Nest *)A->data;
545:   PetscInt  i;
546:   Mat       sub;

548:   PetscFunctionBegin;
549:   sub = (col < vs->nr) ? vs->m[col][col] : (Mat)NULL; /* Prefer to find on the diagonal */
550:   for (i = 0; !sub && i < vs->nr; i++) sub = vs->m[i][col];
551:   if (sub) PetscCall(MatSetUp(sub)); /* Ensure that the sizes are available */
552:   *B = sub;
553:   PetscFunctionReturn(PETSC_SUCCESS);
554: }

556: static PetscErrorCode MatNestFindISRange(Mat A, PetscInt n, const IS list[], IS is, PetscInt *begin, PetscInt *end)
557: {
558:   PetscInt  i, j, size, m;
559:   PetscBool flg;
560:   IS        out, concatenate[2];

562:   PetscFunctionBegin;
563:   PetscAssertPointer(list, 3);
565:   if (begin) {
566:     PetscAssertPointer(begin, 5);
567:     *begin = -1;
568:   }
569:   if (end) {
570:     PetscAssertPointer(end, 6);
571:     *end = -1;
572:   }
573:   for (i = 0; i < n; i++) {
574:     if (!list[i]) continue;
575:     PetscCall(ISEqualUnsorted(list[i], is, &flg));
576:     if (flg) {
577:       if (begin) *begin = i;
578:       if (end) *end = i + 1;
579:       PetscFunctionReturn(PETSC_SUCCESS);
580:     }
581:   }
582:   PetscCall(ISGetSize(is, &size));
583:   for (i = 0; i < n - 1; i++) {
584:     if (!list[i]) continue;
585:     m = 0;
586:     PetscCall(ISConcatenate(PetscObjectComm((PetscObject)A), 2, list + i, &out));
587:     PetscCall(ISGetSize(out, &m));
588:     for (j = i + 2; j < n && m < size; j++) {
589:       if (list[j]) {
590:         concatenate[0] = out;
591:         concatenate[1] = list[j];
592:         PetscCall(ISConcatenate(PetscObjectComm((PetscObject)A), 2, concatenate, &out));
593:         PetscCall(ISDestroy(concatenate));
594:         PetscCall(ISGetSize(out, &m));
595:       }
596:     }
597:     if (m == size) {
598:       PetscCall(ISEqualUnsorted(out, is, &flg));
599:       if (flg) {
600:         if (begin) *begin = i;
601:         if (end) *end = j;
602:         PetscCall(ISDestroy(&out));
603:         PetscFunctionReturn(PETSC_SUCCESS);
604:       }
605:     }
606:     PetscCall(ISDestroy(&out));
607:   }
608:   PetscFunctionReturn(PETSC_SUCCESS);
609: }

611: static PetscErrorCode MatNestFillEmptyMat_Private(Mat A, PetscInt i, PetscInt j, Mat *B)
612: {
613:   Mat_Nest *vs = (Mat_Nest *)A->data;
614:   PetscInt  lr, lc;

616:   PetscFunctionBegin;
617:   PetscCall(MatCreate(PetscObjectComm((PetscObject)A), B));
618:   PetscCall(ISGetLocalSize(vs->isglobal.row[i], &lr));
619:   PetscCall(ISGetLocalSize(vs->isglobal.col[j], &lc));
620:   PetscCall(MatSetSizes(*B, lr, lc, PETSC_DECIDE, PETSC_DECIDE));
621:   PetscCall(MatSetType(*B, MATAIJ));
622:   PetscCall(MatSeqAIJSetPreallocation(*B, 0, NULL));
623:   PetscCall(MatMPIAIJSetPreallocation(*B, 0, NULL, 0, NULL));
624:   PetscCall(MatSetUp(*B));
625:   PetscCall(MatSetOption(*B, MAT_NO_OFF_PROC_ENTRIES, PETSC_TRUE));
626:   PetscCall(MatAssemblyBegin(*B, MAT_FINAL_ASSEMBLY));
627:   PetscCall(MatAssemblyEnd(*B, MAT_FINAL_ASSEMBLY));
628:   PetscFunctionReturn(PETSC_SUCCESS);
629: }

631: static PetscErrorCode MatNestGetBlock_Private(Mat A, PetscInt rbegin, PetscInt rend, PetscInt cbegin, PetscInt cend, Mat *B)
632: {
633:   Mat_Nest  *vs = (Mat_Nest *)A->data;
634:   Mat       *a;
635:   PetscInt   i, j, k, l, nr = rend - rbegin, nc = cend - cbegin;
636:   char       keyname[256];
637:   PetscBool *b;
638:   PetscBool  flg;

640:   PetscFunctionBegin;
641:   *B = NULL;
642:   PetscCall(PetscSNPrintf(keyname, sizeof(keyname), "NestBlock_%" PetscInt_FMT "-%" PetscInt_FMT "x%" PetscInt_FMT "-%" PetscInt_FMT, rbegin, rend, cbegin, cend));
643:   PetscCall(PetscObjectQuery((PetscObject)A, keyname, (PetscObject *)B));
644:   if (*B) PetscFunctionReturn(PETSC_SUCCESS);

646:   PetscCall(PetscMalloc2(nr * nc, &a, nr * nc, &b));
647:   for (i = 0; i < nr; i++) {
648:     for (j = 0; j < nc; j++) {
649:       a[i * nc + j] = vs->m[rbegin + i][cbegin + j];
650:       b[i * nc + j] = PETSC_FALSE;
651:     }
652:   }
653:   if (nc != vs->nc && nr != vs->nr) {
654:     for (i = 0; i < nr; i++) {
655:       for (j = 0; j < nc; j++) {
656:         flg = PETSC_FALSE;
657:         for (k = 0; (k < nr && !flg); k++) {
658:           if (a[j + k * nc]) flg = PETSC_TRUE;
659:         }
660:         if (flg) {
661:           flg = PETSC_FALSE;
662:           for (l = 0; (l < nc && !flg); l++) {
663:             if (a[i * nc + l]) flg = PETSC_TRUE;
664:           }
665:         }
666:         if (!flg) {
667:           b[i * nc + j] = PETSC_TRUE;
668:           PetscCall(MatNestFillEmptyMat_Private(A, rbegin + i, cbegin + j, a + i * nc + j));
669:         }
670:       }
671:     }
672:   }
673:   PetscCall(MatCreateNest(PetscObjectComm((PetscObject)A), nr, nr != vs->nr ? NULL : vs->isglobal.row, nc, nc != vs->nc ? NULL : vs->isglobal.col, a, B));
674:   for (i = 0; i < nr; i++) {
675:     for (j = 0; j < nc; j++) {
676:       if (b[i * nc + j]) PetscCall(MatDestroy(a + i * nc + j));
677:     }
678:   }
679:   PetscCall(PetscFree2(a, b));
680:   (*B)->assembled = A->assembled;
681:   PetscCall(PetscObjectCompose((PetscObject)A, keyname, (PetscObject)*B));
682:   PetscCall(PetscObjectDereference((PetscObject)*B)); /* Leave the only remaining reference in the composition */
683:   PetscFunctionReturn(PETSC_SUCCESS);
684: }

686: static PetscErrorCode MatNestFindSubMat(Mat A, struct MatNestISPair *is, IS isrow, IS iscol, Mat *B)
687: {
688:   Mat_Nest *vs = (Mat_Nest *)A->data;
689:   PetscInt  rbegin, rend, cbegin, cend;

691:   PetscFunctionBegin;
692:   PetscCall(MatNestFindISRange(A, vs->nr, is->row, isrow, &rbegin, &rend));
693:   PetscCall(MatNestFindISRange(A, vs->nc, is->col, iscol, &cbegin, &cend));
694:   if (rend == rbegin + 1 && cend == cbegin + 1) {
695:     if (!vs->m[rbegin][cbegin]) PetscCall(MatNestFillEmptyMat_Private(A, rbegin, cbegin, vs->m[rbegin] + cbegin));
696:     *B = vs->m[rbegin][cbegin];
697:   } else if (rbegin != -1 && cbegin != -1) {
698:     PetscCall(MatNestGetBlock_Private(A, rbegin, rend, cbegin, cend, B));
699:   } else SETERRQ(PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_INCOMP, "Could not find index set");
700:   PetscFunctionReturn(PETSC_SUCCESS);
701: }

703: /*
704:    TODO: This does not actually returns a submatrix we can modify
705: */
706: static PetscErrorCode MatCreateSubMatrix_Nest(Mat A, IS isrow, IS iscol, MatReuse reuse, Mat *B)
707: {
708:   Mat_Nest *vs = (Mat_Nest *)A->data;
709:   Mat       sub;

711:   PetscFunctionBegin;
712:   PetscCall(MatNestFindSubMat(A, &vs->isglobal, isrow, iscol, &sub));
713:   switch (reuse) {
714:   case MAT_INITIAL_MATRIX:
715:     if (sub) PetscCall(PetscObjectReference((PetscObject)sub));
716:     *B = sub;
717:     break;
718:   case MAT_REUSE_MATRIX:
719:     PetscCheck(sub == *B, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_WRONGSTATE, "Submatrix was not used before in this call");
720:     break;
721:   case MAT_IGNORE_MATRIX: /* Nothing to do */
722:     break;
723:   case MAT_INPLACE_MATRIX: /* Nothing to do */
724:     SETERRQ(PetscObjectComm((PetscObject)A), PETSC_ERR_SUP, "MAT_INPLACE_MATRIX is not supported yet");
725:   }
726:   PetscFunctionReturn(PETSC_SUCCESS);
727: }

729: static PetscErrorCode MatGetLocalSubMatrix_Nest(Mat A, IS isrow, IS iscol, Mat *B)
730: {
731:   Mat_Nest *vs = (Mat_Nest *)A->data;
732:   Mat       sub;

734:   PetscFunctionBegin;
735:   PetscCall(MatNestFindSubMat(A, &vs->islocal, isrow, iscol, &sub));
736:   /* We allow the submatrix to be NULL, perhaps it would be better for the user to return an empty matrix instead */
737:   if (sub) PetscCall(PetscObjectReference((PetscObject)sub));
738:   *B = sub;
739:   PetscFunctionReturn(PETSC_SUCCESS);
740: }

742: static PetscErrorCode MatRestoreLocalSubMatrix_Nest(Mat A, IS isrow, IS iscol, Mat *B)
743: {
744:   Mat_Nest *vs = (Mat_Nest *)A->data;
745:   Mat       sub;

747:   PetscFunctionBegin;
748:   PetscCall(MatNestFindSubMat(A, &vs->islocal, isrow, iscol, &sub));
749:   PetscCheck(*B == sub, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_WRONGSTATE, "Local submatrix has not been gotten");
750:   if (sub) {
751:     PetscCheck(((PetscObject)sub)->refct > 1, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_WRONGSTATE, "Local submatrix has had reference count decremented too many times");
752:     PetscCall(MatDestroy(B));
753:   }
754:   PetscFunctionReturn(PETSC_SUCCESS);
755: }

757: static PetscErrorCode MatGetDiagonal_Nest(Mat A, Vec v)
758: {
759:   Mat_Nest *bA = (Mat_Nest *)A->data;
760:   PetscInt  i;

762:   PetscFunctionBegin;
763:   for (i = 0; i < bA->nr; i++) {
764:     Vec bv;
765:     PetscCall(VecGetSubVector(v, bA->isglobal.row[i], &bv));
766:     if (bA->m[i][i]) {
767:       PetscCall(MatGetDiagonal(bA->m[i][i], bv));
768:     } else {
769:       PetscCall(VecSet(bv, 0.0));
770:     }
771:     PetscCall(VecRestoreSubVector(v, bA->isglobal.row[i], &bv));
772:   }
773:   PetscFunctionReturn(PETSC_SUCCESS);
774: }

776: static PetscErrorCode MatDiagonalScale_Nest(Mat A, Vec l, Vec r)
777: {
778:   Mat_Nest *bA = (Mat_Nest *)A->data;
779:   Vec       bl, *br;
780:   PetscInt  i, j;

782:   PetscFunctionBegin;
783:   PetscCall(PetscCalloc1(bA->nc, &br));
784:   if (r) {
785:     for (j = 0; j < bA->nc; j++) PetscCall(VecGetSubVector(r, bA->isglobal.col[j], &br[j]));
786:   }
787:   bl = NULL;
788:   for (i = 0; i < bA->nr; i++) {
789:     if (l) PetscCall(VecGetSubVector(l, bA->isglobal.row[i], &bl));
790:     for (j = 0; j < bA->nc; j++) {
791:       if (bA->m[i][j]) PetscCall(MatDiagonalScale(bA->m[i][j], bl, br[j]));
792:     }
793:     if (l) PetscCall(VecRestoreSubVector(l, bA->isglobal.row[i], &bl));
794:   }
795:   if (r) {
796:     for (j = 0; j < bA->nc; j++) PetscCall(VecRestoreSubVector(r, bA->isglobal.col[j], &br[j]));
797:   }
798:   PetscCall(PetscFree(br));
799:   PetscFunctionReturn(PETSC_SUCCESS);
800: }

802: static PetscErrorCode MatScale_Nest(Mat A, PetscScalar a)
803: {
804:   Mat_Nest *bA = (Mat_Nest *)A->data;
805:   PetscInt  i, j;

807:   PetscFunctionBegin;
808:   for (i = 0; i < bA->nr; i++) {
809:     for (j = 0; j < bA->nc; j++) {
810:       if (bA->m[i][j]) PetscCall(MatScale(bA->m[i][j], a));
811:     }
812:   }
813:   PetscFunctionReturn(PETSC_SUCCESS);
814: }

816: static PetscErrorCode MatShift_Nest(Mat A, PetscScalar a)
817: {
818:   Mat_Nest *bA = (Mat_Nest *)A->data;
819:   PetscInt  i;
820:   PetscBool nnzstate = PETSC_FALSE;

822:   PetscFunctionBegin;
823:   for (i = 0; i < bA->nr; i++) {
824:     PetscObjectState subnnzstate = 0;
825:     PetscCheck(bA->m[i][i], PetscObjectComm((PetscObject)A), PETSC_ERR_SUP, "No support for shifting an empty diagonal block, insert a matrix in block (%" PetscInt_FMT ",%" PetscInt_FMT ")", i, i);
826:     PetscCall(MatShift(bA->m[i][i], a));
827:     PetscCall(MatGetNonzeroState(bA->m[i][i], &subnnzstate));
828:     nnzstate                     = (PetscBool)(nnzstate || bA->nnzstate[i * bA->nc + i] != subnnzstate);
829:     bA->nnzstate[i * bA->nc + i] = subnnzstate;
830:   }
831:   if (nnzstate) A->nonzerostate++;
832:   PetscFunctionReturn(PETSC_SUCCESS);
833: }

835: static PetscErrorCode MatDiagonalSet_Nest(Mat A, Vec D, InsertMode is)
836: {
837:   Mat_Nest *bA = (Mat_Nest *)A->data;
838:   PetscInt  i;
839:   PetscBool nnzstate = PETSC_FALSE;

841:   PetscFunctionBegin;
842:   for (i = 0; i < bA->nr; i++) {
843:     PetscObjectState subnnzstate = 0;
844:     Vec              bv;
845:     PetscCall(VecGetSubVector(D, bA->isglobal.row[i], &bv));
846:     if (bA->m[i][i]) {
847:       PetscCall(MatDiagonalSet(bA->m[i][i], bv, is));
848:       PetscCall(MatGetNonzeroState(bA->m[i][i], &subnnzstate));
849:     }
850:     PetscCall(VecRestoreSubVector(D, bA->isglobal.row[i], &bv));
851:     nnzstate                     = (PetscBool)(nnzstate || bA->nnzstate[i * bA->nc + i] != subnnzstate);
852:     bA->nnzstate[i * bA->nc + i] = subnnzstate;
853:   }
854:   if (nnzstate) A->nonzerostate++;
855:   PetscFunctionReturn(PETSC_SUCCESS);
856: }

858: static PetscErrorCode MatSetRandom_Nest(Mat A, PetscRandom rctx)
859: {
860:   Mat_Nest *bA = (Mat_Nest *)A->data;
861:   PetscInt  i, j;

863:   PetscFunctionBegin;
864:   for (i = 0; i < bA->nr; i++) {
865:     for (j = 0; j < bA->nc; j++) {
866:       if (bA->m[i][j]) PetscCall(MatSetRandom(bA->m[i][j], rctx));
867:     }
868:   }
869:   PetscFunctionReturn(PETSC_SUCCESS);
870: }

872: static PetscErrorCode MatCreateVecs_Nest(Mat A, Vec *right, Vec *left)
873: {
874:   Mat_Nest *bA = (Mat_Nest *)A->data;
875:   Vec      *L, *R;
876:   MPI_Comm  comm;
877:   PetscInt  i, j;

879:   PetscFunctionBegin;
880:   PetscCall(PetscObjectGetComm((PetscObject)A, &comm));
881:   if (right) {
882:     /* allocate R */
883:     PetscCall(PetscMalloc1(bA->nc, &R));
884:     /* Create the right vectors */
885:     for (j = 0; j < bA->nc; j++) {
886:       for (i = 0; i < bA->nr; i++) {
887:         if (bA->m[i][j]) {
888:           PetscCall(MatCreateVecs(bA->m[i][j], &R[j], NULL));
889:           break;
890:         }
891:       }
892:       PetscCheck(i != bA->nr, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_WRONG, "Mat(Nest) contains a null column.");
893:     }
894:     PetscCall(VecCreateNest(comm, bA->nc, bA->isglobal.col, R, right));
895:     /* hand back control to the nest vector */
896:     for (j = 0; j < bA->nc; j++) PetscCall(VecDestroy(&R[j]));
897:     PetscCall(PetscFree(R));
898:   }

900:   if (left) {
901:     /* allocate L */
902:     PetscCall(PetscMalloc1(bA->nr, &L));
903:     /* Create the left vectors */
904:     for (i = 0; i < bA->nr; i++) {
905:       for (j = 0; j < bA->nc; j++) {
906:         if (bA->m[i][j]) {
907:           PetscCall(MatCreateVecs(bA->m[i][j], NULL, &L[i]));
908:           break;
909:         }
910:       }
911:       PetscCheck(j != bA->nc, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_WRONG, "Mat(Nest) contains a null row.");
912:     }

914:     PetscCall(VecCreateNest(comm, bA->nr, bA->isglobal.row, L, left));
915:     for (i = 0; i < bA->nr; i++) PetscCall(VecDestroy(&L[i]));

917:     PetscCall(PetscFree(L));
918:   }
919:   PetscFunctionReturn(PETSC_SUCCESS);
920: }

922: static PetscErrorCode MatView_Nest(Mat A, PetscViewer viewer)
923: {
924:   Mat_Nest *bA = (Mat_Nest *)A->data;
925:   PetscBool isascii, viewSub = PETSC_FALSE;
926:   PetscInt  i, j;

928:   PetscFunctionBegin;
929:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
930:   if (isascii) {
931:     PetscCall(PetscOptionsGetBool(((PetscObject)A)->options, ((PetscObject)A)->prefix, "-mat_view_nest_sub", &viewSub, NULL));
932:     PetscCall(PetscViewerASCIIPrintf(viewer, "Matrix object:\n"));
933:     PetscCall(PetscViewerASCIIPushTab(viewer));
934:     PetscCall(PetscViewerASCIIPrintf(viewer, "type=nest, rows=%" PetscInt_FMT ", cols=%" PetscInt_FMT "\n", bA->nr, bA->nc));

936:     PetscCall(PetscViewerASCIIPrintf(viewer, "MatNest structure:\n"));
937:     for (i = 0; i < bA->nr; i++) {
938:       for (j = 0; j < bA->nc; j++) {
939:         MatType   type;
940:         char      name[256] = "", prefix[256] = "";
941:         PetscInt  NR, NC;
942:         PetscBool isNest = PETSC_FALSE;

944:         if (!bA->m[i][j]) {
945:           PetscCall(PetscViewerASCIIPrintf(viewer, "(%" PetscInt_FMT ",%" PetscInt_FMT ") : NULL\n", i, j));
946:           continue;
947:         }
948:         PetscCall(MatGetSize(bA->m[i][j], &NR, &NC));
949:         PetscCall(MatGetType(bA->m[i][j], &type));
950:         if (((PetscObject)bA->m[i][j])->name) PetscCall(PetscSNPrintf(name, sizeof(name), "name=\"%s\", ", ((PetscObject)bA->m[i][j])->name));
951:         if (((PetscObject)bA->m[i][j])->prefix) PetscCall(PetscSNPrintf(prefix, sizeof(prefix), "prefix=\"%s\", ", ((PetscObject)bA->m[i][j])->prefix));
952:         PetscCall(PetscObjectTypeCompare((PetscObject)bA->m[i][j], MATNEST, &isNest));

954:         PetscCall(PetscViewerASCIIPrintf(viewer, "(%" PetscInt_FMT ",%" PetscInt_FMT ") : %s%stype=%s, rows=%" PetscInt_FMT ", cols=%" PetscInt_FMT "\n", i, j, name, prefix, type, NR, NC));

956:         if (isNest || viewSub) {
957:           PetscCall(PetscViewerASCIIPushTab(viewer)); /* push1 */
958:           PetscCall(MatView(bA->m[i][j], viewer));
959:           PetscCall(PetscViewerASCIIPopTab(viewer)); /* pop1 */
960:         }
961:       }
962:     }
963:     PetscCall(PetscViewerASCIIPopTab(viewer)); /* pop0 */
964:   }
965:   PetscFunctionReturn(PETSC_SUCCESS);
966: }

968: static PetscErrorCode MatZeroEntries_Nest(Mat A)
969: {
970:   Mat_Nest *bA = (Mat_Nest *)A->data;
971:   PetscInt  i, j;

973:   PetscFunctionBegin;
974:   for (i = 0; i < bA->nr; i++) {
975:     for (j = 0; j < bA->nc; j++) {
976:       if (!bA->m[i][j]) continue;
977:       PetscCall(MatZeroEntries(bA->m[i][j]));
978:     }
979:   }
980:   PetscFunctionReturn(PETSC_SUCCESS);
981: }

983: static PetscErrorCode MatCopy_Nest(Mat A, Mat B, MatStructure str)
984: {
985:   Mat_Nest *bA = (Mat_Nest *)A->data, *bB = (Mat_Nest *)B->data;
986:   PetscInt  i, j, nr = bA->nr, nc = bA->nc;
987:   PetscBool nnzstate = PETSC_FALSE;

989:   PetscFunctionBegin;
990:   PetscCheck(nr == bB->nr && nc == bB->nc, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_INCOMP, "Cannot copy a Mat_Nest of block size (%" PetscInt_FMT ",%" PetscInt_FMT ") to a Mat_Nest of block size (%" PetscInt_FMT ",%" PetscInt_FMT ")", bB->nr, bB->nc, nr, nc);
991:   for (i = 0; i < nr; i++) {
992:     for (j = 0; j < nc; j++) {
993:       PetscObjectState subnnzstate = 0;
994:       if (bA->m[i][j] && bB->m[i][j]) {
995:         PetscCall(MatCopy(bA->m[i][j], bB->m[i][j], str));
996:       } else PetscCheck(!bA->m[i][j] && !bB->m[i][j], PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_INCOMP, "Matrix block does not exist at %" PetscInt_FMT ",%" PetscInt_FMT, i, j);
997:       PetscCall(MatGetNonzeroState(bB->m[i][j], &subnnzstate));
998:       nnzstate                 = (PetscBool)(nnzstate || bB->nnzstate[i * nc + j] != subnnzstate);
999:       bB->nnzstate[i * nc + j] = subnnzstate;
1000:     }
1001:   }
1002:   if (nnzstate) B->nonzerostate++;
1003:   PetscFunctionReturn(PETSC_SUCCESS);
1004: }

1006: static PetscErrorCode MatAXPY_Nest(Mat Y, PetscScalar a, Mat X, MatStructure str)
1007: {
1008:   Mat_Nest *bY = (Mat_Nest *)Y->data, *bX = (Mat_Nest *)X->data;
1009:   PetscInt  i, j, nr = bY->nr, nc = bY->nc;
1010:   PetscBool nnzstate = PETSC_FALSE;

1012:   PetscFunctionBegin;
1013:   PetscCheck(nr == bX->nr && nc == bX->nc, PetscObjectComm((PetscObject)Y), PETSC_ERR_ARG_INCOMP, "Cannot AXPY a MatNest of block size (%" PetscInt_FMT ",%" PetscInt_FMT ") with a MatNest of block size (%" PetscInt_FMT ",%" PetscInt_FMT ")", bX->nr, bX->nc, nr, nc);
1014:   for (i = 0; i < nr; i++) {
1015:     for (j = 0; j < nc; j++) {
1016:       PetscObjectState subnnzstate = 0;
1017:       if (bY->m[i][j] && bX->m[i][j]) {
1018:         PetscCall(MatAXPY(bY->m[i][j], a, bX->m[i][j], str));
1019:       } else if (bX->m[i][j]) {
1020:         Mat M;

1022:         PetscCheck(str == DIFFERENT_NONZERO_PATTERN || str == UNKNOWN_NONZERO_PATTERN, PetscObjectComm((PetscObject)Y), PETSC_ERR_ARG_INCOMP, "Matrix block does not exist at %" PetscInt_FMT ",%" PetscInt_FMT ". Use DIFFERENT_NONZERO_PATTERN or UNKNOWN_NONZERO_PATTERN", i, j);
1023:         PetscCall(MatDuplicate(bX->m[i][j], MAT_COPY_VALUES, &M));
1024:         PetscCall(MatNestSetSubMat(Y, i, j, M));
1025:         PetscCall(MatDestroy(&M));
1026:       }
1027:       if (bY->m[i][j]) PetscCall(MatGetNonzeroState(bY->m[i][j], &subnnzstate));
1028:       nnzstate                 = (PetscBool)(nnzstate || bY->nnzstate[i * nc + j] != subnnzstate);
1029:       bY->nnzstate[i * nc + j] = subnnzstate;
1030:     }
1031:   }
1032:   if (nnzstate) Y->nonzerostate++;
1033:   PetscFunctionReturn(PETSC_SUCCESS);
1034: }

1036: static PetscErrorCode MatDuplicate_Nest(Mat A, MatDuplicateOption op, Mat *B)
1037: {
1038:   Mat_Nest *bA = (Mat_Nest *)A->data;
1039:   Mat      *b;
1040:   PetscInt  i, j, nr = bA->nr, nc = bA->nc;

1042:   PetscFunctionBegin;
1043:   PetscCall(PetscMalloc1(nr * nc, &b));
1044:   for (i = 0; i < nr; i++) {
1045:     for (j = 0; j < nc; j++) {
1046:       if (bA->m[i][j]) {
1047:         PetscCall(MatDuplicate(bA->m[i][j], op, &b[i * nc + j]));
1048:       } else {
1049:         b[i * nc + j] = NULL;
1050:       }
1051:     }
1052:   }
1053:   PetscCall(MatCreateNest(PetscObjectComm((PetscObject)A), nr, bA->isglobal.row, nc, bA->isglobal.col, b, B));
1054:   /* Give the new MatNest exclusive ownership */
1055:   for (i = 0; i < nr * nc; i++) PetscCall(MatDestroy(&b[i]));
1056:   PetscCall(PetscFree(b));

1058:   PetscCall(MatAssemblyBegin(*B, MAT_FINAL_ASSEMBLY));
1059:   PetscCall(MatAssemblyEnd(*B, MAT_FINAL_ASSEMBLY));
1060:   PetscFunctionReturn(PETSC_SUCCESS);
1061: }

1063: /* nest api */
1064: static PetscErrorCode MatNestGetSubMat_Nest(Mat A, PetscInt idxm, PetscInt jdxm, Mat *mat)
1065: {
1066:   Mat_Nest *bA = (Mat_Nest *)A->data;

1068:   PetscFunctionBegin;
1069:   PetscCheck(idxm < bA->nr, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_OUTOFRANGE, "Row too large: row %" PetscInt_FMT " max %" PetscInt_FMT, idxm, bA->nr - 1);
1070:   PetscCheck(jdxm < bA->nc, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_OUTOFRANGE, "Col too large: row %" PetscInt_FMT " max %" PetscInt_FMT, jdxm, bA->nc - 1);
1071:   *mat = bA->m[idxm][jdxm];
1072:   PetscFunctionReturn(PETSC_SUCCESS);
1073: }

1075: /*@
1076:   MatNestGetSubMat - Returns a single, sub-matrix from a `MATNEST`

1078:   Not Collective

1080:   Input Parameters:
1081: + A    - `MATNEST` matrix
1082: . idxm - index of the matrix within the nest matrix
1083: - jdxm - index of the matrix within the nest matrix

1085:   Output Parameter:
1086: . sub - matrix at index `idxm`, `jdxm` within the nest matrix

1088:   Level: developer

1090: .seealso: [](ch_matrices), `Mat`, `MATNEST`, `MatNestGetSize()`, `MatNestGetSubMats()`, `MatCreateNest()`, `MatNestSetSubMat()`,
1091:           `MatNestGetLocalISs()`, `MatNestGetISs()`
1092: @*/
1093: PetscErrorCode MatNestGetSubMat(Mat A, PetscInt idxm, PetscInt jdxm, Mat *sub)
1094: {
1095:   PetscFunctionBegin;
1099:   PetscAssertPointer(sub, 4);
1100:   PetscUseMethod(A, "MatNestGetSubMat_C", (Mat, PetscInt, PetscInt, Mat *), (A, idxm, jdxm, sub));
1101:   PetscFunctionReturn(PETSC_SUCCESS);
1102: }

1104: static PetscErrorCode MatNestSetSubMat_Nest(Mat A, PetscInt idxm, PetscInt jdxm, Mat mat)
1105: {
1106:   Mat_Nest *bA = (Mat_Nest *)A->data;
1107:   PetscInt  m, n, M, N, mi, ni, Mi, Ni;

1109:   PetscFunctionBegin;
1110:   PetscCheck(idxm < bA->nr, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_OUTOFRANGE, "Row too large: row %" PetscInt_FMT " max %" PetscInt_FMT, idxm, bA->nr - 1);
1111:   PetscCheck(jdxm < bA->nc, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_OUTOFRANGE, "Col too large: row %" PetscInt_FMT " max %" PetscInt_FMT, jdxm, bA->nc - 1);
1112:   if (mat) {
1113:     PetscCall(MatGetLocalSize(mat, &m, &n));
1114:     PetscCall(MatGetSize(mat, &M, &N));
1115:     PetscCall(ISGetLocalSize(bA->isglobal.row[idxm], &mi));
1116:     PetscCall(ISGetSize(bA->isglobal.row[idxm], &Mi));
1117:     PetscCall(ISGetLocalSize(bA->isglobal.col[jdxm], &ni));
1118:     PetscCall(ISGetSize(bA->isglobal.col[jdxm], &Ni));
1119:     PetscCheck(M == Mi && N == Ni, PetscObjectComm((PetscObject)mat), PETSC_ERR_ARG_INCOMP, "Submatrix dimension (%" PetscInt_FMT ",%" PetscInt_FMT ") incompatible with nest block (%" PetscInt_FMT ",%" PetscInt_FMT ")", M, N, Mi, Ni);
1120:     PetscCheck(m == mi && n == ni, PetscObjectComm((PetscObject)mat), PETSC_ERR_ARG_INCOMP, "Submatrix local dimension (%" PetscInt_FMT ",%" PetscInt_FMT ") incompatible with nest block (%" PetscInt_FMT ",%" PetscInt_FMT ")", m, n, mi, ni);
1121:   }

1123:   /* do not increase object state */
1124:   if (mat == bA->m[idxm][jdxm]) PetscFunctionReturn(PETSC_SUCCESS);

1126:   PetscCall(PetscObjectReference((PetscObject)mat));
1127:   PetscCall(MatDestroy(&bA->m[idxm][jdxm]));
1128:   bA->m[idxm][jdxm] = mat;
1129:   PetscCall(PetscObjectStateIncrease((PetscObject)A));
1130:   if (mat) PetscCall(MatGetNonzeroState(mat, &bA->nnzstate[idxm * bA->nc + jdxm]));
1131:   else bA->nnzstate[idxm * bA->nc + jdxm] = 0;
1132:   A->nonzerostate++;
1133:   PetscFunctionReturn(PETSC_SUCCESS);
1134: }

1136: /*@
1137:   MatNestSetSubMat - Set a single submatrix in the `MATNEST`

1139:   Logically Collective

1141:   Input Parameters:
1142: + A    - `MATNEST` matrix
1143: . idxm - index of the matrix within the nest matrix
1144: . jdxm - index of the matrix within the nest matrix
1145: - sub  - matrix at index `idxm`, `jdxm` within the nest matrix

1147:   Level: developer

1149:   Notes:
1150:   The new submatrix must have the same size and communicator as that block of the nest.

1152:   This increments the reference count of the submatrix.

1154: .seealso: [](ch_matrices), `Mat`, `MATNEST`, `MatNestSetSubMats()`, `MatNestGetSubMats()`, `MatNestGetLocalISs()`, `MatCreateNest()`,
1155:           `MatNestGetSubMat()`, `MatNestGetISs()`, `MatNestGetSize()`
1156: @*/
1157: PetscErrorCode MatNestSetSubMat(Mat A, PetscInt idxm, PetscInt jdxm, Mat sub)
1158: {
1159:   PetscFunctionBegin;
1164:   PetscTryMethod(A, "MatNestSetSubMat_C", (Mat, PetscInt, PetscInt, Mat), (A, idxm, jdxm, sub));
1165:   PetscFunctionReturn(PETSC_SUCCESS);
1166: }

1168: static PetscErrorCode MatNestGetSubMats_Nest(Mat A, PetscInt *M, PetscInt *N, Mat ***mat)
1169: {
1170:   Mat_Nest *bA = (Mat_Nest *)A->data;

1172:   PetscFunctionBegin;
1173:   if (M) *M = bA->nr;
1174:   if (N) *N = bA->nc;
1175:   if (mat) *mat = bA->m;
1176:   PetscFunctionReturn(PETSC_SUCCESS);
1177: }

1179: /*@C
1180:   MatNestGetSubMats - Returns the entire two dimensional array of matrices defining a `MATNEST` matrix.

1182:   Not Collective

1184:   Input Parameter:
1185: . A - nest matrix

1187:   Output Parameters:
1188: + M   - number of submatrix rows in the nest matrix
1189: . N   - number of submatrix columns in the nest matrix
1190: - mat - array of matrices

1192:   Level: developer

1194:   Note:
1195:   The user should not free the array `mat`.

1197:   Fortran Notes:
1198:   This routine has a calling sequence `call MatNestGetSubMats(A, M, N, mat, ierr)`
1199:   where the space allocated for the optional argument `mat` is assumed large enough (if provided).
1200:   Matrices in `mat` are returned in row-major order, see `MatCreateNest()` for an example.

1202: .seealso: [](ch_matrices), `Mat`, `MATNEST`, `MatNestGetSize()`, `MatNestGetSubMat()`, `MatNestGetLocalISs()`, `MatCreateNest()`,
1203:           `MatNestSetSubMats()`, `MatNestGetISs()`, `MatNestSetSubMat()`
1204: @*/
1205: PetscErrorCode MatNestGetSubMats(Mat A, PetscInt *M, PetscInt *N, Mat ***mat)
1206: {
1207:   PetscFunctionBegin;
1209:   PetscUseMethod(A, "MatNestGetSubMats_C", (Mat, PetscInt *, PetscInt *, Mat ***), (A, M, N, mat));
1210:   PetscFunctionReturn(PETSC_SUCCESS);
1211: }

1213: static PetscErrorCode MatNestGetSize_Nest(Mat A, PetscInt *M, PetscInt *N)
1214: {
1215:   Mat_Nest *bA = (Mat_Nest *)A->data;

1217:   PetscFunctionBegin;
1218:   if (M) *M = bA->nr;
1219:   if (N) *N = bA->nc;
1220:   PetscFunctionReturn(PETSC_SUCCESS);
1221: }

1223: /*@
1224:   MatNestGetSize - Returns the size of the `MATNEST` matrix.

1226:   Not Collective

1228:   Input Parameter:
1229: . A - `MATNEST` matrix

1231:   Output Parameters:
1232: + M - number of rows in the nested mat
1233: - N - number of cols in the nested mat

1235:   Level: developer

1237:   Note:
1238:   `size` refers to the number of submatrices in the row and column directions of the nested matrix

1240: .seealso: [](ch_matrices), `Mat`, `MATNEST`, `MatNestGetSubMat()`, `MatNestGetSubMats()`, `MatCreateNest()`, `MatNestGetLocalISs()`,
1241:           `MatNestGetISs()`
1242: @*/
1243: PetscErrorCode MatNestGetSize(Mat A, PetscInt *M, PetscInt *N)
1244: {
1245:   PetscFunctionBegin;
1247:   PetscUseMethod(A, "MatNestGetSize_C", (Mat, PetscInt *, PetscInt *), (A, M, N));
1248:   PetscFunctionReturn(PETSC_SUCCESS);
1249: }

1251: static PetscErrorCode MatNestGetISs_Nest(Mat A, IS rows[], IS cols[])
1252: {
1253:   Mat_Nest *vs = (Mat_Nest *)A->data;
1254:   PetscInt  i;

1256:   PetscFunctionBegin;
1257:   if (rows)
1258:     for (i = 0; i < vs->nr; i++) rows[i] = vs->isglobal.row[i];
1259:   if (cols)
1260:     for (i = 0; i < vs->nc; i++) cols[i] = vs->isglobal.col[i];
1261:   PetscFunctionReturn(PETSC_SUCCESS);
1262: }

1264: /*@
1265:   MatNestGetISs - Returns the index sets partitioning the row and column spaces of a `MATNEST`

1267:   Not Collective

1269:   Input Parameter:
1270: . A - `MATNEST` matrix

1272:   Output Parameters:
1273: + rows - array of row index sets (pass `NULL` to ignore)
1274: - cols - array of column index sets (pass `NULL` to ignore)

1276:   Level: advanced

1278:   Note:
1279:   The user must have allocated arrays of the correct size. The reference count is not increased on the returned `IS`s.

1281: .seealso: [](ch_matrices), `Mat`, `MATNEST`, `MatNestGetSubMat()`, `MatNestGetSubMats()`, `MatNestGetSize()`, `MatNestGetLocalISs()`,
1282:           `MatCreateNest()`, `MatNestSetSubMats()`
1283: @*/
1284: PetscErrorCode MatNestGetISs(Mat A, IS rows[], IS cols[])
1285: {
1286:   PetscFunctionBegin;
1288:   PetscUseMethod(A, "MatNestGetISs_C", (Mat, IS[], IS[]), (A, rows, cols));
1289:   PetscFunctionReturn(PETSC_SUCCESS);
1290: }

1292: static PetscErrorCode MatNestGetLocalISs_Nest(Mat A, IS rows[], IS cols[])
1293: {
1294:   Mat_Nest *vs = (Mat_Nest *)A->data;
1295:   PetscInt  i;

1297:   PetscFunctionBegin;
1298:   if (rows)
1299:     for (i = 0; i < vs->nr; i++) rows[i] = vs->islocal.row[i];
1300:   if (cols)
1301:     for (i = 0; i < vs->nc; i++) cols[i] = vs->islocal.col[i];
1302:   PetscFunctionReturn(PETSC_SUCCESS);
1303: }

1305: /*@
1306:   MatNestGetLocalISs - Returns the index sets partitioning the row and column spaces of a `MATNEST`

1308:   Not Collective

1310:   Input Parameter:
1311: . A - `MATNEST` matrix

1313:   Output Parameters:
1314: + rows - array of row index sets (pass `NULL` to ignore)
1315: - cols - array of column index sets (pass `NULL` to ignore)

1317:   Level: advanced

1319:   Note:
1320:   The user must have allocated arrays of the correct size. The reference count is not increased on the returned `IS`s.

1322: .seealso: [](ch_matrices), `Mat`, `MATNEST`, `MatNestGetSubMat()`, `MatNestGetSubMats()`, `MatNestGetSize()`, `MatNestGetISs()`, `MatCreateNest()`,
1323:           `MatNestSetSubMats()`, `MatNestSetSubMat()`
1324: @*/
1325: PetscErrorCode MatNestGetLocalISs(Mat A, IS rows[], IS cols[])
1326: {
1327:   PetscFunctionBegin;
1329:   PetscUseMethod(A, "MatNestGetLocalISs_C", (Mat, IS[], IS[]), (A, rows, cols));
1330:   PetscFunctionReturn(PETSC_SUCCESS);
1331: }

1333: static PetscErrorCode MatNestSetVecType_Nest(Mat A, VecType vtype)
1334: {
1335:   PetscBool flg;

1337:   PetscFunctionBegin;
1338:   PetscCall(PetscStrcmp(vtype, VECNEST, &flg));
1339:   /* In reality, this only distinguishes VECNEST and "other" */
1340:   if (flg) A->ops->getvecs = MatCreateVecs_Nest;
1341:   else A->ops->getvecs = NULL;
1342:   PetscFunctionReturn(PETSC_SUCCESS);
1343: }

1345: /*@
1346:   MatNestSetVecType - Sets the type of `Vec` returned by `MatCreateVecs()`

1348:   Not Collective

1350:   Input Parameters:
1351: + A     - `MATNEST` matrix
1352: - vtype - `VecType` to use for creating vectors

1354:   Level: developer

1356: .seealso: [](ch_matrices), `Mat`, `MATNEST`, `MatCreateVecs()`, `MatCreateNest()`, `VecType`
1357: @*/
1358: PetscErrorCode MatNestSetVecType(Mat A, VecType vtype)
1359: {
1360:   PetscFunctionBegin;
1362:   PetscTryMethod(A, "MatNestSetVecType_C", (Mat, VecType), (A, vtype));
1363:   PetscFunctionReturn(PETSC_SUCCESS);
1364: }

1366: static PetscErrorCode MatNestSetSubMats_Nest(Mat A, PetscInt nr, const IS is_row[], PetscInt nc, const IS is_col[], const Mat a[])
1367: {
1368:   Mat_Nest *s = (Mat_Nest *)A->data;
1369:   PetscInt  i, j, m, n, M, N;
1370:   PetscBool cong, isstd, sametype = PETSC_FALSE;
1371:   VecType   vtype, type;

1373:   PetscFunctionBegin;
1374:   PetscCall(MatReset_Nest(A));

1376:   s->nr = nr;
1377:   s->nc = nc;

1379:   /* Create space for submatrices */
1380:   PetscCall(PetscMalloc1(nr, &s->m));
1381:   PetscCall(PetscMalloc1(nr * nc, &s->m[0]));
1382:   for (i = 0; i < nr; i++) {
1383:     s->m[i] = s->m[0] + i * nc;
1384:     for (j = 0; j < nc; j++) {
1385:       s->m[i][j] = a ? a[i * nc + j] : NULL;
1386:       PetscCall(PetscObjectReference((PetscObject)s->m[i][j]));
1387:     }
1388:   }
1389:   PetscCall(MatGetVecType(A, &vtype));
1390:   PetscCall(PetscStrcmp(vtype, VECSTANDARD, &isstd));
1391:   if (isstd) {
1392:     /* check if all blocks have the same vectype */
1393:     vtype = NULL;
1394:     for (i = 0; i < nr; i++) {
1395:       for (j = 0; j < nc; j++) {
1396:         if (s->m[i][j]) {
1397:           if (!vtype) { /* first visited block */
1398:             PetscCall(MatGetVecType(s->m[i][j], &vtype));
1399:             sametype = PETSC_TRUE;
1400:           } else if (sametype) {
1401:             PetscCall(MatGetVecType(s->m[i][j], &type));
1402:             PetscCall(PetscStrcmp(vtype, type, &sametype));
1403:           }
1404:         }
1405:       }
1406:     }
1407:     if (sametype) { /* propagate vectype */
1408:       PetscCall(MatSetVecType(A, vtype));
1409:     }
1410:   }

1412:   PetscCall(MatSetUp_NestIS_Private(A, nr, is_row, nc, is_col));

1414:   PetscCall(PetscMalloc1(nr, &s->row_len));
1415:   PetscCall(PetscMalloc1(nc, &s->col_len));
1416:   for (i = 0; i < nr; i++) s->row_len[i] = -1;
1417:   for (j = 0; j < nc; j++) s->col_len[j] = -1;

1419:   PetscCall(PetscCalloc1(nr * nc, &s->nnzstate));
1420:   for (i = 0; i < nr; i++) {
1421:     for (j = 0; j < nc; j++) {
1422:       if (s->m[i][j]) PetscCall(MatGetNonzeroState(s->m[i][j], &s->nnzstate[i * nc + j]));
1423:     }
1424:   }

1426:   PetscCall(MatNestGetSizes_Private(A, &m, &n, &M, &N));

1428:   PetscCall(PetscLayoutSetSize(A->rmap, M));
1429:   PetscCall(PetscLayoutSetLocalSize(A->rmap, m));
1430:   PetscCall(PetscLayoutSetSize(A->cmap, N));
1431:   PetscCall(PetscLayoutSetLocalSize(A->cmap, n));

1433:   PetscCall(PetscLayoutSetUp(A->rmap));
1434:   PetscCall(PetscLayoutSetUp(A->cmap));

1436:   /* disable operations that are not supported for non-square matrices,
1437:      or matrices for which is_row != is_col  */
1438:   PetscCall(MatHasCongruentLayouts(A, &cong));
1439:   if (cong && nr != nc) cong = PETSC_FALSE;
1440:   if (cong) {
1441:     for (i = 0; cong && i < nr; i++) PetscCall(ISEqualUnsorted(s->isglobal.row[i], s->isglobal.col[i], &cong));
1442:   }
1443:   if (!cong) {
1444:     A->ops->missingdiagonal = NULL;
1445:     A->ops->getdiagonal     = NULL;
1446:     A->ops->shift           = NULL;
1447:     A->ops->diagonalset     = NULL;
1448:   }

1450:   PetscCall(PetscCalloc2(nr, &s->left, nc, &s->right));
1451:   PetscCall(PetscObjectStateIncrease((PetscObject)A));
1452:   A->nonzerostate++;
1453:   PetscFunctionReturn(PETSC_SUCCESS);
1454: }

1456: /*@
1457:   MatNestSetSubMats - Sets the nested submatrices in a `MATNEST`

1459:   Collective

1461:   Input Parameters:
1462: + A      - `MATNEST` matrix
1463: . nr     - number of nested row blocks
1464: . is_row - index sets for each nested row block, or `NULL` to make contiguous
1465: . nc     - number of nested column blocks
1466: . is_col - index sets for each nested column block, or `NULL` to make contiguous
1467: - a      - array of nr*nc submatrices, or `NULL`

1469:   Level: advanced

1471:   Notes:
1472:   This always resets any block matrix information previously set.
1473:   Pass `NULL` in the corresponding entry of `a` for an empty block.

1475:   In both C and Fortran, `a` must be a row-major order array containing the matrices. See
1476:   `MatCreateNest()` for an example.

1478: .seealso: [](ch_matrices), `Mat`, `MATNEST`, `MatCreateNest()`, `MatNestSetSubMat()`, `MatNestGetSubMat()`, `MatNestGetSubMats()`
1479: @*/
1480: PetscErrorCode MatNestSetSubMats(Mat A, PetscInt nr, const IS is_row[], PetscInt nc, const IS is_col[], const Mat a[])
1481: {
1482:   PetscFunctionBegin;
1485:   PetscCheck(nr >= 0, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_OUTOFRANGE, "Number of rows cannot be negative");
1486:   if (nr && is_row) {
1487:     PetscAssertPointer(is_row, 3);
1489:   }
1491:   PetscCheck(nc >= 0, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_OUTOFRANGE, "Number of columns cannot be negative");
1492:   if (nc && is_col) {
1493:     PetscAssertPointer(is_col, 5);
1495:   }
1496:   PetscTryMethod(A, "MatNestSetSubMats_C", (Mat, PetscInt, const IS[], PetscInt, const IS[], const Mat[]), (A, nr, is_row, nc, is_col, a));
1497:   PetscFunctionReturn(PETSC_SUCCESS);
1498: }

1500: static PetscErrorCode MatNestCreateAggregateL2G_Private(Mat A, PetscInt n, const IS islocal[], const IS isglobal[], PetscBool colflg, ISLocalToGlobalMapping *ltog)
1501: {
1502:   PetscBool flg;
1503:   PetscInt  i, j, m, mi, *ix;

1505:   PetscFunctionBegin;
1506:   *ltog = NULL;
1507:   for (i = 0, m = 0, flg = PETSC_FALSE; i < n; i++) {
1508:     if (islocal[i]) {
1509:       PetscCall(ISGetLocalSize(islocal[i], &mi));
1510:       flg = PETSC_TRUE; /* We found a non-trivial entry */
1511:     } else {
1512:       PetscCall(ISGetLocalSize(isglobal[i], &mi));
1513:     }
1514:     m += mi;
1515:   }
1516:   if (!flg) PetscFunctionReturn(PETSC_SUCCESS);

1518:   PetscCall(PetscMalloc1(m, &ix));
1519:   for (i = 0, m = 0; i < n; i++) {
1520:     ISLocalToGlobalMapping smap = NULL;
1521:     Mat                    sub  = NULL;
1522:     PetscSF                sf;
1523:     PetscLayout            map;
1524:     const PetscInt        *ix2;

1526:     if (!colflg) {
1527:       PetscCall(MatNestFindNonzeroSubMatRow(A, i, &sub));
1528:     } else {
1529:       PetscCall(MatNestFindNonzeroSubMatCol(A, i, &sub));
1530:     }
1531:     if (sub) {
1532:       if (!colflg) {
1533:         PetscCall(MatGetLocalToGlobalMapping(sub, &smap, NULL));
1534:       } else {
1535:         PetscCall(MatGetLocalToGlobalMapping(sub, NULL, &smap));
1536:       }
1537:     }
1538:     /*
1539:        Now we need to extract the monolithic global indices that correspond to the given split global indices.
1540:        In many/most cases, we only want MatGetLocalSubMatrix() to work, in which case we only need to know the size of the local spaces.
1541:     */
1542:     PetscCall(ISGetIndices(isglobal[i], &ix2));
1543:     if (islocal[i]) {
1544:       PetscInt *ilocal, *iremote;
1545:       PetscInt  mil, nleaves;

1547:       PetscCall(ISGetLocalSize(islocal[i], &mi));
1548:       PetscCheck(smap, PetscObjectComm((PetscObject)A), PETSC_ERR_PLIB, "Missing local to global map");
1549:       for (j = 0; j < mi; j++) ix[m + j] = j;
1550:       PetscCall(ISLocalToGlobalMappingApply(smap, mi, ix + m, ix + m));

1552:       /* PetscSFSetGraphLayout does not like negative indices */
1553:       PetscCall(PetscMalloc2(mi, &ilocal, mi, &iremote));
1554:       for (j = 0, nleaves = 0; j < mi; j++) {
1555:         if (ix[m + j] < 0) continue;
1556:         ilocal[nleaves]  = j;
1557:         iremote[nleaves] = ix[m + j];
1558:         nleaves++;
1559:       }
1560:       PetscCall(ISGetLocalSize(isglobal[i], &mil));
1561:       PetscCall(PetscSFCreate(PetscObjectComm((PetscObject)A), &sf));
1562:       PetscCall(PetscLayoutCreate(PetscObjectComm((PetscObject)A), &map));
1563:       PetscCall(PetscLayoutSetLocalSize(map, mil));
1564:       PetscCall(PetscLayoutSetUp(map));
1565:       PetscCall(PetscSFSetGraphLayout(sf, map, nleaves, ilocal, PETSC_USE_POINTER, iremote));
1566:       PetscCall(PetscLayoutDestroy(&map));
1567:       PetscCall(PetscSFBcastBegin(sf, MPIU_INT, ix2, ix + m, MPI_REPLACE));
1568:       PetscCall(PetscSFBcastEnd(sf, MPIU_INT, ix2, ix + m, MPI_REPLACE));
1569:       PetscCall(PetscSFDestroy(&sf));
1570:       PetscCall(PetscFree2(ilocal, iremote));
1571:     } else {
1572:       PetscCall(ISGetLocalSize(isglobal[i], &mi));
1573:       for (j = 0; j < mi; j++) ix[m + j] = ix2[i];
1574:     }
1575:     PetscCall(ISRestoreIndices(isglobal[i], &ix2));
1576:     m += mi;
1577:   }
1578:   PetscCall(ISLocalToGlobalMappingCreate(PetscObjectComm((PetscObject)A), 1, m, ix, PETSC_OWN_POINTER, ltog));
1579:   PetscFunctionReturn(PETSC_SUCCESS);
1580: }

1582: /* If an IS was provided, there is nothing Nest needs to do, otherwise Nest will build a strided IS */
1583: /*
1584:   nprocessors = NP
1585:   Nest x^T = ((g_0,g_1,...g_nprocs-1), (h_0,h_1,...h_NP-1))
1586:        proc 0: => (g_0,h_0,)
1587:        proc 1: => (g_1,h_1,)
1588:        ...
1589:        proc nprocs-1: => (g_NP-1,h_NP-1,)

1591:             proc 0:                      proc 1:                    proc nprocs-1:
1592:     is[0] = (0,1,2,...,nlocal(g_0)-1)  (0,1,...,nlocal(g_1)-1)  (0,1,...,nlocal(g_NP-1))

1594:             proc 0:
1595:     is[1] = (nlocal(g_0),nlocal(g_0)+1,...,nlocal(g_0)+nlocal(h_0)-1)
1596:             proc 1:
1597:     is[1] = (nlocal(g_1),nlocal(g_1)+1,...,nlocal(g_1)+nlocal(h_1)-1)

1599:             proc NP-1:
1600:     is[1] = (nlocal(g_NP-1),nlocal(g_NP-1)+1,...,nlocal(g_NP-1)+nlocal(h_NP-1)-1)
1601: */
1602: static PetscErrorCode MatSetUp_NestIS_Private(Mat A, PetscInt nr, const IS is_row[], PetscInt nc, const IS is_col[])
1603: {
1604:   Mat_Nest *vs = (Mat_Nest *)A->data;
1605:   PetscInt  i, j, offset, n, nsum, bs;
1606:   Mat       sub = NULL;

1608:   PetscFunctionBegin;
1609:   PetscCall(PetscMalloc1(nr, &vs->isglobal.row));
1610:   PetscCall(PetscMalloc1(nc, &vs->isglobal.col));
1611:   if (is_row) { /* valid IS is passed in */
1612:     /* refs on is[] are incremented */
1613:     for (i = 0; i < vs->nr; i++) {
1614:       PetscCall(PetscObjectReference((PetscObject)is_row[i]));

1616:       vs->isglobal.row[i] = is_row[i];
1617:     }
1618:   } else { /* Create the ISs by inspecting sizes of a submatrix in each row */
1619:     nsum = 0;
1620:     for (i = 0; i < vs->nr; i++) { /* Add up the local sizes to compute the aggregate offset */
1621:       PetscCall(MatNestFindNonzeroSubMatRow(A, i, &sub));
1622:       PetscCheck(sub, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_WRONG, "No nonzero submatrix in row %" PetscInt_FMT, i);
1623:       PetscCall(MatGetLocalSize(sub, &n, NULL));
1624:       PetscCheck(n >= 0, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_WRONGSTATE, "Sizes have not yet been set for submatrix");
1625:       nsum += n;
1626:     }
1627:     PetscCallMPI(MPI_Scan(&nsum, &offset, 1, MPIU_INT, MPI_SUM, PetscObjectComm((PetscObject)A)));
1628:     offset -= nsum;
1629:     for (i = 0; i < vs->nr; i++) {
1630:       PetscCall(MatNestFindNonzeroSubMatRow(A, i, &sub));
1631:       PetscCall(MatGetLocalSize(sub, &n, NULL));
1632:       PetscCall(MatGetBlockSizes(sub, &bs, NULL));
1633:       PetscCall(ISCreateStride(PetscObjectComm((PetscObject)sub), n, offset, 1, &vs->isglobal.row[i]));
1634:       PetscCall(ISSetBlockSize(vs->isglobal.row[i], bs));
1635:       offset += n;
1636:     }
1637:   }

1639:   if (is_col) { /* valid IS is passed in */
1640:     /* refs on is[] are incremented */
1641:     for (j = 0; j < vs->nc; j++) {
1642:       PetscCall(PetscObjectReference((PetscObject)is_col[j]));

1644:       vs->isglobal.col[j] = is_col[j];
1645:     }
1646:   } else { /* Create the ISs by inspecting sizes of a submatrix in each column */
1647:     offset = A->cmap->rstart;
1648:     nsum   = 0;
1649:     for (j = 0; j < vs->nc; j++) {
1650:       PetscCall(MatNestFindNonzeroSubMatCol(A, j, &sub));
1651:       PetscCheck(sub, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_WRONG, "No nonzero submatrix in column %" PetscInt_FMT, i);
1652:       PetscCall(MatGetLocalSize(sub, NULL, &n));
1653:       PetscCheck(n >= 0, PetscObjectComm((PetscObject)A), PETSC_ERR_ARG_WRONGSTATE, "Sizes have not yet been set for submatrix");
1654:       nsum += n;
1655:     }
1656:     PetscCallMPI(MPI_Scan(&nsum, &offset, 1, MPIU_INT, MPI_SUM, PetscObjectComm((PetscObject)A)));
1657:     offset -= nsum;
1658:     for (j = 0; j < vs->nc; j++) {
1659:       PetscCall(MatNestFindNonzeroSubMatCol(A, j, &sub));
1660:       PetscCall(MatGetLocalSize(sub, NULL, &n));
1661:       PetscCall(MatGetBlockSizes(sub, NULL, &bs));
1662:       PetscCall(ISCreateStride(PetscObjectComm((PetscObject)sub), n, offset, 1, &vs->isglobal.col[j]));
1663:       PetscCall(ISSetBlockSize(vs->isglobal.col[j], bs));
1664:       offset += n;
1665:     }
1666:   }

1668:   /* Set up the local ISs */
1669:   PetscCall(PetscMalloc1(vs->nr, &vs->islocal.row));
1670:   PetscCall(PetscMalloc1(vs->nc, &vs->islocal.col));
1671:   for (i = 0, offset = 0; i < vs->nr; i++) {
1672:     IS                     isloc;
1673:     ISLocalToGlobalMapping rmap = NULL;
1674:     PetscInt               nlocal, bs;
1675:     PetscCall(MatNestFindNonzeroSubMatRow(A, i, &sub));
1676:     if (sub) PetscCall(MatGetLocalToGlobalMapping(sub, &rmap, NULL));
1677:     if (rmap) {
1678:       PetscCall(MatGetBlockSizes(sub, &bs, NULL));
1679:       PetscCall(ISLocalToGlobalMappingGetSize(rmap, &nlocal));
1680:       PetscCall(ISCreateStride(PETSC_COMM_SELF, nlocal, offset, 1, &isloc));
1681:       PetscCall(ISSetBlockSize(isloc, bs));
1682:     } else {
1683:       nlocal = 0;
1684:       isloc  = NULL;
1685:     }
1686:     vs->islocal.row[i] = isloc;
1687:     offset += nlocal;
1688:   }
1689:   for (i = 0, offset = 0; i < vs->nc; i++) {
1690:     IS                     isloc;
1691:     ISLocalToGlobalMapping cmap = NULL;
1692:     PetscInt               nlocal, bs;
1693:     PetscCall(MatNestFindNonzeroSubMatCol(A, i, &sub));
1694:     if (sub) PetscCall(MatGetLocalToGlobalMapping(sub, NULL, &cmap));
1695:     if (cmap) {
1696:       PetscCall(MatGetBlockSizes(sub, NULL, &bs));
1697:       PetscCall(ISLocalToGlobalMappingGetSize(cmap, &nlocal));
1698:       PetscCall(ISCreateStride(PETSC_COMM_SELF, nlocal, offset, 1, &isloc));
1699:       PetscCall(ISSetBlockSize(isloc, bs));
1700:     } else {
1701:       nlocal = 0;
1702:       isloc  = NULL;
1703:     }
1704:     vs->islocal.col[i] = isloc;
1705:     offset += nlocal;
1706:   }

1708:   /* Set up the aggregate ISLocalToGlobalMapping */
1709:   {
1710:     ISLocalToGlobalMapping rmap, cmap;
1711:     PetscCall(MatNestCreateAggregateL2G_Private(A, vs->nr, vs->islocal.row, vs->isglobal.row, PETSC_FALSE, &rmap));
1712:     PetscCall(MatNestCreateAggregateL2G_Private(A, vs->nc, vs->islocal.col, vs->isglobal.col, PETSC_TRUE, &cmap));
1713:     if (rmap && cmap) PetscCall(MatSetLocalToGlobalMapping(A, rmap, cmap));
1714:     PetscCall(ISLocalToGlobalMappingDestroy(&rmap));
1715:     PetscCall(ISLocalToGlobalMappingDestroy(&cmap));
1716:   }

1718:   if (PetscDefined(USE_DEBUG)) {
1719:     for (i = 0; i < vs->nr; i++) {
1720:       for (j = 0; j < vs->nc; j++) {
1721:         PetscInt m, n, M, N, mi, ni, Mi, Ni;
1722:         Mat      B = vs->m[i][j];
1723:         if (!B) continue;
1724:         PetscCall(MatGetSize(B, &M, &N));
1725:         PetscCall(MatGetLocalSize(B, &m, &n));
1726:         PetscCall(ISGetSize(vs->isglobal.row[i], &Mi));
1727:         PetscCall(ISGetSize(vs->isglobal.col[j], &Ni));
1728:         PetscCall(ISGetLocalSize(vs->isglobal.row[i], &mi));
1729:         PetscCall(ISGetLocalSize(vs->isglobal.col[j], &ni));
1730:         PetscCheck(M == Mi && N == Ni, PetscObjectComm((PetscObject)sub), PETSC_ERR_ARG_INCOMP, "Global sizes (%" PetscInt_FMT ",%" PetscInt_FMT ") of nested submatrix (%" PetscInt_FMT ",%" PetscInt_FMT ") do not agree with space defined by index sets (%" PetscInt_FMT ",%" PetscInt_FMT ")", M, N, i, j, Mi, Ni);
1731:         PetscCheck(m == mi && n == ni, PetscObjectComm((PetscObject)sub), PETSC_ERR_ARG_INCOMP, "Local sizes (%" PetscInt_FMT ",%" PetscInt_FMT ") of nested submatrix (%" PetscInt_FMT ",%" PetscInt_FMT ") do not agree with space defined by index sets (%" PetscInt_FMT ",%" PetscInt_FMT ")", m, n, i, j, mi, ni);
1732:       }
1733:     }
1734:   }

1736:   /* Set A->assembled if all non-null blocks are currently assembled */
1737:   for (i = 0; i < vs->nr; i++) {
1738:     for (j = 0; j < vs->nc; j++) {
1739:       if (vs->m[i][j] && !vs->m[i][j]->assembled) PetscFunctionReturn(PETSC_SUCCESS);
1740:     }
1741:   }
1742:   A->assembled = PETSC_TRUE;
1743:   PetscFunctionReturn(PETSC_SUCCESS);
1744: }

1746: /*@C
1747:   MatCreateNest - Creates a new `MATNEST` matrix containing several nested submatrices, each stored separately

1749:   Collective

1751:   Input Parameters:
1752: + comm   - Communicator for the new `MATNEST`
1753: . nr     - number of nested row blocks
1754: . is_row - index sets for each nested row block, or `NULL` to make contiguous
1755: . nc     - number of nested column blocks
1756: . is_col - index sets for each nested column block, or `NULL` to make contiguous
1757: - a      - array of nr*nc submatrices, empty submatrices can be passed using `NULL`

1759:   Output Parameter:
1760: . B - new matrix

1762:   Note:
1763:   In both C and Fortran, `a` must be a row-major order array holding references to the matrices.
1764:   For instance, to represent the matrix
1765:   $\begin{bmatrix} A_{11} & A_{12} \\ A_{21} & A_{22}\end{bmatrix}$
1766:   one should use `Mat a[4]={A11,A12,A21,A22}`.

1768:   Level: advanced

1770: .seealso: [](ch_matrices), `Mat`, `MATNEST`, `MatCreate()`, `VecCreateNest()`, `DMCreateMatrix()`, `MatNestSetSubMat()`,
1771:           `MatNestGetSubMat()`, `MatNestGetLocalISs()`, `MatNestGetSize()`,
1772:           `MatNestGetISs()`, `MatNestSetSubMats()`, `MatNestGetSubMats()`
1773: @*/
1774: PetscErrorCode MatCreateNest(MPI_Comm comm, PetscInt nr, const IS is_row[], PetscInt nc, const IS is_col[], const Mat a[], Mat *B)
1775: {
1776:   PetscFunctionBegin;
1777:   PetscCall(MatCreate(comm, B));
1778:   PetscCall(MatSetType(*B, MATNEST));
1779:   (*B)->preallocated = PETSC_TRUE;
1780:   PetscCall(MatNestSetSubMats(*B, nr, is_row, nc, is_col, a));
1781:   PetscFunctionReturn(PETSC_SUCCESS);
1782: }

1784: static PetscErrorCode MatConvert_Nest_SeqAIJ_fast(Mat A, MatType newtype, MatReuse reuse, Mat *newmat)
1785: {
1786:   Mat_Nest     *nest = (Mat_Nest *)A->data;
1787:   Mat          *trans;
1788:   PetscScalar **avv;
1789:   PetscScalar  *vv;
1790:   PetscInt    **aii, **ajj;
1791:   PetscInt     *ii, *jj, *ci;
1792:   PetscInt      nr, nc, nnz, i, j;
1793:   PetscBool     done;

1795:   PetscFunctionBegin;
1796:   PetscCall(MatGetSize(A, &nr, &nc));
1797:   if (reuse == MAT_REUSE_MATRIX) {
1798:     PetscInt rnr;

1800:     PetscCall(MatGetRowIJ(*newmat, 0, PETSC_FALSE, PETSC_FALSE, &rnr, (const PetscInt **)&ii, (const PetscInt **)&jj, &done));
1801:     PetscCheck(done, PetscObjectComm((PetscObject)A), PETSC_ERR_PLIB, "MatGetRowIJ");
1802:     PetscCheck(rnr == nr, PetscObjectComm((PetscObject)A), PETSC_ERR_USER, "Cannot reuse matrix, wrong number of rows");
1803:     PetscCall(MatSeqAIJGetArray(*newmat, &vv));
1804:   }
1805:   /* extract CSR for nested SeqAIJ matrices */
1806:   nnz = 0;
1807:   PetscCall(PetscCalloc4(nest->nr * nest->nc, &aii, nest->nr * nest->nc, &ajj, nest->nr * nest->nc, &avv, nest->nr * nest->nc, &trans));
1808:   for (i = 0; i < nest->nr; ++i) {
1809:     for (j = 0; j < nest->nc; ++j) {
1810:       Mat B = nest->m[i][j];
1811:       if (B) {
1812:         PetscScalar *naa;
1813:         PetscInt    *nii, *njj, nnr;
1814:         PetscBool    istrans;

1816:         PetscCall(PetscObjectTypeCompare((PetscObject)B, MATTRANSPOSEVIRTUAL, &istrans));
1817:         if (istrans) {
1818:           Mat Bt;

1820:           PetscCall(MatTransposeGetMat(B, &Bt));
1821:           PetscCall(MatTranspose(Bt, MAT_INITIAL_MATRIX, &trans[i * nest->nc + j]));
1822:           B = trans[i * nest->nc + j];
1823:         } else {
1824:           PetscCall(PetscObjectTypeCompare((PetscObject)B, MATHERMITIANTRANSPOSEVIRTUAL, &istrans));
1825:           if (istrans) {
1826:             Mat Bt;

1828:             PetscCall(MatHermitianTransposeGetMat(B, &Bt));
1829:             PetscCall(MatHermitianTranspose(Bt, MAT_INITIAL_MATRIX, &trans[i * nest->nc + j]));
1830:             B = trans[i * nest->nc + j];
1831:           }
1832:         }
1833:         PetscCall(MatGetRowIJ(B, 0, PETSC_FALSE, PETSC_FALSE, &nnr, (const PetscInt **)&nii, (const PetscInt **)&njj, &done));
1834:         PetscCheck(done, PetscObjectComm((PetscObject)B), PETSC_ERR_PLIB, "MatGetRowIJ");
1835:         PetscCall(MatSeqAIJGetArray(B, &naa));
1836:         nnz += nii[nnr];

1838:         aii[i * nest->nc + j] = nii;
1839:         ajj[i * nest->nc + j] = njj;
1840:         avv[i * nest->nc + j] = naa;
1841:       }
1842:     }
1843:   }
1844:   if (reuse != MAT_REUSE_MATRIX) {
1845:     PetscCall(PetscMalloc1(nr + 1, &ii));
1846:     PetscCall(PetscMalloc1(nnz, &jj));
1847:     PetscCall(PetscMalloc1(nnz, &vv));
1848:   } else {
1849:     PetscCheck(nnz == ii[nr], PetscObjectComm((PetscObject)A), PETSC_ERR_USER, "Cannot reuse matrix, wrong number of nonzeros");
1850:   }

1852:   /* new row pointer */
1853:   PetscCall(PetscArrayzero(ii, nr + 1));
1854:   for (i = 0; i < nest->nr; ++i) {
1855:     PetscInt ncr, rst;

1857:     PetscCall(ISStrideGetInfo(nest->isglobal.row[i], &rst, NULL));
1858:     PetscCall(ISGetLocalSize(nest->isglobal.row[i], &ncr));
1859:     for (j = 0; j < nest->nc; ++j) {
1860:       if (aii[i * nest->nc + j]) {
1861:         PetscInt *nii = aii[i * nest->nc + j];
1862:         PetscInt  ir;

1864:         for (ir = rst; ir < ncr + rst; ++ir) {
1865:           ii[ir + 1] += nii[1] - nii[0];
1866:           nii++;
1867:         }
1868:       }
1869:     }
1870:   }
1871:   for (i = 0; i < nr; i++) ii[i + 1] += ii[i];

1873:   /* construct CSR for the new matrix */
1874:   PetscCall(PetscCalloc1(nr, &ci));
1875:   for (i = 0; i < nest->nr; ++i) {
1876:     PetscInt ncr, rst;

1878:     PetscCall(ISStrideGetInfo(nest->isglobal.row[i], &rst, NULL));
1879:     PetscCall(ISGetLocalSize(nest->isglobal.row[i], &ncr));
1880:     for (j = 0; j < nest->nc; ++j) {
1881:       if (aii[i * nest->nc + j]) {
1882:         PetscScalar *nvv = avv[i * nest->nc + j], vscale = 1.0, vshift = 0.0;
1883:         PetscInt    *nii = aii[i * nest->nc + j];
1884:         PetscInt    *njj = ajj[i * nest->nc + j];
1885:         PetscInt     ir, cst;

1887:         if (trans[i * nest->nc + j]) {
1888:           vscale = ((Mat_Shell *)nest->m[i][j]->data)->vscale;
1889:           vshift = ((Mat_Shell *)nest->m[i][j]->data)->vshift;
1890:         }
1891:         PetscCall(ISStrideGetInfo(nest->isglobal.col[j], &cst, NULL));
1892:         for (ir = rst; ir < ncr + rst; ++ir) {
1893:           PetscInt ij, rsize = nii[1] - nii[0], ist = ii[ir] + ci[ir];

1895:           for (ij = 0; ij < rsize; ij++) {
1896:             jj[ist + ij] = *njj + cst;
1897:             vv[ist + ij] = vscale * *nvv;
1898:             if (PetscUnlikely(vshift != 0.0 && *njj == ir - rst)) vv[ist + ij] += vshift;
1899:             njj++;
1900:             nvv++;
1901:           }
1902:           ci[ir] += rsize;
1903:           nii++;
1904:         }
1905:       }
1906:     }
1907:   }
1908:   PetscCall(PetscFree(ci));

1910:   /* restore info */
1911:   for (i = 0; i < nest->nr; ++i) {
1912:     for (j = 0; j < nest->nc; ++j) {
1913:       Mat B = nest->m[i][j];
1914:       if (B) {
1915:         PetscInt nnr = 0, k = i * nest->nc + j;

1917:         B = (trans[k] ? trans[k] : B);
1918:         PetscCall(MatRestoreRowIJ(B, 0, PETSC_FALSE, PETSC_FALSE, &nnr, (const PetscInt **)&aii[k], (const PetscInt **)&ajj[k], &done));
1919:         PetscCheck(done, PetscObjectComm((PetscObject)B), PETSC_ERR_PLIB, "MatRestoreRowIJ");
1920:         PetscCall(MatSeqAIJRestoreArray(B, &avv[k]));
1921:         PetscCall(MatDestroy(&trans[k]));
1922:       }
1923:     }
1924:   }
1925:   PetscCall(PetscFree4(aii, ajj, avv, trans));

1927:   /* finalize newmat */
1928:   if (reuse == MAT_INITIAL_MATRIX) {
1929:     PetscCall(MatCreateSeqAIJWithArrays(PetscObjectComm((PetscObject)A), nr, nc, ii, jj, vv, newmat));
1930:   } else if (reuse == MAT_INPLACE_MATRIX) {
1931:     Mat B;

1933:     PetscCall(MatCreateSeqAIJWithArrays(PetscObjectComm((PetscObject)A), nr, nc, ii, jj, vv, &B));
1934:     PetscCall(MatHeaderReplace(A, &B));
1935:   }
1936:   PetscCall(MatAssemblyBegin(*newmat, MAT_FINAL_ASSEMBLY));
1937:   PetscCall(MatAssemblyEnd(*newmat, MAT_FINAL_ASSEMBLY));
1938:   {
1939:     Mat_SeqAIJ *a = (Mat_SeqAIJ *)((*newmat)->data);
1940:     a->free_a     = PETSC_TRUE;
1941:     a->free_ij    = PETSC_TRUE;
1942:   }
1943:   PetscFunctionReturn(PETSC_SUCCESS);
1944: }

1946: PETSC_INTERN PetscErrorCode MatAXPY_Dense_Nest(Mat Y, PetscScalar a, Mat X)
1947: {
1948:   Mat_Nest *nest = (Mat_Nest *)X->data;
1949:   PetscInt  i, j, k, rstart;
1950:   PetscBool flg;

1952:   PetscFunctionBegin;
1953:   /* Fill by row */
1954:   for (j = 0; j < nest->nc; ++j) {
1955:     /* Using global column indices and ISAllGather() is not scalable. */
1956:     IS              bNis;
1957:     PetscInt        bN;
1958:     const PetscInt *bNindices;
1959:     PetscCall(ISAllGather(nest->isglobal.col[j], &bNis));
1960:     PetscCall(ISGetSize(bNis, &bN));
1961:     PetscCall(ISGetIndices(bNis, &bNindices));
1962:     for (i = 0; i < nest->nr; ++i) {
1963:       Mat             B = nest->m[i][j], D = NULL;
1964:       PetscInt        bm, br;
1965:       const PetscInt *bmindices;
1966:       if (!B) continue;
1967:       PetscCall(PetscObjectTypeCompareAny((PetscObject)B, &flg, MATTRANSPOSEVIRTUAL, MATHERMITIANTRANSPOSEVIRTUAL, ""));
1968:       if (flg) {
1969:         PetscTryMethod(B, "MatTransposeGetMat_C", (Mat, Mat *), (B, &D));
1970:         PetscTryMethod(B, "MatHermitianTransposeGetMat_C", (Mat, Mat *), (B, &D));
1971:         PetscCall(MatConvert(B, ((PetscObject)D)->type_name, MAT_INITIAL_MATRIX, &D));
1972:         B = D;
1973:       }
1974:       PetscCall(PetscObjectTypeCompareAny((PetscObject)B, &flg, MATSEQSBAIJ, MATMPISBAIJ, ""));
1975:       if (flg) {
1976:         if (D) PetscCall(MatConvert(D, MATBAIJ, MAT_INPLACE_MATRIX, &D));
1977:         else PetscCall(MatConvert(B, MATBAIJ, MAT_INITIAL_MATRIX, &D));
1978:         B = D;
1979:       }
1980:       PetscCall(ISGetLocalSize(nest->isglobal.row[i], &bm));
1981:       PetscCall(ISGetIndices(nest->isglobal.row[i], &bmindices));
1982:       PetscCall(MatGetOwnershipRange(B, &rstart, NULL));
1983:       for (br = 0; br < bm; ++br) {
1984:         PetscInt           row = bmindices[br], brncols, *cols;
1985:         const PetscInt    *brcols;
1986:         const PetscScalar *brcoldata;
1987:         PetscScalar       *vals = NULL;
1988:         PetscCall(MatGetRow(B, br + rstart, &brncols, &brcols, &brcoldata));
1989:         PetscCall(PetscMalloc1(brncols, &cols));
1990:         for (k = 0; k < brncols; k++) cols[k] = bNindices[brcols[k]];
1991:         /*
1992:           Nest blocks are required to be nonoverlapping -- otherwise nest and monolithic index layouts wouldn't match.
1993:           Thus, we could use INSERT_VALUES, but I prefer ADD_VALUES.
1994:          */
1995:         if (a != 1.0) {
1996:           PetscCall(PetscMalloc1(brncols, &vals));
1997:           for (k = 0; k < brncols; k++) vals[k] = a * brcoldata[k];
1998:           PetscCall(MatSetValues(Y, 1, &row, brncols, cols, vals, ADD_VALUES));
1999:           PetscCall(PetscFree(vals));
2000:         } else {
2001:           PetscCall(MatSetValues(Y, 1, &row, brncols, cols, brcoldata, ADD_VALUES));
2002:         }
2003:         PetscCall(MatRestoreRow(B, br + rstart, &brncols, &brcols, &brcoldata));
2004:         PetscCall(PetscFree(cols));
2005:       }
2006:       if (D) PetscCall(MatDestroy(&D));
2007:       PetscCall(ISRestoreIndices(nest->isglobal.row[i], &bmindices));
2008:     }
2009:     PetscCall(ISRestoreIndices(bNis, &bNindices));
2010:     PetscCall(ISDestroy(&bNis));
2011:   }
2012:   PetscCall(MatAssemblyBegin(Y, MAT_FINAL_ASSEMBLY));
2013:   PetscCall(MatAssemblyEnd(Y, MAT_FINAL_ASSEMBLY));
2014:   PetscFunctionReturn(PETSC_SUCCESS);
2015: }

2017: static PetscErrorCode MatConvert_Nest_AIJ(Mat A, MatType newtype, MatReuse reuse, Mat *newmat)
2018: {
2019:   Mat_Nest   *nest = (Mat_Nest *)A->data;
2020:   PetscInt    m, n, M, N, i, j, k, *dnnz, *onnz = NULL, rstart, cstart, cend;
2021:   PetscMPIInt size;
2022:   Mat         C;

2024:   PetscFunctionBegin;
2025:   PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)A), &size));
2026:   if (size == 1) { /* look for a special case with SeqAIJ matrices and strided-1, contiguous, blocks */
2027:     PetscInt  nf;
2028:     PetscBool fast;

2030:     PetscCall(PetscStrcmp(newtype, MATAIJ, &fast));
2031:     if (!fast) PetscCall(PetscStrcmp(newtype, MATSEQAIJ, &fast));
2032:     for (i = 0; i < nest->nr && fast; ++i) {
2033:       for (j = 0; j < nest->nc && fast; ++j) {
2034:         Mat B = nest->m[i][j];
2035:         if (B) {
2036:           PetscCall(PetscObjectTypeCompare((PetscObject)B, MATSEQAIJ, &fast));
2037:           if (!fast) {
2038:             PetscBool istrans;

2040:             PetscCall(PetscObjectTypeCompare((PetscObject)B, MATTRANSPOSEVIRTUAL, &istrans));
2041:             if (istrans) {
2042:               Mat Bt;

2044:               PetscCall(MatTransposeGetMat(B, &Bt));
2045:               PetscCall(PetscObjectTypeCompare((PetscObject)Bt, MATSEQAIJ, &fast));
2046:             } else {
2047:               PetscCall(PetscObjectTypeCompare((PetscObject)B, MATHERMITIANTRANSPOSEVIRTUAL, &istrans));
2048:               if (istrans) {
2049:                 Mat Bt;

2051:                 PetscCall(MatHermitianTransposeGetMat(B, &Bt));
2052:                 PetscCall(PetscObjectTypeCompare((PetscObject)Bt, MATSEQAIJ, &fast));
2053:               }
2054:             }
2055:             if (fast) fast = (PetscBool)(!((Mat_Shell *)B->data)->zrows && !((Mat_Shell *)B->data)->zcols && !((Mat_Shell *)B->data)->axpy && !((Mat_Shell *)B->data)->left && !((Mat_Shell *)B->data)->right && !((Mat_Shell *)B->data)->dshift);
2056:           }
2057:         }
2058:       }
2059:     }
2060:     for (i = 0, nf = 0; i < nest->nr && fast; ++i) {
2061:       PetscCall(PetscObjectTypeCompare((PetscObject)nest->isglobal.row[i], ISSTRIDE, &fast));
2062:       if (fast) {
2063:         PetscInt f, s;

2065:         PetscCall(ISStrideGetInfo(nest->isglobal.row[i], &f, &s));
2066:         if (f != nf || s != 1) {
2067:           fast = PETSC_FALSE;
2068:         } else {
2069:           PetscCall(ISGetSize(nest->isglobal.row[i], &f));
2070:           nf += f;
2071:         }
2072:       }
2073:     }
2074:     for (i = 0, nf = 0; i < nest->nc && fast; ++i) {
2075:       PetscCall(PetscObjectTypeCompare((PetscObject)nest->isglobal.col[i], ISSTRIDE, &fast));
2076:       if (fast) {
2077:         PetscInt f, s;

2079:         PetscCall(ISStrideGetInfo(nest->isglobal.col[i], &f, &s));
2080:         if (f != nf || s != 1) {
2081:           fast = PETSC_FALSE;
2082:         } else {
2083:           PetscCall(ISGetSize(nest->isglobal.col[i], &f));
2084:           nf += f;
2085:         }
2086:       }
2087:     }
2088:     if (fast) {
2089:       PetscCall(MatConvert_Nest_SeqAIJ_fast(A, newtype, reuse, newmat));
2090:       PetscFunctionReturn(PETSC_SUCCESS);
2091:     }
2092:   }
2093:   PetscCall(MatGetSize(A, &M, &N));
2094:   PetscCall(MatGetLocalSize(A, &m, &n));
2095:   PetscCall(MatGetOwnershipRangeColumn(A, &cstart, &cend));
2096:   if (reuse == MAT_REUSE_MATRIX) C = *newmat;
2097:   else {
2098:     PetscCall(MatCreate(PetscObjectComm((PetscObject)A), &C));
2099:     PetscCall(MatSetType(C, newtype));
2100:     PetscCall(MatSetSizes(C, m, n, M, N));
2101:   }
2102:   PetscCall(PetscMalloc1(2 * m, &dnnz));
2103:   if (m) {
2104:     onnz = dnnz + m;
2105:     for (k = 0; k < m; k++) {
2106:       dnnz[k] = 0;
2107:       onnz[k] = 0;
2108:     }
2109:   }
2110:   for (j = 0; j < nest->nc; ++j) {
2111:     IS              bNis;
2112:     PetscInt        bN;
2113:     const PetscInt *bNindices;
2114:     PetscBool       flg;
2115:     /* Using global column indices and ISAllGather() is not scalable. */
2116:     PetscCall(ISAllGather(nest->isglobal.col[j], &bNis));
2117:     PetscCall(ISGetSize(bNis, &bN));
2118:     PetscCall(ISGetIndices(bNis, &bNindices));
2119:     for (i = 0; i < nest->nr; ++i) {
2120:       PetscSF         bmsf;
2121:       PetscSFNode    *iremote;
2122:       Mat             B = nest->m[i][j], D = NULL;
2123:       PetscInt        bm, *sub_dnnz, *sub_onnz, br;
2124:       const PetscInt *bmindices;
2125:       if (!B) continue;
2126:       PetscCall(ISGetLocalSize(nest->isglobal.row[i], &bm));
2127:       PetscCall(ISGetIndices(nest->isglobal.row[i], &bmindices));
2128:       PetscCall(PetscSFCreate(PetscObjectComm((PetscObject)A), &bmsf));
2129:       PetscCall(PetscMalloc1(bm, &iremote));
2130:       PetscCall(PetscMalloc1(bm, &sub_dnnz));
2131:       PetscCall(PetscMalloc1(bm, &sub_onnz));
2132:       for (k = 0; k < bm; ++k) {
2133:         sub_dnnz[k] = 0;
2134:         sub_onnz[k] = 0;
2135:       }
2136:       PetscCall(PetscObjectTypeCompareAny((PetscObject)B, &flg, MATTRANSPOSEVIRTUAL, MATHERMITIANTRANSPOSEVIRTUAL, ""));
2137:       if (flg) {
2138:         PetscTryMethod(B, "MatTransposeGetMat_C", (Mat, Mat *), (B, &D));
2139:         PetscTryMethod(B, "MatHermitianTransposeGetMat_C", (Mat, Mat *), (B, &D));
2140:         PetscCall(MatConvert(B, ((PetscObject)D)->type_name, MAT_INITIAL_MATRIX, &D));
2141:         B = D;
2142:       }
2143:       PetscCall(PetscObjectTypeCompareAny((PetscObject)B, &flg, MATSEQSBAIJ, MATMPISBAIJ, ""));
2144:       if (flg) {
2145:         if (D) PetscCall(MatConvert(D, MATBAIJ, MAT_INPLACE_MATRIX, &D));
2146:         else PetscCall(MatConvert(B, MATBAIJ, MAT_INITIAL_MATRIX, &D));
2147:         B = D;
2148:       }
2149:       /*
2150:        Locate the owners for all of the locally-owned global row indices for this row block.
2151:        These determine the roots of PetscSF used to communicate preallocation data to row owners.
2152:        The roots correspond to the dnnz and onnz entries; thus, there are two roots per row.
2153:        */
2154:       PetscCall(MatGetOwnershipRange(B, &rstart, NULL));
2155:       for (br = 0; br < bm; ++br) {
2156:         PetscInt        row = bmindices[br], brncols, col;
2157:         const PetscInt *brcols;
2158:         PetscInt        rowrel   = 0; /* row's relative index on its owner rank */
2159:         PetscMPIInt     rowowner = 0;
2160:         PetscCall(PetscLayoutFindOwnerIndex(A->rmap, row, &rowowner, &rowrel));
2161:         /* how many roots  */
2162:         iremote[br].rank  = rowowner;
2163:         iremote[br].index = rowrel; /* edge from bmdnnz to dnnz */
2164:         /* get nonzero pattern */
2165:         PetscCall(MatGetRow(B, br + rstart, &brncols, &brcols, NULL));
2166:         for (k = 0; k < brncols; k++) {
2167:           col = bNindices[brcols[k]];
2168:           if (col >= A->cmap->range[rowowner] && col < A->cmap->range[rowowner + 1]) {
2169:             sub_dnnz[br]++;
2170:           } else {
2171:             sub_onnz[br]++;
2172:           }
2173:         }
2174:         PetscCall(MatRestoreRow(B, br + rstart, &brncols, &brcols, NULL));
2175:       }
2176:       if (D) PetscCall(MatDestroy(&D));
2177:       PetscCall(ISRestoreIndices(nest->isglobal.row[i], &bmindices));
2178:       /* bsf will have to take care of disposing of bedges. */
2179:       PetscCall(PetscSFSetGraph(bmsf, m, bm, NULL, PETSC_OWN_POINTER, iremote, PETSC_OWN_POINTER));
2180:       PetscCall(PetscSFReduceBegin(bmsf, MPIU_INT, sub_dnnz, dnnz, MPI_SUM));
2181:       PetscCall(PetscSFReduceEnd(bmsf, MPIU_INT, sub_dnnz, dnnz, MPI_SUM));
2182:       PetscCall(PetscSFReduceBegin(bmsf, MPIU_INT, sub_onnz, onnz, MPI_SUM));
2183:       PetscCall(PetscSFReduceEnd(bmsf, MPIU_INT, sub_onnz, onnz, MPI_SUM));
2184:       PetscCall(PetscFree(sub_dnnz));
2185:       PetscCall(PetscFree(sub_onnz));
2186:       PetscCall(PetscSFDestroy(&bmsf));
2187:     }
2188:     PetscCall(ISRestoreIndices(bNis, &bNindices));
2189:     PetscCall(ISDestroy(&bNis));
2190:   }
2191:   /* Resize preallocation if overestimated */
2192:   for (i = 0; i < m; i++) {
2193:     dnnz[i] = PetscMin(dnnz[i], A->cmap->n);
2194:     onnz[i] = PetscMin(onnz[i], A->cmap->N - A->cmap->n);
2195:   }
2196:   PetscCall(MatSeqAIJSetPreallocation(C, 0, dnnz));
2197:   PetscCall(MatMPIAIJSetPreallocation(C, 0, dnnz, 0, onnz));
2198:   PetscCall(PetscFree(dnnz));
2199:   PetscCall(MatAXPY_Dense_Nest(C, 1.0, A));
2200:   if (reuse == MAT_INPLACE_MATRIX) {
2201:     PetscCall(MatHeaderReplace(A, &C));
2202:   } else *newmat = C;
2203:   PetscFunctionReturn(PETSC_SUCCESS);
2204: }

2206: static PetscErrorCode MatConvert_Nest_Dense(Mat A, MatType newtype, MatReuse reuse, Mat *newmat)
2207: {
2208:   Mat      B;
2209:   PetscInt m, n, M, N;

2211:   PetscFunctionBegin;
2212:   PetscCall(MatGetSize(A, &M, &N));
2213:   PetscCall(MatGetLocalSize(A, &m, &n));
2214:   if (reuse == MAT_REUSE_MATRIX) {
2215:     B = *newmat;
2216:     PetscCall(MatZeroEntries(B));
2217:   } else {
2218:     PetscCall(MatCreateDense(PetscObjectComm((PetscObject)A), m, PETSC_DECIDE, M, N, NULL, &B));
2219:   }
2220:   PetscCall(MatAXPY_Dense_Nest(B, 1.0, A));
2221:   if (reuse == MAT_INPLACE_MATRIX) {
2222:     PetscCall(MatHeaderReplace(A, &B));
2223:   } else if (reuse == MAT_INITIAL_MATRIX) *newmat = B;
2224:   PetscFunctionReturn(PETSC_SUCCESS);
2225: }

2227: static PetscErrorCode MatHasOperation_Nest(Mat mat, MatOperation op, PetscBool *has)
2228: {
2229:   Mat_Nest    *bA = (Mat_Nest *)mat->data;
2230:   MatOperation opAdd;
2231:   PetscInt     i, j, nr = bA->nr, nc = bA->nc;
2232:   PetscBool    flg;

2234:   PetscFunctionBegin;
2235:   *has = PETSC_FALSE;
2236:   if (op == MATOP_MULT || op == MATOP_MULT_ADD || op == MATOP_MULT_TRANSPOSE || op == MATOP_MULT_TRANSPOSE_ADD) {
2237:     opAdd = (op == MATOP_MULT || op == MATOP_MULT_ADD ? MATOP_MULT_ADD : MATOP_MULT_TRANSPOSE_ADD);
2238:     for (j = 0; j < nc; j++) {
2239:       for (i = 0; i < nr; i++) {
2240:         if (!bA->m[i][j]) continue;
2241:         PetscCall(MatHasOperation(bA->m[i][j], opAdd, &flg));
2242:         if (!flg) PetscFunctionReturn(PETSC_SUCCESS);
2243:       }
2244:     }
2245:   }
2246:   if (((void **)mat->ops)[op]) *has = PETSC_TRUE;
2247:   PetscFunctionReturn(PETSC_SUCCESS);
2248: }

2250: /*MC
2251:   MATNEST -  "nest" - Matrix type consisting of nested submatrices, each stored separately.

2253:   Level: intermediate

2255:   Notes:
2256:   This matrix type permits scalable use of `PCFIELDSPLIT` and avoids the large memory costs of extracting submatrices.
2257:   It allows the use of symmetric and block formats for parts of multi-physics simulations.
2258:   It is usually used with `DMCOMPOSITE` and `DMCreateMatrix()`

2260:   Each of the submatrices lives on the same MPI communicator as the original nest matrix (though they can have zero
2261:   rows/columns on some processes.) Thus this is not meant for cases where the submatrices live on far fewer processes
2262:   than the nest matrix.

2264: .seealso: [](ch_matrices), `Mat`, `MATNEST`, `MatCreate()`, `MatType`, `MatCreateNest()`, `MatNestSetSubMat()`, `MatNestGetSubMat()`,
2265:           `VecCreateNest()`, `DMCreateMatrix()`, `DMCOMPOSITE`, `MatNestSetVecType()`, `MatNestGetLocalISs()`,
2266:           `MatNestGetISs()`, `MatNestSetSubMats()`, `MatNestGetSubMats()`
2267: M*/
2268: PETSC_EXTERN PetscErrorCode MatCreate_Nest(Mat A)
2269: {
2270:   Mat_Nest *s;

2272:   PetscFunctionBegin;
2273:   PetscCall(PetscNew(&s));
2274:   A->data = (void *)s;

2276:   s->nr            = -1;
2277:   s->nc            = -1;
2278:   s->m             = NULL;
2279:   s->splitassembly = PETSC_FALSE;

2281:   PetscCall(PetscMemzero(A->ops, sizeof(*A->ops)));

2283:   A->ops->mult                      = MatMult_Nest;
2284:   A->ops->multadd                   = MatMultAdd_Nest;
2285:   A->ops->multtranspose             = MatMultTranspose_Nest;
2286:   A->ops->multtransposeadd          = MatMultTransposeAdd_Nest;
2287:   A->ops->transpose                 = MatTranspose_Nest;
2288:   A->ops->multhermitiantranspose    = MatMultHermitianTranspose_Nest;
2289:   A->ops->multhermitiantransposeadd = MatMultHermitianTransposeAdd_Nest;
2290:   A->ops->assemblybegin             = MatAssemblyBegin_Nest;
2291:   A->ops->assemblyend               = MatAssemblyEnd_Nest;
2292:   A->ops->zeroentries               = MatZeroEntries_Nest;
2293:   A->ops->copy                      = MatCopy_Nest;
2294:   A->ops->axpy                      = MatAXPY_Nest;
2295:   A->ops->duplicate                 = MatDuplicate_Nest;
2296:   A->ops->createsubmatrix           = MatCreateSubMatrix_Nest;
2297:   A->ops->destroy                   = MatDestroy_Nest;
2298:   A->ops->view                      = MatView_Nest;
2299:   A->ops->getvecs                   = NULL; /* Use VECNEST by calling MatNestSetVecType(A,VECNEST) */
2300:   A->ops->getlocalsubmatrix         = MatGetLocalSubMatrix_Nest;
2301:   A->ops->restorelocalsubmatrix     = MatRestoreLocalSubMatrix_Nest;
2302:   A->ops->getdiagonal               = MatGetDiagonal_Nest;
2303:   A->ops->diagonalscale             = MatDiagonalScale_Nest;
2304:   A->ops->scale                     = MatScale_Nest;
2305:   A->ops->shift                     = MatShift_Nest;
2306:   A->ops->diagonalset               = MatDiagonalSet_Nest;
2307:   A->ops->setrandom                 = MatSetRandom_Nest;
2308:   A->ops->hasoperation              = MatHasOperation_Nest;
2309:   A->ops->missingdiagonal           = MatMissingDiagonal_Nest;

2311:   A->spptr     = NULL;
2312:   A->assembled = PETSC_FALSE;

2314:   /* expose Nest api's */
2315:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestGetSubMat_C", MatNestGetSubMat_Nest));
2316:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestSetSubMat_C", MatNestSetSubMat_Nest));
2317:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestGetSubMats_C", MatNestGetSubMats_Nest));
2318:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestGetSize_C", MatNestGetSize_Nest));
2319:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestGetISs_C", MatNestGetISs_Nest));
2320:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestGetLocalISs_C", MatNestGetLocalISs_Nest));
2321:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestSetVecType_C", MatNestSetVecType_Nest));
2322:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatNestSetSubMats_C", MatNestSetSubMats_Nest));
2323:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_mpiaij_C", MatConvert_Nest_AIJ));
2324:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_seqaij_C", MatConvert_Nest_AIJ));
2325:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_aij_C", MatConvert_Nest_AIJ));
2326:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_is_C", MatConvert_Nest_IS));
2327:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_mpidense_C", MatConvert_Nest_Dense));
2328:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatConvert_nest_seqdense_C", MatConvert_Nest_Dense));
2329:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatProductSetFromOptions_nest_seqdense_C", MatProductSetFromOptions_Nest_Dense));
2330:   PetscCall(PetscObjectComposeFunction((PetscObject)A, "MatProductSetFromOptions_nest_mpidense_C", MatProductSetFromOptions_Nest_Dense));

2332:   PetscCall(PetscObjectChangeTypeName((PetscObject)A, MATNEST));
2333:   PetscFunctionReturn(PETSC_SUCCESS);
2334: }