xref: /petsc/src/mat/impls/aij/seq/matmatmult.c (revision bfe80ac4a46d58cb7760074b25f5e81b2f541d8a)
1 /*
2   Defines matrix-matrix product routines for pairs of SeqAIJ matrices
3           C = A * B
4 */
5 
6 #include <../src/mat/impls/aij/seq/aij.h> /*I "petscmat.h" I*/
7 #include <../src/mat/utils/freespace.h>
8 #include <petscbt.h>
9 #include <petsc/private/isimpl.h>
10 #include <../src/mat/impls/dense/seq/dense.h>
11 
12 PetscErrorCode MatMatMultNumeric_SeqAIJ_SeqAIJ(Mat A, Mat B, Mat C)
13 {
14   PetscFunctionBegin;
15   if (C->ops->matmultnumeric) PetscCall((*C->ops->matmultnumeric)(A, B, C));
16   else PetscCall(MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted(A, B, C));
17   PetscFunctionReturn(PETSC_SUCCESS);
18 }
19 
20 /* Modified from MatCreateSeqAIJWithArrays() */
21 PETSC_INTERN PetscErrorCode MatSetSeqAIJWithArrays_private(MPI_Comm comm, PetscInt m, PetscInt n, PetscInt i[], PetscInt j[], PetscScalar a[], MatType mtype, Mat mat)
22 {
23   PetscInt    ii;
24   Mat_SeqAIJ *aij;
25   PetscBool   isseqaij, ofree_a, ofree_ij;
26 
27   PetscFunctionBegin;
28   PetscCheck(m <= 0 || !i[0], PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "i (row indices) must start with 0");
29   PetscCall(MatSetSizes(mat, m, n, m, n));
30 
31   if (!mtype) {
32     PetscCall(PetscObjectBaseTypeCompare((PetscObject)mat, MATSEQAIJ, &isseqaij));
33     if (!isseqaij) PetscCall(MatSetType(mat, MATSEQAIJ));
34   } else {
35     PetscCall(MatSetType(mat, mtype));
36   }
37 
38   aij      = (Mat_SeqAIJ *)mat->data;
39   ofree_a  = aij->free_a;
40   ofree_ij = aij->free_ij;
41   /* changes the free flags */
42   PetscCall(MatSeqAIJSetPreallocation_SeqAIJ(mat, MAT_SKIP_ALLOCATION, NULL));
43 
44   PetscCall(PetscFree(aij->ilen));
45   PetscCall(PetscFree(aij->imax));
46   PetscCall(PetscMalloc1(m, &aij->imax));
47   PetscCall(PetscMalloc1(m, &aij->ilen));
48   for (ii = 0, aij->nonzerorowcnt = 0, aij->rmax = 0; ii < m; ii++) {
49     const PetscInt rnz = i[ii + 1] - i[ii];
50     aij->nonzerorowcnt += !!rnz;
51     aij->rmax     = PetscMax(aij->rmax, rnz);
52     aij->ilen[ii] = aij->imax[ii] = i[ii + 1] - i[ii];
53   }
54   aij->maxnz = i[m];
55   aij->nz    = i[m];
56 
57   if (ofree_a) PetscCall(PetscShmgetDeallocateArray((void **)&aij->a));
58   if (ofree_ij) PetscCall(PetscShmgetDeallocateArray((void **)&aij->j));
59   if (ofree_ij) PetscCall(PetscShmgetDeallocateArray((void **)&aij->i));
60 
61   aij->i       = i;
62   aij->j       = j;
63   aij->a       = a;
64   aij->nonew   = -1; /* this indicates that inserting a new value in the matrix that generates a new nonzero is an error */
65   aij->free_a  = PETSC_FALSE;
66   aij->free_ij = PETSC_FALSE;
67   PetscCall(MatCheckCompressedRow(mat, aij->nonzerorowcnt, &aij->compressedrow, aij->i, m, 0.6));
68   // Always build the diag info when i, j are set
69   PetscCall(MatMarkDiagonal_SeqAIJ(mat));
70   PetscFunctionReturn(PETSC_SUCCESS);
71 }
72 
73 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ(Mat A, Mat B, PetscReal fill, Mat C)
74 {
75   Mat_Product        *product = C->product;
76   MatProductAlgorithm alg;
77   PetscBool           flg;
78 
79   PetscFunctionBegin;
80   if (product) {
81     alg = product->alg;
82   } else {
83     alg = "sorted";
84   }
85   /* sorted */
86   PetscCall(PetscStrcmp(alg, "sorted", &flg));
87   if (flg) {
88     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_Sorted(A, B, fill, C));
89     PetscFunctionReturn(PETSC_SUCCESS);
90   }
91 
92   /* scalable */
93   PetscCall(PetscStrcmp(alg, "scalable", &flg));
94   if (flg) {
95     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_Scalable(A, B, fill, C));
96     PetscFunctionReturn(PETSC_SUCCESS);
97   }
98 
99   /* scalable_fast */
100   PetscCall(PetscStrcmp(alg, "scalable_fast", &flg));
101   if (flg) {
102     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_Scalable_fast(A, B, fill, C));
103     PetscFunctionReturn(PETSC_SUCCESS);
104   }
105 
106   /* heap */
107   PetscCall(PetscStrcmp(alg, "heap", &flg));
108   if (flg) {
109     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_Heap(A, B, fill, C));
110     PetscFunctionReturn(PETSC_SUCCESS);
111   }
112 
113   /* btheap */
114   PetscCall(PetscStrcmp(alg, "btheap", &flg));
115   if (flg) {
116     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_BTHeap(A, B, fill, C));
117     PetscFunctionReturn(PETSC_SUCCESS);
118   }
119 
120   /* llcondensed */
121   PetscCall(PetscStrcmp(alg, "llcondensed", &flg));
122   if (flg) {
123     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_LLCondensed(A, B, fill, C));
124     PetscFunctionReturn(PETSC_SUCCESS);
125   }
126 
127   /* rowmerge */
128   PetscCall(PetscStrcmp(alg, "rowmerge", &flg));
129   if (flg) {
130     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_RowMerge(A, B, fill, C));
131     PetscFunctionReturn(PETSC_SUCCESS);
132   }
133 
134 #if defined(PETSC_HAVE_HYPRE)
135   PetscCall(PetscStrcmp(alg, "hypre", &flg));
136   if (flg) {
137     PetscCall(MatMatMultSymbolic_AIJ_AIJ_wHYPRE(A, B, fill, C));
138     PetscFunctionReturn(PETSC_SUCCESS);
139   }
140 #endif
141 
142   SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "Mat Product Algorithm is not supported");
143 }
144 
145 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_LLCondensed(Mat A, Mat B, PetscReal fill, Mat C)
146 {
147   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
148   PetscInt          *ai = a->i, *bi = b->i, *ci, *cj;
149   PetscInt           am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
150   PetscReal          afill;
151   PetscInt           i, j, anzi, brow, bnzj, cnzi, *bj, *aj, *lnk, ndouble = 0, Crmax;
152   PetscHMapI         ta;
153   PetscBT            lnkbt;
154   PetscFreeSpaceList free_space = NULL, current_space = NULL;
155 
156   PetscFunctionBegin;
157   /* Get ci and cj */
158   /* Allocate ci array, arrays for fill computation and */
159   /* free space for accumulating nonzero column info */
160   PetscCall(PetscMalloc1(am + 2, &ci));
161   ci[0] = 0;
162 
163   /* create and initialize a linked list */
164   PetscCall(PetscHMapICreateWithSize(bn, &ta));
165   MatRowMergeMax_SeqAIJ(b, bm, ta);
166   PetscCall(PetscHMapIGetSize(ta, &Crmax));
167   PetscCall(PetscHMapIDestroy(&ta));
168 
169   PetscCall(PetscLLCondensedCreate(Crmax, bn, &lnk, &lnkbt));
170 
171   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
172   PetscCall(PetscFreeSpaceGet(PetscRealIntMultTruncate(fill, PetscIntSumTruncate(ai[am], bi[bm])), &free_space));
173 
174   current_space = free_space;
175 
176   /* Determine ci and cj */
177   for (i = 0; i < am; i++) {
178     anzi = ai[i + 1] - ai[i];
179     aj   = a->j + ai[i];
180     for (j = 0; j < anzi; j++) {
181       brow = aj[j];
182       bnzj = bi[brow + 1] - bi[brow];
183       bj   = b->j + bi[brow];
184       /* add non-zero cols of B into the sorted linked list lnk */
185       PetscCall(PetscLLCondensedAddSorted(bnzj, bj, lnk, lnkbt));
186     }
187     /* add possible missing diagonal entry */
188     if (C->force_diagonals) PetscCall(PetscLLCondensedAddSorted(1, &i, lnk, lnkbt));
189     cnzi = lnk[0];
190 
191     /* If free space is not available, make more free space */
192     /* Double the amount of total space in the list */
193     if (current_space->local_remaining < cnzi) {
194       PetscCall(PetscFreeSpaceGet(PetscIntSumTruncate(cnzi, current_space->total_array_size), &current_space));
195       ndouble++;
196     }
197 
198     /* Copy data into free space, then initialize lnk */
199     PetscCall(PetscLLCondensedClean(bn, cnzi, current_space->array, lnk, lnkbt));
200 
201     current_space->array += cnzi;
202     current_space->local_used += cnzi;
203     current_space->local_remaining -= cnzi;
204 
205     ci[i + 1] = ci[i] + cnzi;
206   }
207 
208   /* Column indices are in the list of free space */
209   /* Allocate space for cj, initialize cj, and */
210   /* destroy list of free space and other temporary array(s) */
211   PetscCall(PetscMalloc1(ci[am] + 1, &cj));
212   PetscCall(PetscFreeSpaceContiguous(&free_space, cj));
213   PetscCall(PetscLLCondensedDestroy(lnk, lnkbt));
214 
215   /* put together the new symbolic matrix */
216   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, NULL, ((PetscObject)A)->type_name, C));
217   PetscCall(MatSetBlockSizesFromMats(C, A, B));
218 
219   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
220   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
221   c          = (Mat_SeqAIJ *)C->data;
222   c->free_a  = PETSC_FALSE;
223   c->free_ij = PETSC_TRUE;
224   c->nonew   = 0;
225 
226   /* fast, needs non-scalable O(bn) array 'abdense' */
227   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted;
228 
229   /* set MatInfo */
230   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
231   if (afill < 1.0) afill = 1.0;
232   C->info.mallocs           = ndouble;
233   C->info.fill_ratio_given  = fill;
234   C->info.fill_ratio_needed = afill;
235 
236 #if defined(PETSC_USE_INFO)
237   if (ci[am]) {
238     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
239     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
240   } else {
241     PetscCall(PetscInfo(C, "Empty matrix product\n"));
242   }
243 #endif
244   PetscFunctionReturn(PETSC_SUCCESS);
245 }
246 
247 PetscErrorCode MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted(Mat A, Mat B, Mat C)
248 {
249   PetscLogDouble     flops = 0.0;
250   Mat_SeqAIJ        *a     = (Mat_SeqAIJ *)A->data;
251   Mat_SeqAIJ        *b     = (Mat_SeqAIJ *)B->data;
252   Mat_SeqAIJ        *c     = (Mat_SeqAIJ *)C->data;
253   PetscInt          *ai = a->i, *aj = a->j, *bi = b->i, *bj = b->j, *bjj, *ci = c->i, *cj = c->j;
254   PetscInt           am = A->rmap->n, cm = C->rmap->n;
255   PetscInt           i, j, k, anzi, bnzi, cnzi, brow;
256   PetscScalar       *ca, valtmp;
257   PetscScalar       *ab_dense;
258   PetscContainer     cab_dense;
259   const PetscScalar *aa, *ba, *baj;
260 
261   PetscFunctionBegin;
262   PetscCall(MatSeqAIJGetArrayRead(A, &aa));
263   PetscCall(MatSeqAIJGetArrayRead(B, &ba));
264   if (!c->a) { /* first call of MatMatMultNumeric_SeqAIJ_SeqAIJ, allocate ca and matmult_abdense */
265     PetscCall(PetscMalloc1(ci[cm] + 1, &ca));
266     c->a      = ca;
267     c->free_a = PETSC_TRUE;
268   } else ca = c->a;
269 
270   /* TODO this should be done in the symbolic phase */
271   /* However, this function is so heavily used (sometimes in an hidden way through multnumeric function pointers
272      that is hard to eradicate) */
273   PetscCall(PetscObjectQuery((PetscObject)C, "__PETSc__ab_dense", (PetscObject *)&cab_dense));
274   if (!cab_dense) {
275     PetscCall(PetscMalloc1(B->cmap->N, &ab_dense));
276     PetscCall(PetscObjectContainerCompose((PetscObject)C, "__PETSc__ab_dense", ab_dense, PetscCtxDestroyDefault));
277   } else PetscCall(PetscContainerGetPointer(cab_dense, (void **)&ab_dense));
278   PetscCall(PetscArrayzero(ab_dense, B->cmap->N));
279 
280   /* clean old values in C */
281   PetscCall(PetscArrayzero(ca, ci[cm]));
282   /* Traverse A row-wise. */
283   /* Build the ith row in C by summing over nonzero columns in A, */
284   /* the rows of B corresponding to nonzeros of A. */
285   for (i = 0; i < am; i++) {
286     anzi = ai[i + 1] - ai[i];
287     for (j = 0; j < anzi; j++) {
288       brow = aj[j];
289       bnzi = bi[brow + 1] - bi[brow];
290       bjj  = PetscSafePointerPlusOffset(bj, bi[brow]);
291       baj  = PetscSafePointerPlusOffset(ba, bi[brow]);
292       /* perform dense axpy */
293       valtmp = aa[j];
294       for (k = 0; k < bnzi; k++) ab_dense[bjj[k]] += valtmp * baj[k];
295       flops += 2 * bnzi;
296     }
297     aj = PetscSafePointerPlusOffset(aj, anzi);
298     aa = PetscSafePointerPlusOffset(aa, anzi);
299 
300     cnzi = ci[i + 1] - ci[i];
301     for (k = 0; k < cnzi; k++) {
302       ca[k] += ab_dense[cj[k]];
303       ab_dense[cj[k]] = 0.0; /* zero ab_dense */
304     }
305     flops += cnzi;
306     cj = PetscSafePointerPlusOffset(cj, cnzi);
307     ca += cnzi;
308   }
309 #if defined(PETSC_HAVE_DEVICE)
310   if (C->offloadmask != PETSC_OFFLOAD_UNALLOCATED) C->offloadmask = PETSC_OFFLOAD_CPU;
311 #endif
312   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
313   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
314   PetscCall(PetscLogFlops(flops));
315   PetscCall(MatSeqAIJRestoreArrayRead(A, &aa));
316   PetscCall(MatSeqAIJRestoreArrayRead(B, &ba));
317   PetscFunctionReturn(PETSC_SUCCESS);
318 }
319 
320 PetscErrorCode MatMatMultNumeric_SeqAIJ_SeqAIJ_Scalable(Mat A, Mat B, Mat C)
321 {
322   PetscLogDouble     flops = 0.0;
323   Mat_SeqAIJ        *a     = (Mat_SeqAIJ *)A->data;
324   Mat_SeqAIJ        *b     = (Mat_SeqAIJ *)B->data;
325   Mat_SeqAIJ        *c     = (Mat_SeqAIJ *)C->data;
326   PetscInt          *ai = a->i, *aj = a->j, *bi = b->i, *bj = b->j, *bjj, *ci = c->i, *cj = c->j;
327   PetscInt           am = A->rmap->N, cm = C->rmap->N;
328   PetscInt           i, j, k, anzi, bnzi, cnzi, brow;
329   PetscScalar       *ca = c->a, valtmp;
330   const PetscScalar *aa, *ba, *baj;
331   PetscInt           nextb;
332 
333   PetscFunctionBegin;
334   PetscCall(MatSeqAIJGetArrayRead(A, &aa));
335   PetscCall(MatSeqAIJGetArrayRead(B, &ba));
336   if (!ca) { /* first call of MatMatMultNumeric_SeqAIJ_SeqAIJ, allocate ca and matmult_abdense */
337     PetscCall(PetscMalloc1(ci[cm] + 1, &ca));
338     c->a      = ca;
339     c->free_a = PETSC_TRUE;
340   }
341 
342   /* clean old values in C */
343   PetscCall(PetscArrayzero(ca, ci[cm]));
344   /* Traverse A row-wise. */
345   /* Build the ith row in C by summing over nonzero columns in A, */
346   /* the rows of B corresponding to nonzeros of A. */
347   for (i = 0; i < am; i++) {
348     anzi = ai[i + 1] - ai[i];
349     cnzi = ci[i + 1] - ci[i];
350     for (j = 0; j < anzi; j++) {
351       brow = aj[j];
352       bnzi = bi[brow + 1] - bi[brow];
353       bjj  = bj + bi[brow];
354       baj  = ba + bi[brow];
355       /* perform sparse axpy */
356       valtmp = aa[j];
357       nextb  = 0;
358       for (k = 0; nextb < bnzi; k++) {
359         if (cj[k] == bjj[nextb]) { /* ccol == bcol */
360           ca[k] += valtmp * baj[nextb++];
361         }
362       }
363       flops += 2 * bnzi;
364     }
365     aj += anzi;
366     aa += anzi;
367     cj += cnzi;
368     ca += cnzi;
369   }
370 #if defined(PETSC_HAVE_DEVICE)
371   if (C->offloadmask != PETSC_OFFLOAD_UNALLOCATED) C->offloadmask = PETSC_OFFLOAD_CPU;
372 #endif
373   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
374   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
375   PetscCall(PetscLogFlops(flops));
376   PetscCall(MatSeqAIJRestoreArrayRead(A, &aa));
377   PetscCall(MatSeqAIJRestoreArrayRead(B, &ba));
378   PetscFunctionReturn(PETSC_SUCCESS);
379 }
380 
381 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_Scalable_fast(Mat A, Mat B, PetscReal fill, Mat C)
382 {
383   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
384   PetscInt          *ai = a->i, *bi = b->i, *ci, *cj;
385   PetscInt           am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
386   MatScalar         *ca;
387   PetscReal          afill;
388   PetscInt           i, j, anzi, brow, bnzj, cnzi, *bj, *aj, *lnk, ndouble = 0, Crmax;
389   PetscHMapI         ta;
390   PetscFreeSpaceList free_space = NULL, current_space = NULL;
391 
392   PetscFunctionBegin;
393   /* Get ci and cj - same as MatMatMultSymbolic_SeqAIJ_SeqAIJ except using PetscLLxxx_fast() */
394   /* Allocate arrays for fill computation and free space for accumulating nonzero column */
395   PetscCall(PetscMalloc1(am + 2, &ci));
396   ci[0] = 0;
397 
398   /* create and initialize a linked list */
399   PetscCall(PetscHMapICreateWithSize(bn, &ta));
400   MatRowMergeMax_SeqAIJ(b, bm, ta);
401   PetscCall(PetscHMapIGetSize(ta, &Crmax));
402   PetscCall(PetscHMapIDestroy(&ta));
403 
404   PetscCall(PetscLLCondensedCreate_fast(Crmax, &lnk));
405 
406   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
407   PetscCall(PetscFreeSpaceGet(PetscRealIntMultTruncate(fill, PetscIntSumTruncate(ai[am], bi[bm])), &free_space));
408   current_space = free_space;
409 
410   /* Determine ci and cj */
411   for (i = 0; i < am; i++) {
412     anzi = ai[i + 1] - ai[i];
413     aj   = a->j + ai[i];
414     for (j = 0; j < anzi; j++) {
415       brow = aj[j];
416       bnzj = bi[brow + 1] - bi[brow];
417       bj   = b->j + bi[brow];
418       /* add non-zero cols of B into the sorted linked list lnk */
419       PetscCall(PetscLLCondensedAddSorted_fast(bnzj, bj, lnk));
420     }
421     /* add possible missing diagonal entry */
422     if (C->force_diagonals) PetscCall(PetscLLCondensedAddSorted_fast(1, &i, lnk));
423     cnzi = lnk[1];
424 
425     /* If free space is not available, make more free space */
426     /* Double the amount of total space in the list */
427     if (current_space->local_remaining < cnzi) {
428       PetscCall(PetscFreeSpaceGet(PetscIntSumTruncate(cnzi, current_space->total_array_size), &current_space));
429       ndouble++;
430     }
431 
432     /* Copy data into free space, then initialize lnk */
433     PetscCall(PetscLLCondensedClean_fast(cnzi, current_space->array, lnk));
434 
435     current_space->array += cnzi;
436     current_space->local_used += cnzi;
437     current_space->local_remaining -= cnzi;
438 
439     ci[i + 1] = ci[i] + cnzi;
440   }
441 
442   /* Column indices are in the list of free space */
443   /* Allocate space for cj, initialize cj, and */
444   /* destroy list of free space and other temporary array(s) */
445   PetscCall(PetscMalloc1(ci[am] + 1, &cj));
446   PetscCall(PetscFreeSpaceContiguous(&free_space, cj));
447   PetscCall(PetscLLCondensedDestroy_fast(lnk));
448 
449   /* Allocate space for ca */
450   PetscCall(PetscCalloc1(ci[am] + 1, &ca));
451 
452   /* put together the new symbolic matrix */
453   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, ca, ((PetscObject)A)->type_name, C));
454   PetscCall(MatSetBlockSizesFromMats(C, A, B));
455 
456   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
457   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
458   c          = (Mat_SeqAIJ *)C->data;
459   c->free_a  = PETSC_TRUE;
460   c->free_ij = PETSC_TRUE;
461   c->nonew   = 0;
462 
463   /* slower, less memory */
464   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Scalable;
465 
466   /* set MatInfo */
467   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
468   if (afill < 1.0) afill = 1.0;
469   C->info.mallocs           = ndouble;
470   C->info.fill_ratio_given  = fill;
471   C->info.fill_ratio_needed = afill;
472 
473 #if defined(PETSC_USE_INFO)
474   if (ci[am]) {
475     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
476     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
477   } else {
478     PetscCall(PetscInfo(C, "Empty matrix product\n"));
479   }
480 #endif
481   PetscFunctionReturn(PETSC_SUCCESS);
482 }
483 
484 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_Scalable(Mat A, Mat B, PetscReal fill, Mat C)
485 {
486   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
487   PetscInt          *ai = a->i, *bi = b->i, *ci, *cj;
488   PetscInt           am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
489   MatScalar         *ca;
490   PetscReal          afill;
491   PetscInt           i, j, anzi, brow, bnzj, cnzi, *bj, *aj, *lnk, ndouble = 0, Crmax;
492   PetscHMapI         ta;
493   PetscFreeSpaceList free_space = NULL, current_space = NULL;
494 
495   PetscFunctionBegin;
496   /* Get ci and cj - same as MatMatMultSymbolic_SeqAIJ_SeqAIJ except using PetscLLxxx_Scalalbe() */
497   /* Allocate arrays for fill computation and free space for accumulating nonzero column */
498   PetscCall(PetscMalloc1(am + 2, &ci));
499   ci[0] = 0;
500 
501   /* create and initialize a linked list */
502   PetscCall(PetscHMapICreateWithSize(bn, &ta));
503   MatRowMergeMax_SeqAIJ(b, bm, ta);
504   PetscCall(PetscHMapIGetSize(ta, &Crmax));
505   PetscCall(PetscHMapIDestroy(&ta));
506   PetscCall(PetscLLCondensedCreate_Scalable(Crmax, &lnk));
507 
508   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
509   PetscCall(PetscFreeSpaceGet(PetscRealIntMultTruncate(fill, PetscIntSumTruncate(ai[am], bi[bm])), &free_space));
510   current_space = free_space;
511 
512   /* Determine ci and cj */
513   for (i = 0; i < am; i++) {
514     anzi = ai[i + 1] - ai[i];
515     aj   = a->j + ai[i];
516     for (j = 0; j < anzi; j++) {
517       brow = aj[j];
518       bnzj = bi[brow + 1] - bi[brow];
519       bj   = b->j + bi[brow];
520       /* add non-zero cols of B into the sorted linked list lnk */
521       PetscCall(PetscLLCondensedAddSorted_Scalable(bnzj, bj, lnk));
522     }
523     /* add possible missing diagonal entry */
524     if (C->force_diagonals) PetscCall(PetscLLCondensedAddSorted_Scalable(1, &i, lnk));
525 
526     cnzi = lnk[0];
527 
528     /* If free space is not available, make more free space */
529     /* Double the amount of total space in the list */
530     if (current_space->local_remaining < cnzi) {
531       PetscCall(PetscFreeSpaceGet(PetscIntSumTruncate(cnzi, current_space->total_array_size), &current_space));
532       ndouble++;
533     }
534 
535     /* Copy data into free space, then initialize lnk */
536     PetscCall(PetscLLCondensedClean_Scalable(cnzi, current_space->array, lnk));
537 
538     current_space->array += cnzi;
539     current_space->local_used += cnzi;
540     current_space->local_remaining -= cnzi;
541 
542     ci[i + 1] = ci[i] + cnzi;
543   }
544 
545   /* Column indices are in the list of free space */
546   /* Allocate space for cj, initialize cj, and */
547   /* destroy list of free space and other temporary array(s) */
548   PetscCall(PetscMalloc1(ci[am] + 1, &cj));
549   PetscCall(PetscFreeSpaceContiguous(&free_space, cj));
550   PetscCall(PetscLLCondensedDestroy_Scalable(lnk));
551 
552   /* Allocate space for ca */
553   PetscCall(PetscCalloc1(ci[am] + 1, &ca));
554 
555   /* put together the new symbolic matrix */
556   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, ca, ((PetscObject)A)->type_name, C));
557   PetscCall(MatSetBlockSizesFromMats(C, A, B));
558 
559   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
560   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
561   c          = (Mat_SeqAIJ *)C->data;
562   c->free_a  = PETSC_TRUE;
563   c->free_ij = PETSC_TRUE;
564   c->nonew   = 0;
565 
566   /* slower, less memory */
567   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Scalable;
568 
569   /* set MatInfo */
570   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
571   if (afill < 1.0) afill = 1.0;
572   C->info.mallocs           = ndouble;
573   C->info.fill_ratio_given  = fill;
574   C->info.fill_ratio_needed = afill;
575 
576 #if defined(PETSC_USE_INFO)
577   if (ci[am]) {
578     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
579     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
580   } else {
581     PetscCall(PetscInfo(C, "Empty matrix product\n"));
582   }
583 #endif
584   PetscFunctionReturn(PETSC_SUCCESS);
585 }
586 
587 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_Heap(Mat A, Mat B, PetscReal fill, Mat C)
588 {
589   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
590   const PetscInt    *ai = a->i, *bi = b->i, *aj = a->j, *bj = b->j;
591   PetscInt          *ci, *cj, *bb;
592   PetscInt           am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
593   PetscReal          afill;
594   PetscInt           i, j, col, ndouble = 0;
595   PetscFreeSpaceList free_space = NULL, current_space = NULL;
596   PetscHeap          h;
597 
598   PetscFunctionBegin;
599   /* Get ci and cj - by merging sorted rows using a heap */
600   /* Allocate arrays for fill computation and free space for accumulating nonzero column */
601   PetscCall(PetscMalloc1(am + 2, &ci));
602   ci[0] = 0;
603 
604   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
605   PetscCall(PetscFreeSpaceGet(PetscRealIntMultTruncate(fill, PetscIntSumTruncate(ai[am], bi[bm])), &free_space));
606   current_space = free_space;
607 
608   PetscCall(PetscHeapCreate(a->rmax, &h));
609   PetscCall(PetscMalloc1(a->rmax, &bb));
610 
611   /* Determine ci and cj */
612   for (i = 0; i < am; i++) {
613     const PetscInt  anzi = ai[i + 1] - ai[i]; /* number of nonzeros in this row of A, this is the number of rows of B that we merge */
614     const PetscInt *acol = aj + ai[i];        /* column indices of nonzero entries in this row */
615     ci[i + 1]            = ci[i];
616     /* Populate the min heap */
617     for (j = 0; j < anzi; j++) {
618       bb[j] = bi[acol[j]];           /* bb points at the start of the row */
619       if (bb[j] < bi[acol[j] + 1]) { /* Add if row is nonempty */
620         PetscCall(PetscHeapAdd(h, j, bj[bb[j]++]));
621       }
622     }
623     /* Pick off the min element, adding it to free space */
624     PetscCall(PetscHeapPop(h, &j, &col));
625     while (j >= 0) {
626       if (current_space->local_remaining < 1) { /* double the size, but don't exceed 16 MiB */
627         PetscCall(PetscFreeSpaceGet(PetscMin(PetscIntMultTruncate(2, current_space->total_array_size), 16 << 20), &current_space));
628         ndouble++;
629       }
630       *(current_space->array++) = col;
631       current_space->local_used++;
632       current_space->local_remaining--;
633       ci[i + 1]++;
634 
635       /* stash if anything else remains in this row of B */
636       if (bb[j] < bi[acol[j] + 1]) PetscCall(PetscHeapStash(h, j, bj[bb[j]++]));
637       while (1) { /* pop and stash any other rows of B that also had an entry in this column */
638         PetscInt j2, col2;
639         PetscCall(PetscHeapPeek(h, &j2, &col2));
640         if (col2 != col) break;
641         PetscCall(PetscHeapPop(h, &j2, &col2));
642         if (bb[j2] < bi[acol[j2] + 1]) PetscCall(PetscHeapStash(h, j2, bj[bb[j2]++]));
643       }
644       /* Put any stashed elements back into the min heap */
645       PetscCall(PetscHeapUnstash(h));
646       PetscCall(PetscHeapPop(h, &j, &col));
647     }
648   }
649   PetscCall(PetscFree(bb));
650   PetscCall(PetscHeapDestroy(&h));
651 
652   /* Column indices are in the list of free space */
653   /* Allocate space for cj, initialize cj, and */
654   /* destroy list of free space and other temporary array(s) */
655   PetscCall(PetscMalloc1(ci[am], &cj));
656   PetscCall(PetscFreeSpaceContiguous(&free_space, cj));
657 
658   /* put together the new symbolic matrix */
659   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, NULL, ((PetscObject)A)->type_name, C));
660   PetscCall(MatSetBlockSizesFromMats(C, A, B));
661 
662   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
663   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
664   c          = (Mat_SeqAIJ *)C->data;
665   c->free_a  = PETSC_TRUE;
666   c->free_ij = PETSC_TRUE;
667   c->nonew   = 0;
668 
669   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted;
670 
671   /* set MatInfo */
672   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
673   if (afill < 1.0) afill = 1.0;
674   C->info.mallocs           = ndouble;
675   C->info.fill_ratio_given  = fill;
676   C->info.fill_ratio_needed = afill;
677 
678 #if defined(PETSC_USE_INFO)
679   if (ci[am]) {
680     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
681     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
682   } else {
683     PetscCall(PetscInfo(C, "Empty matrix product\n"));
684   }
685 #endif
686   PetscFunctionReturn(PETSC_SUCCESS);
687 }
688 
689 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_BTHeap(Mat A, Mat B, PetscReal fill, Mat C)
690 {
691   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
692   const PetscInt    *ai = a->i, *bi = b->i, *aj = a->j, *bj = b->j;
693   PetscInt          *ci, *cj, *bb;
694   PetscInt           am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
695   PetscReal          afill;
696   PetscInt           i, j, col, ndouble = 0;
697   PetscFreeSpaceList free_space = NULL, current_space = NULL;
698   PetscHeap          h;
699   PetscBT            bt;
700 
701   PetscFunctionBegin;
702   /* Get ci and cj - using a heap for the sorted rows, but use BT so that each index is only added once */
703   /* Allocate arrays for fill computation and free space for accumulating nonzero column */
704   PetscCall(PetscMalloc1(am + 2, &ci));
705   ci[0] = 0;
706 
707   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
708   PetscCall(PetscFreeSpaceGet(PetscRealIntMultTruncate(fill, PetscIntSumTruncate(ai[am], bi[bm])), &free_space));
709 
710   current_space = free_space;
711 
712   PetscCall(PetscHeapCreate(a->rmax, &h));
713   PetscCall(PetscMalloc1(a->rmax, &bb));
714   PetscCall(PetscBTCreate(bn, &bt));
715 
716   /* Determine ci and cj */
717   for (i = 0; i < am; i++) {
718     const PetscInt  anzi = ai[i + 1] - ai[i];    /* number of nonzeros in this row of A, this is the number of rows of B that we merge */
719     const PetscInt *acol = aj + ai[i];           /* column indices of nonzero entries in this row */
720     const PetscInt *fptr = current_space->array; /* Save beginning of the row so we can clear the BT later */
721     ci[i + 1]            = ci[i];
722     /* Populate the min heap */
723     for (j = 0; j < anzi; j++) {
724       PetscInt brow = acol[j];
725       for (bb[j] = bi[brow]; bb[j] < bi[brow + 1]; bb[j]++) {
726         PetscInt bcol = bj[bb[j]];
727         if (!PetscBTLookupSet(bt, bcol)) { /* new entry */
728           PetscCall(PetscHeapAdd(h, j, bcol));
729           bb[j]++;
730           break;
731         }
732       }
733     }
734     /* Pick off the min element, adding it to free space */
735     PetscCall(PetscHeapPop(h, &j, &col));
736     while (j >= 0) {
737       if (current_space->local_remaining < 1) { /* double the size, but don't exceed 16 MiB */
738         fptr = NULL;                            /* need PetscBTMemzero */
739         PetscCall(PetscFreeSpaceGet(PetscMin(PetscIntMultTruncate(2, current_space->total_array_size), 16 << 20), &current_space));
740         ndouble++;
741       }
742       *(current_space->array++) = col;
743       current_space->local_used++;
744       current_space->local_remaining--;
745       ci[i + 1]++;
746 
747       /* stash if anything else remains in this row of B */
748       for (; bb[j] < bi[acol[j] + 1]; bb[j]++) {
749         PetscInt bcol = bj[bb[j]];
750         if (!PetscBTLookupSet(bt, bcol)) { /* new entry */
751           PetscCall(PetscHeapAdd(h, j, bcol));
752           bb[j]++;
753           break;
754         }
755       }
756       PetscCall(PetscHeapPop(h, &j, &col));
757     }
758     if (fptr) { /* Clear the bits for this row */
759       for (; fptr < current_space->array; fptr++) PetscCall(PetscBTClear(bt, *fptr));
760     } else { /* We reallocated so we don't remember (easily) how to clear only the bits we changed */
761       PetscCall(PetscBTMemzero(bn, bt));
762     }
763   }
764   PetscCall(PetscFree(bb));
765   PetscCall(PetscHeapDestroy(&h));
766   PetscCall(PetscBTDestroy(&bt));
767 
768   /* Column indices are in the list of free space */
769   /* Allocate space for cj, initialize cj, and */
770   /* destroy list of free space and other temporary array(s) */
771   PetscCall(PetscMalloc1(ci[am], &cj));
772   PetscCall(PetscFreeSpaceContiguous(&free_space, cj));
773 
774   /* put together the new symbolic matrix */
775   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, NULL, ((PetscObject)A)->type_name, C));
776   PetscCall(MatSetBlockSizesFromMats(C, A, B));
777 
778   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
779   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
780   c          = (Mat_SeqAIJ *)C->data;
781   c->free_a  = PETSC_TRUE;
782   c->free_ij = PETSC_TRUE;
783   c->nonew   = 0;
784 
785   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted;
786 
787   /* set MatInfo */
788   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
789   if (afill < 1.0) afill = 1.0;
790   C->info.mallocs           = ndouble;
791   C->info.fill_ratio_given  = fill;
792   C->info.fill_ratio_needed = afill;
793 
794 #if defined(PETSC_USE_INFO)
795   if (ci[am]) {
796     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
797     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
798   } else {
799     PetscCall(PetscInfo(C, "Empty matrix product\n"));
800   }
801 #endif
802   PetscFunctionReturn(PETSC_SUCCESS);
803 }
804 
805 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_RowMerge(Mat A, Mat B, PetscReal fill, Mat C)
806 {
807   Mat_SeqAIJ     *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
808   const PetscInt *ai = a->i, *bi = b->i, *aj = a->j, *bj = b->j, *inputi, *inputj, *inputcol, *inputcol_L1;
809   PetscInt       *ci, *cj, *outputj, worki_L1[9], worki_L2[9];
810   PetscInt        c_maxmem, a_maxrownnz = 0, a_rownnz;
811   const PetscInt  workcol[8] = {0, 1, 2, 3, 4, 5, 6, 7};
812   const PetscInt  am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
813   const PetscInt *brow_ptr[8], *brow_end[8];
814   PetscInt        window[8];
815   PetscInt        window_min, old_window_min, ci_nnz, outputi_nnz = 0, L1_nrows, L2_nrows;
816   PetscInt        i, k, ndouble = 0, L1_rowsleft, rowsleft;
817   PetscReal       afill;
818   PetscInt       *workj_L1, *workj_L2, *workj_L3;
819   PetscInt        L1_nnz, L2_nnz;
820 
821   /* Step 1: Get upper bound on memory required for allocation.
822              Because of the way virtual memory works,
823              only the memory pages that are actually needed will be physically allocated. */
824   PetscFunctionBegin;
825   PetscCall(PetscMalloc1(am + 1, &ci));
826   for (i = 0; i < am; i++) {
827     const PetscInt  anzi = ai[i + 1] - ai[i]; /* number of nonzeros in this row of A, this is the number of rows of B that we merge */
828     const PetscInt *acol = aj + ai[i];        /* column indices of nonzero entries in this row */
829     a_rownnz             = 0;
830     for (k = 0; k < anzi; ++k) {
831       a_rownnz += bi[acol[k] + 1] - bi[acol[k]];
832       if (a_rownnz > bn) {
833         a_rownnz = bn;
834         break;
835       }
836     }
837     a_maxrownnz = PetscMax(a_maxrownnz, a_rownnz);
838   }
839   /* temporary work areas for merging rows */
840   PetscCall(PetscMalloc1(a_maxrownnz * 8, &workj_L1));
841   PetscCall(PetscMalloc1(a_maxrownnz * 8, &workj_L2));
842   PetscCall(PetscMalloc1(a_maxrownnz, &workj_L3));
843 
844   /* This should be enough for almost all matrices. If not, memory is reallocated later. */
845   c_maxmem = 8 * (ai[am] + bi[bm]);
846   /* Step 2: Populate pattern for C */
847   PetscCall(PetscMalloc1(c_maxmem, &cj));
848 
849   ci_nnz      = 0;
850   ci[0]       = 0;
851   worki_L1[0] = 0;
852   worki_L2[0] = 0;
853   for (i = 0; i < am; i++) {
854     const PetscInt  anzi = ai[i + 1] - ai[i]; /* number of nonzeros in this row of A, this is the number of rows of B that we merge */
855     const PetscInt *acol = aj + ai[i];        /* column indices of nonzero entries in this row */
856     rowsleft             = anzi;
857     inputcol_L1          = acol;
858     L2_nnz               = 0;
859     L2_nrows             = 1; /* Number of rows to be merged on Level 3. output of L3 already exists -> initial value 1   */
860     worki_L2[1]          = 0;
861     outputi_nnz          = 0;
862 
863     /* If the number of indices in C so far + the max number of columns in the next row > c_maxmem  -> allocate more memory */
864     while (ci_nnz + a_maxrownnz > c_maxmem) {
865       c_maxmem *= 2;
866       ndouble++;
867       PetscCall(PetscRealloc(sizeof(PetscInt) * c_maxmem, &cj));
868     }
869 
870     while (rowsleft) {
871       L1_rowsleft = PetscMin(64, rowsleft); /* In the inner loop max 64 rows of B can be merged */
872       L1_nrows    = 0;
873       L1_nnz      = 0;
874       inputcol    = inputcol_L1;
875       inputi      = bi;
876       inputj      = bj;
877 
878       /* The following macro is used to specialize for small rows in A.
879          This helps with compiler unrolling, improving performance substantially.
880           Input:  inputj   inputi  inputcol  bn
881           Output: outputj  outputi_nnz                       */
882 #define MatMatMultSymbolic_RowMergeMacro(ANNZ) \
883   do { \
884     window_min  = bn; \
885     outputi_nnz = 0; \
886     for (k = 0; k < ANNZ; ++k) { \
887       brow_ptr[k] = inputj + inputi[inputcol[k]]; \
888       brow_end[k] = inputj + inputi[inputcol[k] + 1]; \
889       window[k]   = (brow_ptr[k] != brow_end[k]) ? *brow_ptr[k] : bn; \
890       window_min  = PetscMin(window[k], window_min); \
891     } \
892     while (window_min < bn) { \
893       outputj[outputi_nnz++] = window_min; \
894       /* advance front and compute new minimum */ \
895       old_window_min = window_min; \
896       window_min     = bn; \
897       for (k = 0; k < ANNZ; ++k) { \
898         if (window[k] == old_window_min) { \
899           brow_ptr[k]++; \
900           window[k] = (brow_ptr[k] != brow_end[k]) ? *brow_ptr[k] : bn; \
901         } \
902         window_min = PetscMin(window[k], window_min); \
903       } \
904     } \
905   } while (0)
906 
907       /************** L E V E L  1 ***************/
908       /* Merge up to 8 rows of B to L1 work array*/
909       while (L1_rowsleft) {
910         outputi_nnz = 0;
911         if (anzi > 8) outputj = workj_L1 + L1_nnz; /* Level 1 rowmerge*/
912         else outputj = cj + ci_nnz;                /* Merge directly to C */
913 
914         switch (L1_rowsleft) {
915         case 1:
916           brow_ptr[0] = inputj + inputi[inputcol[0]];
917           brow_end[0] = inputj + inputi[inputcol[0] + 1];
918           for (; brow_ptr[0] != brow_end[0]; ++brow_ptr[0]) outputj[outputi_nnz++] = *brow_ptr[0]; /* copy row in b over */
919           inputcol += L1_rowsleft;
920           rowsleft -= L1_rowsleft;
921           L1_rowsleft = 0;
922           break;
923         case 2:
924           MatMatMultSymbolic_RowMergeMacro(2);
925           inputcol += L1_rowsleft;
926           rowsleft -= L1_rowsleft;
927           L1_rowsleft = 0;
928           break;
929         case 3:
930           MatMatMultSymbolic_RowMergeMacro(3);
931           inputcol += L1_rowsleft;
932           rowsleft -= L1_rowsleft;
933           L1_rowsleft = 0;
934           break;
935         case 4:
936           MatMatMultSymbolic_RowMergeMacro(4);
937           inputcol += L1_rowsleft;
938           rowsleft -= L1_rowsleft;
939           L1_rowsleft = 0;
940           break;
941         case 5:
942           MatMatMultSymbolic_RowMergeMacro(5);
943           inputcol += L1_rowsleft;
944           rowsleft -= L1_rowsleft;
945           L1_rowsleft = 0;
946           break;
947         case 6:
948           MatMatMultSymbolic_RowMergeMacro(6);
949           inputcol += L1_rowsleft;
950           rowsleft -= L1_rowsleft;
951           L1_rowsleft = 0;
952           break;
953         case 7:
954           MatMatMultSymbolic_RowMergeMacro(7);
955           inputcol += L1_rowsleft;
956           rowsleft -= L1_rowsleft;
957           L1_rowsleft = 0;
958           break;
959         default:
960           MatMatMultSymbolic_RowMergeMacro(8);
961           inputcol += 8;
962           rowsleft -= 8;
963           L1_rowsleft -= 8;
964           break;
965         }
966         inputcol_L1 = inputcol;
967         L1_nnz += outputi_nnz;
968         worki_L1[++L1_nrows] = L1_nnz;
969       }
970 
971       /********************** L E V E L  2 ************************/
972       /* Merge from L1 work array to either C or to L2 work array */
973       if (anzi > 8) {
974         inputi      = worki_L1;
975         inputj      = workj_L1;
976         inputcol    = workcol;
977         outputi_nnz = 0;
978 
979         if (anzi <= 64) outputj = cj + ci_nnz; /* Merge from L1 work array to C */
980         else outputj = workj_L2 + L2_nnz;      /* Merge from L1 work array to L2 work array */
981 
982         switch (L1_nrows) {
983         case 1:
984           brow_ptr[0] = inputj + inputi[inputcol[0]];
985           brow_end[0] = inputj + inputi[inputcol[0] + 1];
986           for (; brow_ptr[0] != brow_end[0]; ++brow_ptr[0]) outputj[outputi_nnz++] = *brow_ptr[0]; /* copy row in b over */
987           break;
988         case 2:
989           MatMatMultSymbolic_RowMergeMacro(2);
990           break;
991         case 3:
992           MatMatMultSymbolic_RowMergeMacro(3);
993           break;
994         case 4:
995           MatMatMultSymbolic_RowMergeMacro(4);
996           break;
997         case 5:
998           MatMatMultSymbolic_RowMergeMacro(5);
999           break;
1000         case 6:
1001           MatMatMultSymbolic_RowMergeMacro(6);
1002           break;
1003         case 7:
1004           MatMatMultSymbolic_RowMergeMacro(7);
1005           break;
1006         case 8:
1007           MatMatMultSymbolic_RowMergeMacro(8);
1008           break;
1009         default:
1010           SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "MatMatMult logic error: Not merging 1-8 rows from L1 work array!");
1011         }
1012         L2_nnz += outputi_nnz;
1013         worki_L2[++L2_nrows] = L2_nnz;
1014 
1015         /************************ L E V E L  3 **********************/
1016         /* Merge from L2 work array to either C or to L2 work array */
1017         if (anzi > 64 && (L2_nrows == 8 || rowsleft == 0)) {
1018           inputi      = worki_L2;
1019           inputj      = workj_L2;
1020           inputcol    = workcol;
1021           outputi_nnz = 0;
1022           if (rowsleft) outputj = workj_L3;
1023           else outputj = cj + ci_nnz;
1024           switch (L2_nrows) {
1025           case 1:
1026             brow_ptr[0] = inputj + inputi[inputcol[0]];
1027             brow_end[0] = inputj + inputi[inputcol[0] + 1];
1028             for (; brow_ptr[0] != brow_end[0]; ++brow_ptr[0]) outputj[outputi_nnz++] = *brow_ptr[0]; /* copy row in b over */
1029             break;
1030           case 2:
1031             MatMatMultSymbolic_RowMergeMacro(2);
1032             break;
1033           case 3:
1034             MatMatMultSymbolic_RowMergeMacro(3);
1035             break;
1036           case 4:
1037             MatMatMultSymbolic_RowMergeMacro(4);
1038             break;
1039           case 5:
1040             MatMatMultSymbolic_RowMergeMacro(5);
1041             break;
1042           case 6:
1043             MatMatMultSymbolic_RowMergeMacro(6);
1044             break;
1045           case 7:
1046             MatMatMultSymbolic_RowMergeMacro(7);
1047             break;
1048           case 8:
1049             MatMatMultSymbolic_RowMergeMacro(8);
1050             break;
1051           default:
1052             SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "MatMatMult logic error: Not merging 1-8 rows from L2 work array!");
1053           }
1054           L2_nrows    = 1;
1055           L2_nnz      = outputi_nnz;
1056           worki_L2[1] = outputi_nnz;
1057           /* Copy to workj_L2 */
1058           if (rowsleft) {
1059             for (k = 0; k < outputi_nnz; ++k) workj_L2[k] = outputj[k];
1060           }
1061         }
1062       }
1063     } /* while (rowsleft) */
1064 #undef MatMatMultSymbolic_RowMergeMacro
1065 
1066     /* terminate current row */
1067     ci_nnz += outputi_nnz;
1068     ci[i + 1] = ci_nnz;
1069   }
1070 
1071   /* Step 3: Create the new symbolic matrix */
1072   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, NULL, ((PetscObject)A)->type_name, C));
1073   PetscCall(MatSetBlockSizesFromMats(C, A, B));
1074 
1075   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
1076   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
1077   c          = (Mat_SeqAIJ *)C->data;
1078   c->free_a  = PETSC_TRUE;
1079   c->free_ij = PETSC_TRUE;
1080   c->nonew   = 0;
1081 
1082   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted;
1083 
1084   /* set MatInfo */
1085   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
1086   if (afill < 1.0) afill = 1.0;
1087   C->info.mallocs           = ndouble;
1088   C->info.fill_ratio_given  = fill;
1089   C->info.fill_ratio_needed = afill;
1090 
1091 #if defined(PETSC_USE_INFO)
1092   if (ci[am]) {
1093     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
1094     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
1095   } else {
1096     PetscCall(PetscInfo(C, "Empty matrix product\n"));
1097   }
1098 #endif
1099 
1100   /* Step 4: Free temporary work areas */
1101   PetscCall(PetscFree(workj_L1));
1102   PetscCall(PetscFree(workj_L2));
1103   PetscCall(PetscFree(workj_L3));
1104   PetscFunctionReturn(PETSC_SUCCESS);
1105 }
1106 
1107 /* concatenate unique entries and then sort */
1108 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_Sorted(Mat A, Mat B, PetscReal fill, Mat C)
1109 {
1110   Mat_SeqAIJ     *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
1111   const PetscInt *ai = a->i, *bi = b->i, *aj = a->j, *bj = b->j;
1112   PetscInt       *ci, *cj, bcol;
1113   PetscInt        am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
1114   PetscReal       afill;
1115   PetscInt        i, j, ndouble = 0;
1116   PetscSegBuffer  seg, segrow;
1117   char           *seen;
1118 
1119   PetscFunctionBegin;
1120   PetscCall(PetscMalloc1(am + 1, &ci));
1121   ci[0] = 0;
1122 
1123   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
1124   PetscCall(PetscSegBufferCreate(sizeof(PetscInt), (PetscInt)(fill * (ai[am] + bi[bm])), &seg));
1125   PetscCall(PetscSegBufferCreate(sizeof(PetscInt), 100, &segrow));
1126   PetscCall(PetscCalloc1(bn, &seen));
1127 
1128   /* Determine ci and cj */
1129   for (i = 0; i < am; i++) {
1130     const PetscInt  anzi = ai[i + 1] - ai[i];                     /* number of nonzeros in this row of A, this is the number of rows of B that we merge */
1131     const PetscInt *acol = PetscSafePointerPlusOffset(aj, ai[i]); /* column indices of nonzero entries in this row */
1132     PetscInt packlen     = 0, *PETSC_RESTRICT crow;
1133 
1134     /* Pack segrow */
1135     for (j = 0; j < anzi; j++) {
1136       PetscInt brow = acol[j], bjstart = bi[brow], bjend = bi[brow + 1], k;
1137       for (k = bjstart; k < bjend; k++) {
1138         bcol = bj[k];
1139         if (!seen[bcol]) { /* new entry */
1140           PetscInt *PETSC_RESTRICT slot;
1141           PetscCall(PetscSegBufferGetInts(segrow, 1, &slot));
1142           *slot      = bcol;
1143           seen[bcol] = 1;
1144           packlen++;
1145         }
1146       }
1147     }
1148 
1149     /* Check i-th diagonal entry */
1150     if (C->force_diagonals && !seen[i]) {
1151       PetscInt *PETSC_RESTRICT slot;
1152       PetscCall(PetscSegBufferGetInts(segrow, 1, &slot));
1153       *slot   = i;
1154       seen[i] = 1;
1155       packlen++;
1156     }
1157 
1158     PetscCall(PetscSegBufferGetInts(seg, packlen, &crow));
1159     PetscCall(PetscSegBufferExtractTo(segrow, crow));
1160     PetscCall(PetscSortInt(packlen, crow));
1161     ci[i + 1] = ci[i] + packlen;
1162     for (j = 0; j < packlen; j++) seen[crow[j]] = 0;
1163   }
1164   PetscCall(PetscSegBufferDestroy(&segrow));
1165   PetscCall(PetscFree(seen));
1166 
1167   /* Column indices are in the segmented buffer */
1168   PetscCall(PetscSegBufferExtractAlloc(seg, &cj));
1169   PetscCall(PetscSegBufferDestroy(&seg));
1170 
1171   /* put together the new symbolic matrix */
1172   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, NULL, ((PetscObject)A)->type_name, C));
1173   PetscCall(MatSetBlockSizesFromMats(C, A, B));
1174 
1175   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
1176   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
1177   c          = (Mat_SeqAIJ *)C->data;
1178   c->free_a  = PETSC_TRUE;
1179   c->free_ij = PETSC_TRUE;
1180   c->nonew   = 0;
1181 
1182   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted;
1183 
1184   /* set MatInfo */
1185   afill = (PetscReal)ci[am] / PetscMax(ai[am] + bi[bm], 1) + 1.e-5;
1186   if (afill < 1.0) afill = 1.0;
1187   C->info.mallocs           = ndouble;
1188   C->info.fill_ratio_given  = fill;
1189   C->info.fill_ratio_needed = afill;
1190 
1191 #if defined(PETSC_USE_INFO)
1192   if (ci[am]) {
1193     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
1194     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
1195   } else {
1196     PetscCall(PetscInfo(C, "Empty matrix product\n"));
1197   }
1198 #endif
1199   PetscFunctionReturn(PETSC_SUCCESS);
1200 }
1201 
1202 static PetscErrorCode MatDestroy_SeqAIJ_MatMatMultTrans(void *data)
1203 {
1204   Mat_MatMatTransMult *abt = (Mat_MatMatTransMult *)data;
1205 
1206   PetscFunctionBegin;
1207   PetscCall(MatTransposeColoringDestroy(&abt->matcoloring));
1208   PetscCall(MatDestroy(&abt->Bt_den));
1209   PetscCall(MatDestroy(&abt->ABt_den));
1210   PetscCall(PetscFree(abt));
1211   PetscFunctionReturn(PETSC_SUCCESS);
1212 }
1213 
1214 PetscErrorCode MatMatTransposeMultSymbolic_SeqAIJ_SeqAIJ(Mat A, Mat B, PetscReal fill, Mat C)
1215 {
1216   Mat                  Bt;
1217   Mat_MatMatTransMult *abt;
1218   Mat_Product         *product = C->product;
1219   char                *alg;
1220 
1221   PetscFunctionBegin;
1222   PetscCheck(product, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing product struct");
1223   PetscCheck(!product->data, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Extra product struct not empty");
1224 
1225   /* create symbolic Bt */
1226   PetscCall(MatTransposeSymbolic(B, &Bt));
1227   PetscCall(MatSetBlockSizes(Bt, A->cmap->bs, B->cmap->bs));
1228   PetscCall(MatSetType(Bt, ((PetscObject)A)->type_name));
1229 
1230   /* get symbolic C=A*Bt */
1231   PetscCall(PetscStrallocpy(product->alg, &alg));
1232   PetscCall(MatProductSetAlgorithm(C, "sorted")); /* set algorithm for C = A*Bt */
1233   PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ(A, Bt, fill, C));
1234   PetscCall(MatProductSetAlgorithm(C, alg)); /* resume original algorithm for ABt product */
1235   PetscCall(PetscFree(alg));
1236 
1237   /* create a supporting struct for reuse intermediate dense matrices with matcoloring */
1238   PetscCall(PetscNew(&abt));
1239 
1240   product->data    = abt;
1241   product->destroy = MatDestroy_SeqAIJ_MatMatMultTrans;
1242 
1243   C->ops->mattransposemultnumeric = MatMatTransposeMultNumeric_SeqAIJ_SeqAIJ;
1244 
1245   abt->usecoloring = PETSC_FALSE;
1246   PetscCall(PetscStrcmp(product->alg, "color", &abt->usecoloring));
1247   if (abt->usecoloring) {
1248     /* Create MatTransposeColoring from symbolic C=A*B^T */
1249     MatTransposeColoring matcoloring;
1250     MatColoring          coloring;
1251     ISColoring           iscoloring;
1252     Mat                  Bt_dense, C_dense;
1253 
1254     /* inode causes memory problem */
1255     PetscCall(MatSetOption(C, MAT_USE_INODES, PETSC_FALSE));
1256 
1257     PetscCall(MatColoringCreate(C, &coloring));
1258     PetscCall(MatColoringSetDistance(coloring, 2));
1259     PetscCall(MatColoringSetType(coloring, MATCOLORINGSL));
1260     PetscCall(MatColoringSetFromOptions(coloring));
1261     PetscCall(MatColoringApply(coloring, &iscoloring));
1262     PetscCall(MatColoringDestroy(&coloring));
1263     PetscCall(MatTransposeColoringCreate(C, iscoloring, &matcoloring));
1264 
1265     abt->matcoloring = matcoloring;
1266 
1267     PetscCall(ISColoringDestroy(&iscoloring));
1268 
1269     /* Create Bt_dense and C_dense = A*Bt_dense */
1270     PetscCall(MatCreate(PETSC_COMM_SELF, &Bt_dense));
1271     PetscCall(MatSetSizes(Bt_dense, A->cmap->n, matcoloring->ncolors, A->cmap->n, matcoloring->ncolors));
1272     PetscCall(MatSetType(Bt_dense, MATSEQDENSE));
1273     PetscCall(MatSeqDenseSetPreallocation(Bt_dense, NULL));
1274 
1275     Bt_dense->assembled = PETSC_TRUE;
1276     abt->Bt_den         = Bt_dense;
1277 
1278     PetscCall(MatCreate(PETSC_COMM_SELF, &C_dense));
1279     PetscCall(MatSetSizes(C_dense, A->rmap->n, matcoloring->ncolors, A->rmap->n, matcoloring->ncolors));
1280     PetscCall(MatSetType(C_dense, MATSEQDENSE));
1281     PetscCall(MatSeqDenseSetPreallocation(C_dense, NULL));
1282 
1283     Bt_dense->assembled = PETSC_TRUE;
1284     abt->ABt_den        = C_dense;
1285 
1286 #if defined(PETSC_USE_INFO)
1287     {
1288       Mat_SeqAIJ *c = (Mat_SeqAIJ *)C->data;
1289       PetscCall(PetscInfo(C, "Use coloring of C=A*B^T; B^T: %" PetscInt_FMT " %" PetscInt_FMT ", Bt_dense: %" PetscInt_FMT ",%" PetscInt_FMT "; Cnz %" PetscInt_FMT " / (cm*ncolors %" PetscInt_FMT ") = %g\n", B->cmap->n, B->rmap->n, Bt_dense->rmap->n,
1290                           Bt_dense->cmap->n, c->nz, A->rmap->n * matcoloring->ncolors, (double)(((PetscReal)c->nz) / ((PetscReal)(A->rmap->n * matcoloring->ncolors)))));
1291     }
1292 #endif
1293   }
1294   /* clean up */
1295   PetscCall(MatDestroy(&Bt));
1296   PetscFunctionReturn(PETSC_SUCCESS);
1297 }
1298 
1299 PetscErrorCode MatMatTransposeMultNumeric_SeqAIJ_SeqAIJ(Mat A, Mat B, Mat C)
1300 {
1301   Mat_SeqAIJ          *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c = (Mat_SeqAIJ *)C->data;
1302   PetscInt            *ai = a->i, *aj = a->j, *bi = b->i, *bj = b->j, anzi, bnzj, nexta, nextb, *acol, *bcol, brow;
1303   PetscInt             cm = C->rmap->n, *ci = c->i, *cj = c->j, i, j, cnzi, *ccol;
1304   PetscLogDouble       flops = 0.0;
1305   MatScalar           *aa = a->a, *aval, *ba = b->a, *bval, *ca, *cval;
1306   Mat_MatMatTransMult *abt;
1307   Mat_Product         *product = C->product;
1308 
1309   PetscFunctionBegin;
1310   PetscCheck(product, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing product struct");
1311   abt = (Mat_MatMatTransMult *)product->data;
1312   PetscCheck(abt, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing product struct");
1313   /* clear old values in C */
1314   if (!c->a) {
1315     PetscCall(PetscCalloc1(ci[cm] + 1, &ca));
1316     c->a      = ca;
1317     c->free_a = PETSC_TRUE;
1318   } else {
1319     ca = c->a;
1320     PetscCall(PetscArrayzero(ca, ci[cm] + 1));
1321   }
1322 
1323   if (abt->usecoloring) {
1324     MatTransposeColoring matcoloring = abt->matcoloring;
1325     Mat                  Bt_dense, C_dense = abt->ABt_den;
1326 
1327     /* Get Bt_dense by Apply MatTransposeColoring to B */
1328     Bt_dense = abt->Bt_den;
1329     PetscCall(MatTransColoringApplySpToDen(matcoloring, B, Bt_dense));
1330 
1331     /* C_dense = A*Bt_dense */
1332     PetscCall(MatMatMultNumeric_SeqAIJ_SeqDense(A, Bt_dense, C_dense));
1333 
1334     /* Recover C from C_dense */
1335     PetscCall(MatTransColoringApplyDenToSp(matcoloring, C_dense, C));
1336     PetscFunctionReturn(PETSC_SUCCESS);
1337   }
1338 
1339   for (i = 0; i < cm; i++) {
1340     anzi = ai[i + 1] - ai[i];
1341     acol = PetscSafePointerPlusOffset(aj, ai[i]);
1342     aval = PetscSafePointerPlusOffset(aa, ai[i]);
1343     cnzi = ci[i + 1] - ci[i];
1344     ccol = PetscSafePointerPlusOffset(cj, ci[i]);
1345     cval = ca + ci[i];
1346     for (j = 0; j < cnzi; j++) {
1347       brow = ccol[j];
1348       bnzj = bi[brow + 1] - bi[brow];
1349       bcol = bj + bi[brow];
1350       bval = ba + bi[brow];
1351 
1352       /* perform sparse inner-product c(i,j)=A[i,:]*B[j,:]^T */
1353       nexta = 0;
1354       nextb = 0;
1355       while (nexta < anzi && nextb < bnzj) {
1356         while (nexta < anzi && acol[nexta] < bcol[nextb]) nexta++;
1357         if (nexta == anzi) break;
1358         while (nextb < bnzj && acol[nexta] > bcol[nextb]) nextb++;
1359         if (nextb == bnzj) break;
1360         if (acol[nexta] == bcol[nextb]) {
1361           cval[j] += aval[nexta] * bval[nextb];
1362           nexta++;
1363           nextb++;
1364           flops += 2;
1365         }
1366       }
1367     }
1368   }
1369   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
1370   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
1371   PetscCall(PetscLogFlops(flops));
1372   PetscFunctionReturn(PETSC_SUCCESS);
1373 }
1374 
1375 PetscErrorCode MatDestroy_SeqAIJ_MatTransMatMult(void *data)
1376 {
1377   Mat_MatTransMatMult *atb = (Mat_MatTransMatMult *)data;
1378 
1379   PetscFunctionBegin;
1380   PetscCall(MatDestroy(&atb->At));
1381   if (atb->destroy) PetscCall((*atb->destroy)(atb->data));
1382   PetscCall(PetscFree(atb));
1383   PetscFunctionReturn(PETSC_SUCCESS);
1384 }
1385 
1386 PetscErrorCode MatTransposeMatMultSymbolic_SeqAIJ_SeqAIJ(Mat A, Mat B, PetscReal fill, Mat C)
1387 {
1388   Mat          At      = NULL;
1389   Mat_Product *product = C->product;
1390   PetscBool    flg, def, square;
1391 
1392   PetscFunctionBegin;
1393   MatCheckProduct(C, 4);
1394   square = (PetscBool)(A == B && A->symmetric == PETSC_BOOL3_TRUE);
1395   /* outerproduct */
1396   PetscCall(PetscStrcmp(product->alg, "outerproduct", &flg));
1397   if (flg) {
1398     /* create symbolic At */
1399     if (!square) {
1400       PetscCall(MatTransposeSymbolic(A, &At));
1401       PetscCall(MatSetBlockSizes(At, A->cmap->bs, B->cmap->bs));
1402       PetscCall(MatSetType(At, ((PetscObject)A)->type_name));
1403     }
1404     /* get symbolic C=At*B */
1405     PetscCall(MatProductSetAlgorithm(C, "sorted"));
1406     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ(square ? A : At, B, fill, C));
1407 
1408     /* clean up */
1409     if (!square) PetscCall(MatDestroy(&At));
1410 
1411     C->ops->mattransposemultnumeric = MatTransposeMatMultNumeric_SeqAIJ_SeqAIJ; /* outerproduct */
1412     PetscCall(MatProductSetAlgorithm(C, "outerproduct"));
1413     PetscFunctionReturn(PETSC_SUCCESS);
1414   }
1415 
1416   /* matmatmult */
1417   PetscCall(PetscStrcmp(product->alg, "default", &def));
1418   PetscCall(PetscStrcmp(product->alg, "at*b", &flg));
1419   if (flg || def) {
1420     Mat_MatTransMatMult *atb;
1421 
1422     PetscCheck(!product->data, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Extra product struct not empty");
1423     PetscCall(PetscNew(&atb));
1424     if (!square) PetscCall(MatTranspose(A, MAT_INITIAL_MATRIX, &At));
1425     PetscCall(MatProductSetAlgorithm(C, "sorted"));
1426     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ(square ? A : At, B, fill, C));
1427     PetscCall(MatProductSetAlgorithm(C, "at*b"));
1428     product->data    = atb;
1429     product->destroy = MatDestroy_SeqAIJ_MatTransMatMult;
1430     atb->At          = At;
1431 
1432     C->ops->mattransposemultnumeric = NULL; /* see MatProductNumeric_AtB_SeqAIJ_SeqAIJ */
1433     PetscFunctionReturn(PETSC_SUCCESS);
1434   }
1435 
1436   SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "Mat Product Algorithm is not supported");
1437 }
1438 
1439 PetscErrorCode MatTransposeMatMultNumeric_SeqAIJ_SeqAIJ(Mat A, Mat B, Mat C)
1440 {
1441   Mat_SeqAIJ    *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c = (Mat_SeqAIJ *)C->data;
1442   PetscInt       am = A->rmap->n, anzi, *ai = a->i, *aj = a->j, *bi = b->i, *bj, bnzi, nextb;
1443   PetscInt       cm = C->rmap->n, *ci = c->i, *cj = c->j, crow, *cjj, i, j, k;
1444   PetscLogDouble flops = 0.0;
1445   MatScalar     *aa    = a->a, *ba, *ca, *caj;
1446 
1447   PetscFunctionBegin;
1448   if (!c->a) {
1449     PetscCall(PetscCalloc1(ci[cm] + 1, &ca));
1450 
1451     c->a      = ca;
1452     c->free_a = PETSC_TRUE;
1453   } else {
1454     ca = c->a;
1455     PetscCall(PetscArrayzero(ca, ci[cm]));
1456   }
1457 
1458   /* compute A^T*B using outer product (A^T)[:,i]*B[i,:] */
1459   for (i = 0; i < am; i++) {
1460     bj   = b->j + bi[i];
1461     ba   = b->a + bi[i];
1462     bnzi = bi[i + 1] - bi[i];
1463     anzi = ai[i + 1] - ai[i];
1464     for (j = 0; j < anzi; j++) {
1465       nextb = 0;
1466       crow  = *aj++;
1467       cjj   = cj + ci[crow];
1468       caj   = ca + ci[crow];
1469       /* perform sparse axpy operation.  Note cjj includes bj. */
1470       for (k = 0; nextb < bnzi; k++) {
1471         if (cjj[k] == *(bj + nextb)) { /* ccol == bcol */
1472           caj[k] += (*aa) * (*(ba + nextb));
1473           nextb++;
1474         }
1475       }
1476       flops += 2 * bnzi;
1477       aa++;
1478     }
1479   }
1480 
1481   /* Assemble the final matrix and clean up */
1482   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
1483   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
1484   PetscCall(PetscLogFlops(flops));
1485   PetscFunctionReturn(PETSC_SUCCESS);
1486 }
1487 
1488 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqDense(Mat A, Mat B, PetscReal fill, Mat C)
1489 {
1490   PetscFunctionBegin;
1491   PetscCall(MatMatMultSymbolic_SeqDense_SeqDense(A, B, 0.0, C));
1492   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqDense;
1493   PetscFunctionReturn(PETSC_SUCCESS);
1494 }
1495 
1496 PETSC_INTERN PetscErrorCode MatMatMultNumericAdd_SeqAIJ_SeqDense(Mat A, Mat B, Mat C, const PetscBool add)
1497 {
1498   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data;
1499   PetscScalar       *c, r1, r2, r3, r4, *c1, *c2, *c3, *c4;
1500   const PetscScalar *aa, *b, *b1, *b2, *b3, *b4, *av;
1501   const PetscInt    *aj;
1502   PetscInt           cm = C->rmap->n, cn = B->cmap->n, bm, am = A->rmap->n;
1503   PetscInt           clda;
1504   PetscInt           am4, bm4, col, i, j, n;
1505 
1506   PetscFunctionBegin;
1507   if (!cm || !cn) PetscFunctionReturn(PETSC_SUCCESS);
1508   PetscCall(MatSeqAIJGetArrayRead(A, &av));
1509   if (add) {
1510     PetscCall(MatDenseGetArray(C, &c));
1511   } else {
1512     PetscCall(MatDenseGetArrayWrite(C, &c));
1513   }
1514   PetscCall(MatDenseGetArrayRead(B, &b));
1515   PetscCall(MatDenseGetLDA(B, &bm));
1516   PetscCall(MatDenseGetLDA(C, &clda));
1517   am4 = 4 * clda;
1518   bm4 = 4 * bm;
1519   if (b) {
1520     b1 = b;
1521     b2 = b1 + bm;
1522     b3 = b2 + bm;
1523     b4 = b3 + bm;
1524   } else b1 = b2 = b3 = b4 = NULL;
1525   c1 = c;
1526   c2 = c1 + clda;
1527   c3 = c2 + clda;
1528   c4 = c3 + clda;
1529   for (col = 0; col < (cn / 4) * 4; col += 4) { /* over columns of C */
1530     for (i = 0; i < am; i++) {                  /* over rows of A in those columns */
1531       r1 = r2 = r3 = r4 = 0.0;
1532       n                 = a->i[i + 1] - a->i[i];
1533       aj                = PetscSafePointerPlusOffset(a->j, a->i[i]);
1534       aa                = PetscSafePointerPlusOffset(av, a->i[i]);
1535       for (j = 0; j < n; j++) {
1536         const PetscScalar aatmp = aa[j];
1537         const PetscInt    ajtmp = aj[j];
1538         r1 += aatmp * b1[ajtmp];
1539         r2 += aatmp * b2[ajtmp];
1540         r3 += aatmp * b3[ajtmp];
1541         r4 += aatmp * b4[ajtmp];
1542       }
1543       if (add) {
1544         c1[i] += r1;
1545         c2[i] += r2;
1546         c3[i] += r3;
1547         c4[i] += r4;
1548       } else {
1549         c1[i] = r1;
1550         c2[i] = r2;
1551         c3[i] = r3;
1552         c4[i] = r4;
1553       }
1554     }
1555     if (b) {
1556       b1 += bm4;
1557       b2 += bm4;
1558       b3 += bm4;
1559       b4 += bm4;
1560     }
1561     c1 += am4;
1562     c2 += am4;
1563     c3 += am4;
1564     c4 += am4;
1565   }
1566   /* process remaining columns */
1567   if (col != cn) {
1568     PetscInt rc = cn - col;
1569 
1570     if (rc == 1) {
1571       for (i = 0; i < am; i++) {
1572         r1 = 0.0;
1573         n  = a->i[i + 1] - a->i[i];
1574         aj = PetscSafePointerPlusOffset(a->j, a->i[i]);
1575         aa = PetscSafePointerPlusOffset(av, a->i[i]);
1576         for (j = 0; j < n; j++) r1 += aa[j] * b1[aj[j]];
1577         if (add) c1[i] += r1;
1578         else c1[i] = r1;
1579       }
1580     } else if (rc == 2) {
1581       for (i = 0; i < am; i++) {
1582         r1 = r2 = 0.0;
1583         n       = a->i[i + 1] - a->i[i];
1584         aj      = PetscSafePointerPlusOffset(a->j, a->i[i]);
1585         aa      = PetscSafePointerPlusOffset(av, a->i[i]);
1586         for (j = 0; j < n; j++) {
1587           const PetscScalar aatmp = aa[j];
1588           const PetscInt    ajtmp = aj[j];
1589           r1 += aatmp * b1[ajtmp];
1590           r2 += aatmp * b2[ajtmp];
1591         }
1592         if (add) {
1593           c1[i] += r1;
1594           c2[i] += r2;
1595         } else {
1596           c1[i] = r1;
1597           c2[i] = r2;
1598         }
1599       }
1600     } else {
1601       for (i = 0; i < am; i++) {
1602         r1 = r2 = r3 = 0.0;
1603         n            = a->i[i + 1] - a->i[i];
1604         aj           = PetscSafePointerPlusOffset(a->j, a->i[i]);
1605         aa           = PetscSafePointerPlusOffset(av, a->i[i]);
1606         for (j = 0; j < n; j++) {
1607           const PetscScalar aatmp = aa[j];
1608           const PetscInt    ajtmp = aj[j];
1609           r1 += aatmp * b1[ajtmp];
1610           r2 += aatmp * b2[ajtmp];
1611           r3 += aatmp * b3[ajtmp];
1612         }
1613         if (add) {
1614           c1[i] += r1;
1615           c2[i] += r2;
1616           c3[i] += r3;
1617         } else {
1618           c1[i] = r1;
1619           c2[i] = r2;
1620           c3[i] = r3;
1621         }
1622       }
1623     }
1624   }
1625   PetscCall(PetscLogFlops(cn * (2.0 * a->nz)));
1626   if (add) {
1627     PetscCall(MatDenseRestoreArray(C, &c));
1628   } else {
1629     PetscCall(MatDenseRestoreArrayWrite(C, &c));
1630   }
1631   PetscCall(MatDenseRestoreArrayRead(B, &b));
1632   PetscCall(MatSeqAIJRestoreArrayRead(A, &av));
1633   PetscFunctionReturn(PETSC_SUCCESS);
1634 }
1635 
1636 PetscErrorCode MatMatMultNumeric_SeqAIJ_SeqDense(Mat A, Mat B, Mat C)
1637 {
1638   PetscFunctionBegin;
1639   PetscCheck(B->rmap->n == A->cmap->n, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Number columns in A %" PetscInt_FMT " not equal rows in B %" PetscInt_FMT, A->cmap->n, B->rmap->n);
1640   PetscCheck(A->rmap->n == C->rmap->n, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Number rows in C %" PetscInt_FMT " not equal rows in A %" PetscInt_FMT, C->rmap->n, A->rmap->n);
1641   PetscCheck(B->cmap->n == C->cmap->n, PETSC_COMM_SELF, PETSC_ERR_ARG_SIZ, "Number columns in B %" PetscInt_FMT " not equal columns in C %" PetscInt_FMT, B->cmap->n, C->cmap->n);
1642 
1643   PetscCall(MatMatMultNumericAdd_SeqAIJ_SeqDense(A, B, C, PETSC_FALSE));
1644   PetscFunctionReturn(PETSC_SUCCESS);
1645 }
1646 
1647 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_SeqDense_AB(Mat C)
1648 {
1649   PetscFunctionBegin;
1650   C->ops->matmultsymbolic = MatMatMultSymbolic_SeqAIJ_SeqDense;
1651   C->ops->productsymbolic = MatProductSymbolic_AB;
1652   PetscFunctionReturn(PETSC_SUCCESS);
1653 }
1654 
1655 PETSC_INTERN PetscErrorCode MatTMatTMultSymbolic_SeqAIJ_SeqDense(Mat, Mat, PetscReal, Mat);
1656 
1657 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_SeqDense_AtB(Mat C)
1658 {
1659   PetscFunctionBegin;
1660   C->ops->transposematmultsymbolic = MatTMatTMultSymbolic_SeqAIJ_SeqDense;
1661   C->ops->productsymbolic          = MatProductSymbolic_AtB;
1662   PetscFunctionReturn(PETSC_SUCCESS);
1663 }
1664 
1665 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_SeqDense_ABt(Mat C)
1666 {
1667   PetscFunctionBegin;
1668   C->ops->mattransposemultsymbolic = MatTMatTMultSymbolic_SeqAIJ_SeqDense;
1669   C->ops->productsymbolic          = MatProductSymbolic_ABt;
1670   PetscFunctionReturn(PETSC_SUCCESS);
1671 }
1672 
1673 PETSC_INTERN PetscErrorCode MatProductSetFromOptions_SeqAIJ_SeqDense(Mat C)
1674 {
1675   Mat_Product *product = C->product;
1676 
1677   PetscFunctionBegin;
1678   switch (product->type) {
1679   case MATPRODUCT_AB:
1680     PetscCall(MatProductSetFromOptions_SeqAIJ_SeqDense_AB(C));
1681     break;
1682   case MATPRODUCT_AtB:
1683     PetscCall(MatProductSetFromOptions_SeqAIJ_SeqDense_AtB(C));
1684     break;
1685   case MATPRODUCT_ABt:
1686     PetscCall(MatProductSetFromOptions_SeqAIJ_SeqDense_ABt(C));
1687     break;
1688   default:
1689     break;
1690   }
1691   PetscFunctionReturn(PETSC_SUCCESS);
1692 }
1693 
1694 static PetscErrorCode MatProductSetFromOptions_SeqXBAIJ_SeqDense_AB(Mat C)
1695 {
1696   Mat_Product *product = C->product;
1697   Mat          A       = product->A;
1698   PetscBool    baij;
1699 
1700   PetscFunctionBegin;
1701   PetscCall(PetscObjectTypeCompare((PetscObject)A, MATSEQBAIJ, &baij));
1702   if (!baij) { /* A is seqsbaij */
1703     PetscBool sbaij;
1704     PetscCall(PetscObjectTypeCompare((PetscObject)A, MATSEQSBAIJ, &sbaij));
1705     PetscCheck(sbaij, PetscObjectComm((PetscObject)C), PETSC_ERR_ARG_WRONGSTATE, "Mat must be either seqbaij or seqsbaij format");
1706 
1707     C->ops->matmultsymbolic = MatMatMultSymbolic_SeqSBAIJ_SeqDense;
1708   } else { /* A is seqbaij */
1709     C->ops->matmultsymbolic = MatMatMultSymbolic_SeqBAIJ_SeqDense;
1710   }
1711 
1712   C->ops->productsymbolic = MatProductSymbolic_AB;
1713   PetscFunctionReturn(PETSC_SUCCESS);
1714 }
1715 
1716 PETSC_INTERN PetscErrorCode MatProductSetFromOptions_SeqXBAIJ_SeqDense(Mat C)
1717 {
1718   Mat_Product *product = C->product;
1719 
1720   PetscFunctionBegin;
1721   MatCheckProduct(C, 1);
1722   PetscCheck(product->A, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing A");
1723   if (product->type == MATPRODUCT_AB || (product->type == MATPRODUCT_AtB && product->A->symmetric == PETSC_BOOL3_TRUE)) PetscCall(MatProductSetFromOptions_SeqXBAIJ_SeqDense_AB(C));
1724   PetscFunctionReturn(PETSC_SUCCESS);
1725 }
1726 
1727 static PetscErrorCode MatProductSetFromOptions_SeqDense_SeqAIJ_AB(Mat C)
1728 {
1729   PetscFunctionBegin;
1730   C->ops->matmultsymbolic = MatMatMultSymbolic_SeqDense_SeqAIJ;
1731   C->ops->productsymbolic = MatProductSymbolic_AB;
1732   PetscFunctionReturn(PETSC_SUCCESS);
1733 }
1734 
1735 PETSC_INTERN PetscErrorCode MatProductSetFromOptions_SeqDense_SeqAIJ(Mat C)
1736 {
1737   Mat_Product *product = C->product;
1738 
1739   PetscFunctionBegin;
1740   if (product->type == MATPRODUCT_AB) PetscCall(MatProductSetFromOptions_SeqDense_SeqAIJ_AB(C));
1741   PetscFunctionReturn(PETSC_SUCCESS);
1742 }
1743 
1744 PetscErrorCode MatTransColoringApplySpToDen_SeqAIJ(MatTransposeColoring coloring, Mat B, Mat Btdense)
1745 {
1746   Mat_SeqAIJ   *b       = (Mat_SeqAIJ *)B->data;
1747   Mat_SeqDense *btdense = (Mat_SeqDense *)Btdense->data;
1748   PetscInt     *bi = b->i, *bj = b->j;
1749   PetscInt      m = Btdense->rmap->n, n = Btdense->cmap->n, j, k, l, col, anz, *btcol, brow, ncolumns;
1750   MatScalar    *btval, *btval_den, *ba = b->a;
1751   PetscInt     *columns = coloring->columns, *colorforcol = coloring->colorforcol, ncolors = coloring->ncolors;
1752 
1753   PetscFunctionBegin;
1754   btval_den = btdense->v;
1755   PetscCall(PetscArrayzero(btval_den, m * n));
1756   for (k = 0; k < ncolors; k++) {
1757     ncolumns = coloring->ncolumns[k];
1758     for (l = 0; l < ncolumns; l++) { /* insert a row of B to a column of Btdense */
1759       col   = *(columns + colorforcol[k] + l);
1760       btcol = bj + bi[col];
1761       btval = ba + bi[col];
1762       anz   = bi[col + 1] - bi[col];
1763       for (j = 0; j < anz; j++) {
1764         brow            = btcol[j];
1765         btval_den[brow] = btval[j];
1766       }
1767     }
1768     btval_den += m;
1769   }
1770   PetscFunctionReturn(PETSC_SUCCESS);
1771 }
1772 
1773 PetscErrorCode MatTransColoringApplyDenToSp_SeqAIJ(MatTransposeColoring matcoloring, Mat Cden, Mat Csp)
1774 {
1775   Mat_SeqAIJ        *csp = (Mat_SeqAIJ *)Csp->data;
1776   const PetscScalar *ca_den, *ca_den_ptr;
1777   PetscScalar       *ca = csp->a;
1778   PetscInt           k, l, m = Cden->rmap->n, ncolors = matcoloring->ncolors;
1779   PetscInt           brows = matcoloring->brows, *den2sp = matcoloring->den2sp;
1780   PetscInt           nrows, *row, *idx;
1781   PetscInt          *rows = matcoloring->rows, *colorforrow = matcoloring->colorforrow;
1782 
1783   PetscFunctionBegin;
1784   PetscCall(MatDenseGetArrayRead(Cden, &ca_den));
1785 
1786   if (brows > 0) {
1787     PetscInt *lstart, row_end, row_start;
1788     lstart = matcoloring->lstart;
1789     PetscCall(PetscArrayzero(lstart, ncolors));
1790 
1791     row_end = brows;
1792     if (row_end > m) row_end = m;
1793     for (row_start = 0; row_start < m; row_start += brows) { /* loop over row blocks of Csp */
1794       ca_den_ptr = ca_den;
1795       for (k = 0; k < ncolors; k++) { /* loop over colors (columns of Cden) */
1796         nrows = matcoloring->nrows[k];
1797         row   = rows + colorforrow[k];
1798         idx   = den2sp + colorforrow[k];
1799         for (l = lstart[k]; l < nrows; l++) {
1800           if (row[l] >= row_end) {
1801             lstart[k] = l;
1802             break;
1803           } else {
1804             ca[idx[l]] = ca_den_ptr[row[l]];
1805           }
1806         }
1807         ca_den_ptr += m;
1808       }
1809       row_end += brows;
1810       if (row_end > m) row_end = m;
1811     }
1812   } else { /* non-blocked impl: loop over columns of Csp - slow if Csp is large */
1813     ca_den_ptr = ca_den;
1814     for (k = 0; k < ncolors; k++) {
1815       nrows = matcoloring->nrows[k];
1816       row   = rows + colorforrow[k];
1817       idx   = den2sp + colorforrow[k];
1818       for (l = 0; l < nrows; l++) ca[idx[l]] = ca_den_ptr[row[l]];
1819       ca_den_ptr += m;
1820     }
1821   }
1822 
1823   PetscCall(MatDenseRestoreArrayRead(Cden, &ca_den));
1824 #if defined(PETSC_USE_INFO)
1825   if (matcoloring->brows > 0) {
1826     PetscCall(PetscInfo(Csp, "Loop over %" PetscInt_FMT " row blocks for den2sp\n", brows));
1827   } else {
1828     PetscCall(PetscInfo(Csp, "Loop over colors/columns of Cden, inefficient for large sparse matrix product \n"));
1829   }
1830 #endif
1831   PetscFunctionReturn(PETSC_SUCCESS);
1832 }
1833 
1834 PetscErrorCode MatTransposeColoringCreate_SeqAIJ(Mat mat, ISColoring iscoloring, MatTransposeColoring c)
1835 {
1836   PetscInt        i, n, nrows, Nbs, j, k, m, ncols, col, cm;
1837   const PetscInt *is, *ci, *cj, *row_idx;
1838   PetscInt        nis = iscoloring->n, *rowhit, bs = 1;
1839   IS             *isa;
1840   Mat_SeqAIJ     *csp = (Mat_SeqAIJ *)mat->data;
1841   PetscInt       *colorforrow, *rows, *rows_i, *idxhit, *spidx, *den2sp, *den2sp_i;
1842   PetscInt       *colorforcol, *columns, *columns_i, brows;
1843   PetscBool       flg;
1844 
1845   PetscFunctionBegin;
1846   PetscCall(ISColoringGetIS(iscoloring, PETSC_USE_POINTER, PETSC_IGNORE, &isa));
1847 
1848   /* bs > 1 is not being tested yet! */
1849   Nbs       = mat->cmap->N / bs;
1850   c->M      = mat->rmap->N / bs; /* set total rows, columns and local rows */
1851   c->N      = Nbs;
1852   c->m      = c->M;
1853   c->rstart = 0;
1854   c->brows  = 100;
1855 
1856   c->ncolors = nis;
1857   PetscCall(PetscMalloc3(nis, &c->ncolumns, nis, &c->nrows, nis + 1, &colorforrow));
1858   PetscCall(PetscMalloc1(csp->nz + 1, &rows));
1859   PetscCall(PetscMalloc1(csp->nz + 1, &den2sp));
1860 
1861   brows = c->brows;
1862   PetscCall(PetscOptionsGetInt(NULL, NULL, "-matden2sp_brows", &brows, &flg));
1863   if (flg) c->brows = brows;
1864   if (brows > 0) PetscCall(PetscMalloc1(nis + 1, &c->lstart));
1865 
1866   colorforrow[0] = 0;
1867   rows_i         = rows;
1868   den2sp_i       = den2sp;
1869 
1870   PetscCall(PetscMalloc1(nis + 1, &colorforcol));
1871   PetscCall(PetscMalloc1(Nbs + 1, &columns));
1872 
1873   colorforcol[0] = 0;
1874   columns_i      = columns;
1875 
1876   /* get column-wise storage of mat */
1877   PetscCall(MatGetColumnIJ_SeqAIJ_Color(mat, 0, PETSC_FALSE, PETSC_FALSE, &ncols, &ci, &cj, &spidx, NULL));
1878 
1879   cm = c->m;
1880   PetscCall(PetscMalloc1(cm + 1, &rowhit));
1881   PetscCall(PetscMalloc1(cm + 1, &idxhit));
1882   for (i = 0; i < nis; i++) { /* loop over color */
1883     PetscCall(ISGetLocalSize(isa[i], &n));
1884     PetscCall(ISGetIndices(isa[i], &is));
1885 
1886     c->ncolumns[i] = n;
1887     if (n) PetscCall(PetscArraycpy(columns_i, is, n));
1888     colorforcol[i + 1] = colorforcol[i] + n;
1889     columns_i += n;
1890 
1891     /* fast, crude version requires O(N*N) work */
1892     PetscCall(PetscArrayzero(rowhit, cm));
1893 
1894     for (j = 0; j < n; j++) { /* loop over columns*/
1895       col     = is[j];
1896       row_idx = cj + ci[col];
1897       m       = ci[col + 1] - ci[col];
1898       for (k = 0; k < m; k++) { /* loop over columns marking them in rowhit */
1899         idxhit[*row_idx]   = spidx[ci[col] + k];
1900         rowhit[*row_idx++] = col + 1;
1901       }
1902     }
1903     /* count the number of hits */
1904     nrows = 0;
1905     for (j = 0; j < cm; j++) {
1906       if (rowhit[j]) nrows++;
1907     }
1908     c->nrows[i]        = nrows;
1909     colorforrow[i + 1] = colorforrow[i] + nrows;
1910 
1911     nrows = 0;
1912     for (j = 0; j < cm; j++) { /* loop over rows */
1913       if (rowhit[j]) {
1914         rows_i[nrows]   = j;
1915         den2sp_i[nrows] = idxhit[j];
1916         nrows++;
1917       }
1918     }
1919     den2sp_i += nrows;
1920 
1921     PetscCall(ISRestoreIndices(isa[i], &is));
1922     rows_i += nrows;
1923   }
1924   PetscCall(MatRestoreColumnIJ_SeqAIJ_Color(mat, 0, PETSC_FALSE, PETSC_FALSE, &ncols, &ci, &cj, &spidx, NULL));
1925   PetscCall(PetscFree(rowhit));
1926   PetscCall(ISColoringRestoreIS(iscoloring, PETSC_USE_POINTER, &isa));
1927   PetscCheck(csp->nz == colorforrow[nis], PETSC_COMM_SELF, PETSC_ERR_PLIB, "csp->nz %" PetscInt_FMT " != colorforrow[nis] %" PetscInt_FMT, csp->nz, colorforrow[nis]);
1928 
1929   c->colorforrow = colorforrow;
1930   c->rows        = rows;
1931   c->den2sp      = den2sp;
1932   c->colorforcol = colorforcol;
1933   c->columns     = columns;
1934 
1935   PetscCall(PetscFree(idxhit));
1936   PetscFunctionReturn(PETSC_SUCCESS);
1937 }
1938 
1939 static PetscErrorCode MatProductNumeric_AtB_SeqAIJ_SeqAIJ(Mat C)
1940 {
1941   Mat_Product *product = C->product;
1942   Mat          A = product->A, B = product->B;
1943 
1944   PetscFunctionBegin;
1945   if (C->ops->mattransposemultnumeric) {
1946     /* Alg: "outerproduct" */
1947     PetscCall((*C->ops->mattransposemultnumeric)(A, B, C));
1948   } else {
1949     /* Alg: "matmatmult" -- C = At*B */
1950     Mat_MatTransMatMult *atb = (Mat_MatTransMatMult *)product->data;
1951 
1952     PetscCheck(atb, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing product struct");
1953     if (atb->At) {
1954       /* At is computed in MatTransposeMatMultSymbolic_SeqAIJ_SeqAIJ();
1955          user may have called MatProductReplaceMats() to get this A=product->A */
1956       PetscCall(MatTransposeSetPrecursor(A, atb->At));
1957       PetscCall(MatTranspose(A, MAT_REUSE_MATRIX, &atb->At));
1958     }
1959     PetscCall(MatMatMultNumeric_SeqAIJ_SeqAIJ(atb->At ? atb->At : A, B, C));
1960   }
1961   PetscFunctionReturn(PETSC_SUCCESS);
1962 }
1963 
1964 static PetscErrorCode MatProductSymbolic_AtB_SeqAIJ_SeqAIJ(Mat C)
1965 {
1966   Mat_Product *product = C->product;
1967   Mat          A = product->A, B = product->B;
1968   PetscReal    fill = product->fill;
1969 
1970   PetscFunctionBegin;
1971   PetscCall(MatTransposeMatMultSymbolic_SeqAIJ_SeqAIJ(A, B, fill, C));
1972 
1973   C->ops->productnumeric = MatProductNumeric_AtB_SeqAIJ_SeqAIJ;
1974   PetscFunctionReturn(PETSC_SUCCESS);
1975 }
1976 
1977 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_AB(Mat C)
1978 {
1979   Mat_Product *product = C->product;
1980   PetscInt     alg     = 0; /* default algorithm */
1981   PetscBool    flg     = PETSC_FALSE;
1982 #if !defined(PETSC_HAVE_HYPRE)
1983   const char *algTypes[7] = {"sorted", "scalable", "scalable_fast", "heap", "btheap", "llcondensed", "rowmerge"};
1984   PetscInt    nalg        = 7;
1985 #else
1986   const char *algTypes[8] = {"sorted", "scalable", "scalable_fast", "heap", "btheap", "llcondensed", "rowmerge", "hypre"};
1987   PetscInt    nalg        = 8;
1988 #endif
1989 
1990   PetscFunctionBegin;
1991   /* Set default algorithm */
1992   PetscCall(PetscStrcmp(C->product->alg, "default", &flg));
1993   if (flg) PetscCall(MatProductSetAlgorithm(C, algTypes[alg]));
1994 
1995   /* Get runtime option */
1996   if (product->api_user) {
1997     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatMatMult", "Mat");
1998     PetscCall(PetscOptionsEList("-matmatmult_via", "Algorithmic approach", "MatMatMult", algTypes, nalg, algTypes[0], &alg, &flg));
1999     PetscOptionsEnd();
2000   } else {
2001     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_AB", "Mat");
2002     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_AB", algTypes, nalg, algTypes[0], &alg, &flg));
2003     PetscOptionsEnd();
2004   }
2005   if (flg) PetscCall(MatProductSetAlgorithm(C, algTypes[alg]));
2006 
2007   C->ops->productsymbolic = MatProductSymbolic_AB;
2008   C->ops->matmultsymbolic = MatMatMultSymbolic_SeqAIJ_SeqAIJ;
2009   PetscFunctionReturn(PETSC_SUCCESS);
2010 }
2011 
2012 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_AtB(Mat C)
2013 {
2014   Mat_Product *product     = C->product;
2015   PetscInt     alg         = 0; /* default algorithm */
2016   PetscBool    flg         = PETSC_FALSE;
2017   const char  *algTypes[3] = {"default", "at*b", "outerproduct"};
2018   PetscInt     nalg        = 3;
2019 
2020   PetscFunctionBegin;
2021   /* Get runtime option */
2022   if (product->api_user) {
2023     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatTransposeMatMult", "Mat");
2024     PetscCall(PetscOptionsEList("-mattransposematmult_via", "Algorithmic approach", "MatTransposeMatMult", algTypes, nalg, algTypes[alg], &alg, &flg));
2025     PetscOptionsEnd();
2026   } else {
2027     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_AtB", "Mat");
2028     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_AtB", algTypes, nalg, algTypes[alg], &alg, &flg));
2029     PetscOptionsEnd();
2030   }
2031   if (flg) PetscCall(MatProductSetAlgorithm(C, algTypes[alg]));
2032 
2033   C->ops->productsymbolic = MatProductSymbolic_AtB_SeqAIJ_SeqAIJ;
2034   PetscFunctionReturn(PETSC_SUCCESS);
2035 }
2036 
2037 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_ABt(Mat C)
2038 {
2039   Mat_Product *product     = C->product;
2040   PetscInt     alg         = 0; /* default algorithm */
2041   PetscBool    flg         = PETSC_FALSE;
2042   const char  *algTypes[2] = {"default", "color"};
2043   PetscInt     nalg        = 2;
2044 
2045   PetscFunctionBegin;
2046   /* Set default algorithm */
2047   PetscCall(PetscStrcmp(C->product->alg, "default", &flg));
2048   if (!flg) {
2049     alg = 1;
2050     PetscCall(MatProductSetAlgorithm(C, algTypes[alg]));
2051   }
2052 
2053   /* Get runtime option */
2054   if (product->api_user) {
2055     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatMatTransposeMult", "Mat");
2056     PetscCall(PetscOptionsEList("-matmattransmult_via", "Algorithmic approach", "MatMatTransposeMult", algTypes, nalg, algTypes[alg], &alg, &flg));
2057     PetscOptionsEnd();
2058   } else {
2059     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_ABt", "Mat");
2060     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_ABt", algTypes, nalg, algTypes[alg], &alg, &flg));
2061     PetscOptionsEnd();
2062   }
2063   if (flg) PetscCall(MatProductSetAlgorithm(C, algTypes[alg]));
2064 
2065   C->ops->mattransposemultsymbolic = MatMatTransposeMultSymbolic_SeqAIJ_SeqAIJ;
2066   C->ops->productsymbolic          = MatProductSymbolic_ABt;
2067   PetscFunctionReturn(PETSC_SUCCESS);
2068 }
2069 
2070 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_PtAP(Mat C)
2071 {
2072   Mat_Product *product = C->product;
2073   PetscBool    flg     = PETSC_FALSE;
2074   PetscInt     alg     = 0; /* default algorithm -- alg=1 should be default!!! */
2075 #if !defined(PETSC_HAVE_HYPRE)
2076   const char *algTypes[2] = {"scalable", "rap"};
2077   PetscInt    nalg        = 2;
2078 #else
2079   const char *algTypes[3] = {"scalable", "rap", "hypre"};
2080   PetscInt    nalg        = 3;
2081 #endif
2082 
2083   PetscFunctionBegin;
2084   /* Set default algorithm */
2085   PetscCall(PetscStrcmp(product->alg, "default", &flg));
2086   if (flg) PetscCall(MatProductSetAlgorithm(C, algTypes[alg]));
2087 
2088   /* Get runtime option */
2089   if (product->api_user) {
2090     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatPtAP", "Mat");
2091     PetscCall(PetscOptionsEList("-matptap_via", "Algorithmic approach", "MatPtAP", algTypes, nalg, algTypes[0], &alg, &flg));
2092     PetscOptionsEnd();
2093   } else {
2094     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_PtAP", "Mat");
2095     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_PtAP", algTypes, nalg, algTypes[0], &alg, &flg));
2096     PetscOptionsEnd();
2097   }
2098   if (flg) PetscCall(MatProductSetAlgorithm(C, algTypes[alg]));
2099 
2100   C->ops->productsymbolic = MatProductSymbolic_PtAP_SeqAIJ_SeqAIJ;
2101   PetscFunctionReturn(PETSC_SUCCESS);
2102 }
2103 
2104 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_RARt(Mat C)
2105 {
2106   Mat_Product *product     = C->product;
2107   PetscBool    flg         = PETSC_FALSE;
2108   PetscInt     alg         = 0; /* default algorithm */
2109   const char  *algTypes[3] = {"r*a*rt", "r*art", "coloring_rart"};
2110   PetscInt     nalg        = 3;
2111 
2112   PetscFunctionBegin;
2113   /* Set default algorithm */
2114   PetscCall(PetscStrcmp(product->alg, "default", &flg));
2115   if (flg) PetscCall(MatProductSetAlgorithm(C, algTypes[alg]));
2116 
2117   /* Get runtime option */
2118   if (product->api_user) {
2119     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatRARt", "Mat");
2120     PetscCall(PetscOptionsEList("-matrart_via", "Algorithmic approach", "MatRARt", algTypes, nalg, algTypes[0], &alg, &flg));
2121     PetscOptionsEnd();
2122   } else {
2123     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_RARt", "Mat");
2124     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_RARt", algTypes, nalg, algTypes[0], &alg, &flg));
2125     PetscOptionsEnd();
2126   }
2127   if (flg) PetscCall(MatProductSetAlgorithm(C, algTypes[alg]));
2128 
2129   C->ops->productsymbolic = MatProductSymbolic_RARt_SeqAIJ_SeqAIJ;
2130   PetscFunctionReturn(PETSC_SUCCESS);
2131 }
2132 
2133 /* ABC = A*B*C = A*(B*C); ABC's algorithm must be chosen from AB's algorithm */
2134 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_ABC(Mat C)
2135 {
2136   Mat_Product *product     = C->product;
2137   PetscInt     alg         = 0; /* default algorithm */
2138   PetscBool    flg         = PETSC_FALSE;
2139   const char  *algTypes[7] = {"sorted", "scalable", "scalable_fast", "heap", "btheap", "llcondensed", "rowmerge"};
2140   PetscInt     nalg        = 7;
2141 
2142   PetscFunctionBegin;
2143   /* Set default algorithm */
2144   PetscCall(PetscStrcmp(product->alg, "default", &flg));
2145   if (flg) PetscCall(MatProductSetAlgorithm(C, algTypes[alg]));
2146 
2147   /* Get runtime option */
2148   if (product->api_user) {
2149     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatMatMatMult", "Mat");
2150     PetscCall(PetscOptionsEList("-matmatmatmult_via", "Algorithmic approach", "MatMatMatMult", algTypes, nalg, algTypes[alg], &alg, &flg));
2151     PetscOptionsEnd();
2152   } else {
2153     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_ABC", "Mat");
2154     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_ABC", algTypes, nalg, algTypes[alg], &alg, &flg));
2155     PetscOptionsEnd();
2156   }
2157   if (flg) PetscCall(MatProductSetAlgorithm(C, algTypes[alg]));
2158 
2159   C->ops->matmatmultsymbolic = MatMatMatMultSymbolic_SeqAIJ_SeqAIJ_SeqAIJ;
2160   C->ops->productsymbolic    = MatProductSymbolic_ABC;
2161   PetscFunctionReturn(PETSC_SUCCESS);
2162 }
2163 
2164 PetscErrorCode MatProductSetFromOptions_SeqAIJ(Mat C)
2165 {
2166   Mat_Product *product = C->product;
2167 
2168   PetscFunctionBegin;
2169   switch (product->type) {
2170   case MATPRODUCT_AB:
2171     PetscCall(MatProductSetFromOptions_SeqAIJ_AB(C));
2172     break;
2173   case MATPRODUCT_AtB:
2174     PetscCall(MatProductSetFromOptions_SeqAIJ_AtB(C));
2175     break;
2176   case MATPRODUCT_ABt:
2177     PetscCall(MatProductSetFromOptions_SeqAIJ_ABt(C));
2178     break;
2179   case MATPRODUCT_PtAP:
2180     PetscCall(MatProductSetFromOptions_SeqAIJ_PtAP(C));
2181     break;
2182   case MATPRODUCT_RARt:
2183     PetscCall(MatProductSetFromOptions_SeqAIJ_RARt(C));
2184     break;
2185   case MATPRODUCT_ABC:
2186     PetscCall(MatProductSetFromOptions_SeqAIJ_ABC(C));
2187     break;
2188   default:
2189     break;
2190   }
2191   PetscFunctionReturn(PETSC_SUCCESS);
2192 }
2193