xref: /petsc/src/mat/impls/aij/seq/matmatmult.c (revision 98d129c30f3ee9fdddc40fdbc5a989b7be64f888)
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, osingle, 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   osingle  = aij->singlemalloc;
40   ofree_a  = aij->free_a;
41   ofree_ij = aij->free_ij;
42   /* changes the free flags */
43   PetscCall(MatSeqAIJSetPreallocation_SeqAIJ(mat, MAT_SKIP_ALLOCATION, NULL));
44 
45   PetscCall(PetscFree(aij->ilen));
46   PetscCall(PetscFree(aij->imax));
47   PetscCall(PetscMalloc1(m, &aij->imax));
48   PetscCall(PetscMalloc1(m, &aij->ilen));
49   for (ii = 0, aij->nonzerorowcnt = 0, aij->rmax = 0; ii < m; ii++) {
50     const PetscInt rnz = i[ii + 1] - i[ii];
51     aij->nonzerorowcnt += !!rnz;
52     aij->rmax     = PetscMax(aij->rmax, rnz);
53     aij->ilen[ii] = aij->imax[ii] = i[ii + 1] - i[ii];
54   }
55   aij->maxnz = i[m];
56   aij->nz    = i[m];
57 
58   if (osingle) {
59     PetscCall(PetscFree3(aij->a, aij->j, aij->i));
60   } else {
61     if (ofree_a) PetscCall(PetscFree(aij->a));
62     if (ofree_ij) PetscCall(PetscFree(aij->j));
63     if (ofree_ij) PetscCall(PetscFree(aij->i));
64   }
65   aij->i     = i;
66   aij->j     = j;
67   aij->a     = a;
68   aij->nonew = -1; /* this indicates that inserting a new value in the matrix that generates a new nonzero is an error */
69   /* default to not retain ownership */
70   aij->singlemalloc = PETSC_FALSE;
71   aij->free_a       = PETSC_FALSE;
72   aij->free_ij      = PETSC_FALSE;
73   PetscCall(MatCheckCompressedRow(mat, aij->nonzerorowcnt, &aij->compressedrow, aij->i, m, 0.6));
74   // Always build the diag info when i, j are set
75   PetscCall(MatMarkDiagonal_SeqAIJ(mat));
76   PetscFunctionReturn(PETSC_SUCCESS);
77 }
78 
79 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ(Mat A, Mat B, PetscReal fill, Mat C)
80 {
81   Mat_Product        *product = C->product;
82   MatProductAlgorithm alg;
83   PetscBool           flg;
84 
85   PetscFunctionBegin;
86   if (product) {
87     alg = product->alg;
88   } else {
89     alg = "sorted";
90   }
91   /* sorted */
92   PetscCall(PetscStrcmp(alg, "sorted", &flg));
93   if (flg) {
94     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_Sorted(A, B, fill, C));
95     PetscFunctionReturn(PETSC_SUCCESS);
96   }
97 
98   /* scalable */
99   PetscCall(PetscStrcmp(alg, "scalable", &flg));
100   if (flg) {
101     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_Scalable(A, B, fill, C));
102     PetscFunctionReturn(PETSC_SUCCESS);
103   }
104 
105   /* scalable_fast */
106   PetscCall(PetscStrcmp(alg, "scalable_fast", &flg));
107   if (flg) {
108     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_Scalable_fast(A, B, fill, C));
109     PetscFunctionReturn(PETSC_SUCCESS);
110   }
111 
112   /* heap */
113   PetscCall(PetscStrcmp(alg, "heap", &flg));
114   if (flg) {
115     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_Heap(A, B, fill, C));
116     PetscFunctionReturn(PETSC_SUCCESS);
117   }
118 
119   /* btheap */
120   PetscCall(PetscStrcmp(alg, "btheap", &flg));
121   if (flg) {
122     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_BTHeap(A, B, fill, C));
123     PetscFunctionReturn(PETSC_SUCCESS);
124   }
125 
126   /* llcondensed */
127   PetscCall(PetscStrcmp(alg, "llcondensed", &flg));
128   if (flg) {
129     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_LLCondensed(A, B, fill, C));
130     PetscFunctionReturn(PETSC_SUCCESS);
131   }
132 
133   /* rowmerge */
134   PetscCall(PetscStrcmp(alg, "rowmerge", &flg));
135   if (flg) {
136     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ_RowMerge(A, B, fill, C));
137     PetscFunctionReturn(PETSC_SUCCESS);
138   }
139 
140 #if defined(PETSC_HAVE_HYPRE)
141   PetscCall(PetscStrcmp(alg, "hypre", &flg));
142   if (flg) {
143     PetscCall(MatMatMultSymbolic_AIJ_AIJ_wHYPRE(A, B, fill, C));
144     PetscFunctionReturn(PETSC_SUCCESS);
145   }
146 #endif
147 
148   SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "Mat Product Algorithm is not supported");
149 }
150 
151 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_LLCondensed(Mat A, Mat B, PetscReal fill, Mat C)
152 {
153   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
154   PetscInt          *ai = a->i, *bi = b->i, *ci, *cj;
155   PetscInt           am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
156   PetscReal          afill;
157   PetscInt           i, j, anzi, brow, bnzj, cnzi, *bj, *aj, *lnk, ndouble = 0, Crmax;
158   PetscHMapI         ta;
159   PetscBT            lnkbt;
160   PetscFreeSpaceList free_space = NULL, current_space = NULL;
161 
162   PetscFunctionBegin;
163   /* Get ci and cj */
164   /* Allocate ci array, arrays for fill computation and */
165   /* free space for accumulating nonzero column info */
166   PetscCall(PetscMalloc1(am + 2, &ci));
167   ci[0] = 0;
168 
169   /* create and initialize a linked list */
170   PetscCall(PetscHMapICreateWithSize(bn, &ta));
171   MatRowMergeMax_SeqAIJ(b, bm, ta);
172   PetscCall(PetscHMapIGetSize(ta, &Crmax));
173   PetscCall(PetscHMapIDestroy(&ta));
174 
175   PetscCall(PetscLLCondensedCreate(Crmax, bn, &lnk, &lnkbt));
176 
177   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
178   PetscCall(PetscFreeSpaceGet(PetscRealIntMultTruncate(fill, PetscIntSumTruncate(ai[am], bi[bm])), &free_space));
179 
180   current_space = free_space;
181 
182   /* Determine ci and cj */
183   for (i = 0; i < am; i++) {
184     anzi = ai[i + 1] - ai[i];
185     aj   = a->j + ai[i];
186     for (j = 0; j < anzi; j++) {
187       brow = aj[j];
188       bnzj = bi[brow + 1] - bi[brow];
189       bj   = b->j + bi[brow];
190       /* add non-zero cols of B into the sorted linked list lnk */
191       PetscCall(PetscLLCondensedAddSorted(bnzj, bj, lnk, lnkbt));
192     }
193     /* add possible missing diagonal entry */
194     if (C->force_diagonals) PetscCall(PetscLLCondensedAddSorted(1, &i, lnk, lnkbt));
195     cnzi = lnk[0];
196 
197     /* If free space is not available, make more free space */
198     /* Double the amount of total space in the list */
199     if (current_space->local_remaining < cnzi) {
200       PetscCall(PetscFreeSpaceGet(PetscIntSumTruncate(cnzi, current_space->total_array_size), &current_space));
201       ndouble++;
202     }
203 
204     /* Copy data into free space, then initialize lnk */
205     PetscCall(PetscLLCondensedClean(bn, cnzi, current_space->array, lnk, lnkbt));
206 
207     current_space->array += cnzi;
208     current_space->local_used += cnzi;
209     current_space->local_remaining -= cnzi;
210 
211     ci[i + 1] = ci[i] + cnzi;
212   }
213 
214   /* Column indices are in the list of free space */
215   /* Allocate space for cj, initialize cj, and */
216   /* destroy list of free space and other temporary array(s) */
217   PetscCall(PetscMalloc1(ci[am] + 1, &cj));
218   PetscCall(PetscFreeSpaceContiguous(&free_space, cj));
219   PetscCall(PetscLLCondensedDestroy(lnk, lnkbt));
220 
221   /* put together the new symbolic matrix */
222   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, NULL, ((PetscObject)A)->type_name, C));
223   PetscCall(MatSetBlockSizesFromMats(C, A, B));
224 
225   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
226   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
227   c          = (Mat_SeqAIJ *)C->data;
228   c->free_a  = PETSC_FALSE;
229   c->free_ij = PETSC_TRUE;
230   c->nonew   = 0;
231 
232   /* fast, needs non-scalable O(bn) array 'abdense' */
233   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted;
234 
235   /* set MatInfo */
236   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
237   if (afill < 1.0) afill = 1.0;
238   C->info.mallocs           = ndouble;
239   C->info.fill_ratio_given  = fill;
240   C->info.fill_ratio_needed = afill;
241 
242 #if defined(PETSC_USE_INFO)
243   if (ci[am]) {
244     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
245     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
246   } else {
247     PetscCall(PetscInfo(C, "Empty matrix product\n"));
248   }
249 #endif
250   PetscFunctionReturn(PETSC_SUCCESS);
251 }
252 
253 PetscErrorCode MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted(Mat A, Mat B, Mat C)
254 {
255   PetscLogDouble     flops = 0.0;
256   Mat_SeqAIJ        *a     = (Mat_SeqAIJ *)A->data;
257   Mat_SeqAIJ        *b     = (Mat_SeqAIJ *)B->data;
258   Mat_SeqAIJ        *c     = (Mat_SeqAIJ *)C->data;
259   PetscInt          *ai = a->i, *aj = a->j, *bi = b->i, *bj = b->j, *bjj, *ci = c->i, *cj = c->j;
260   PetscInt           am = A->rmap->n, cm = C->rmap->n;
261   PetscInt           i, j, k, anzi, bnzi, cnzi, brow;
262   PetscScalar       *ca, valtmp;
263   PetscScalar       *ab_dense;
264   PetscContainer     cab_dense;
265   const PetscScalar *aa, *ba, *baj;
266 
267   PetscFunctionBegin;
268   PetscCall(MatSeqAIJGetArrayRead(A, &aa));
269   PetscCall(MatSeqAIJGetArrayRead(B, &ba));
270   if (!c->a) { /* first call of MatMatMultNumeric_SeqAIJ_SeqAIJ, allocate ca and matmult_abdense */
271     PetscCall(PetscMalloc1(ci[cm] + 1, &ca));
272     c->a      = ca;
273     c->free_a = PETSC_TRUE;
274   } else ca = c->a;
275 
276   /* TODO this should be done in the symbolic phase */
277   /* However, this function is so heavily used (sometimes in an hidden way through multnumeric function pointers
278      that is hard to eradicate) */
279   PetscCall(PetscObjectQuery((PetscObject)C, "__PETSc__ab_dense", (PetscObject *)&cab_dense));
280   if (!cab_dense) {
281     PetscCall(PetscMalloc1(B->cmap->N, &ab_dense));
282     PetscCall(PetscContainerCreate(PETSC_COMM_SELF, &cab_dense));
283     PetscCall(PetscContainerSetPointer(cab_dense, ab_dense));
284     PetscCall(PetscContainerSetUserDestroy(cab_dense, PetscContainerUserDestroyDefault));
285     PetscCall(PetscObjectCompose((PetscObject)C, "__PETSc__ab_dense", (PetscObject)cab_dense));
286     PetscCall(PetscObjectDereference((PetscObject)cab_dense));
287   }
288   PetscCall(PetscContainerGetPointer(cab_dense, (void **)&ab_dense));
289   PetscCall(PetscArrayzero(ab_dense, B->cmap->N));
290 
291   /* clean old values in C */
292   PetscCall(PetscArrayzero(ca, ci[cm]));
293   /* Traverse A row-wise. */
294   /* Build the ith row in C by summing over nonzero columns in A, */
295   /* the rows of B corresponding to nonzeros of A. */
296   for (i = 0; i < am; i++) {
297     anzi = ai[i + 1] - ai[i];
298     for (j = 0; j < anzi; j++) {
299       brow = aj[j];
300       bnzi = bi[brow + 1] - bi[brow];
301       bjj  = PetscSafePointerPlusOffset(bj, bi[brow]);
302       baj  = PetscSafePointerPlusOffset(ba, bi[brow]);
303       /* perform dense axpy */
304       valtmp = aa[j];
305       for (k = 0; k < bnzi; k++) ab_dense[bjj[k]] += valtmp * baj[k];
306       flops += 2 * bnzi;
307     }
308     aj = PetscSafePointerPlusOffset(aj, anzi);
309     aa = PetscSafePointerPlusOffset(aa, anzi);
310 
311     cnzi = ci[i + 1] - ci[i];
312     for (k = 0; k < cnzi; k++) {
313       ca[k] += ab_dense[cj[k]];
314       ab_dense[cj[k]] = 0.0; /* zero ab_dense */
315     }
316     flops += cnzi;
317     cj = PetscSafePointerPlusOffset(cj, cnzi);
318     ca += cnzi;
319   }
320 #if defined(PETSC_HAVE_DEVICE)
321   if (C->offloadmask != PETSC_OFFLOAD_UNALLOCATED) C->offloadmask = PETSC_OFFLOAD_CPU;
322 #endif
323   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
324   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
325   PetscCall(PetscLogFlops(flops));
326   PetscCall(MatSeqAIJRestoreArrayRead(A, &aa));
327   PetscCall(MatSeqAIJRestoreArrayRead(B, &ba));
328   PetscFunctionReturn(PETSC_SUCCESS);
329 }
330 
331 PetscErrorCode MatMatMultNumeric_SeqAIJ_SeqAIJ_Scalable(Mat A, Mat B, Mat C)
332 {
333   PetscLogDouble     flops = 0.0;
334   Mat_SeqAIJ        *a     = (Mat_SeqAIJ *)A->data;
335   Mat_SeqAIJ        *b     = (Mat_SeqAIJ *)B->data;
336   Mat_SeqAIJ        *c     = (Mat_SeqAIJ *)C->data;
337   PetscInt          *ai = a->i, *aj = a->j, *bi = b->i, *bj = b->j, *bjj, *ci = c->i, *cj = c->j;
338   PetscInt           am = A->rmap->N, cm = C->rmap->N;
339   PetscInt           i, j, k, anzi, bnzi, cnzi, brow;
340   PetscScalar       *ca = c->a, valtmp;
341   const PetscScalar *aa, *ba, *baj;
342   PetscInt           nextb;
343 
344   PetscFunctionBegin;
345   PetscCall(MatSeqAIJGetArrayRead(A, &aa));
346   PetscCall(MatSeqAIJGetArrayRead(B, &ba));
347   if (!ca) { /* first call of MatMatMultNumeric_SeqAIJ_SeqAIJ, allocate ca and matmult_abdense */
348     PetscCall(PetscMalloc1(ci[cm] + 1, &ca));
349     c->a      = ca;
350     c->free_a = PETSC_TRUE;
351   }
352 
353   /* clean old values in C */
354   PetscCall(PetscArrayzero(ca, ci[cm]));
355   /* Traverse A row-wise. */
356   /* Build the ith row in C by summing over nonzero columns in A, */
357   /* the rows of B corresponding to nonzeros of A. */
358   for (i = 0; i < am; i++) {
359     anzi = ai[i + 1] - ai[i];
360     cnzi = ci[i + 1] - ci[i];
361     for (j = 0; j < anzi; j++) {
362       brow = aj[j];
363       bnzi = bi[brow + 1] - bi[brow];
364       bjj  = bj + bi[brow];
365       baj  = ba + bi[brow];
366       /* perform sparse axpy */
367       valtmp = aa[j];
368       nextb  = 0;
369       for (k = 0; nextb < bnzi; k++) {
370         if (cj[k] == bjj[nextb]) { /* ccol == bcol */
371           ca[k] += valtmp * baj[nextb++];
372         }
373       }
374       flops += 2 * bnzi;
375     }
376     aj += anzi;
377     aa += anzi;
378     cj += cnzi;
379     ca += cnzi;
380   }
381 #if defined(PETSC_HAVE_DEVICE)
382   if (C->offloadmask != PETSC_OFFLOAD_UNALLOCATED) C->offloadmask = PETSC_OFFLOAD_CPU;
383 #endif
384   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
385   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
386   PetscCall(PetscLogFlops(flops));
387   PetscCall(MatSeqAIJRestoreArrayRead(A, &aa));
388   PetscCall(MatSeqAIJRestoreArrayRead(B, &ba));
389   PetscFunctionReturn(PETSC_SUCCESS);
390 }
391 
392 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_Scalable_fast(Mat A, Mat B, PetscReal fill, Mat C)
393 {
394   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
395   PetscInt          *ai = a->i, *bi = b->i, *ci, *cj;
396   PetscInt           am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
397   MatScalar         *ca;
398   PetscReal          afill;
399   PetscInt           i, j, anzi, brow, bnzj, cnzi, *bj, *aj, *lnk, ndouble = 0, Crmax;
400   PetscHMapI         ta;
401   PetscFreeSpaceList free_space = NULL, current_space = NULL;
402 
403   PetscFunctionBegin;
404   /* Get ci and cj - same as MatMatMultSymbolic_SeqAIJ_SeqAIJ except using PetscLLxxx_fast() */
405   /* Allocate arrays for fill computation and free space for accumulating nonzero column */
406   PetscCall(PetscMalloc1(am + 2, &ci));
407   ci[0] = 0;
408 
409   /* create and initialize a linked list */
410   PetscCall(PetscHMapICreateWithSize(bn, &ta));
411   MatRowMergeMax_SeqAIJ(b, bm, ta);
412   PetscCall(PetscHMapIGetSize(ta, &Crmax));
413   PetscCall(PetscHMapIDestroy(&ta));
414 
415   PetscCall(PetscLLCondensedCreate_fast(Crmax, &lnk));
416 
417   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
418   PetscCall(PetscFreeSpaceGet(PetscRealIntMultTruncate(fill, PetscIntSumTruncate(ai[am], bi[bm])), &free_space));
419   current_space = free_space;
420 
421   /* Determine ci and cj */
422   for (i = 0; i < am; i++) {
423     anzi = ai[i + 1] - ai[i];
424     aj   = a->j + ai[i];
425     for (j = 0; j < anzi; j++) {
426       brow = aj[j];
427       bnzj = bi[brow + 1] - bi[brow];
428       bj   = b->j + bi[brow];
429       /* add non-zero cols of B into the sorted linked list lnk */
430       PetscCall(PetscLLCondensedAddSorted_fast(bnzj, bj, lnk));
431     }
432     /* add possible missing diagonal entry */
433     if (C->force_diagonals) PetscCall(PetscLLCondensedAddSorted_fast(1, &i, lnk));
434     cnzi = lnk[1];
435 
436     /* If free space is not available, make more free space */
437     /* Double the amount of total space in the list */
438     if (current_space->local_remaining < cnzi) {
439       PetscCall(PetscFreeSpaceGet(PetscIntSumTruncate(cnzi, current_space->total_array_size), &current_space));
440       ndouble++;
441     }
442 
443     /* Copy data into free space, then initialize lnk */
444     PetscCall(PetscLLCondensedClean_fast(cnzi, current_space->array, lnk));
445 
446     current_space->array += cnzi;
447     current_space->local_used += cnzi;
448     current_space->local_remaining -= cnzi;
449 
450     ci[i + 1] = ci[i] + cnzi;
451   }
452 
453   /* Column indices are in the list of free space */
454   /* Allocate space for cj, initialize cj, and */
455   /* destroy list of free space and other temporary array(s) */
456   PetscCall(PetscMalloc1(ci[am] + 1, &cj));
457   PetscCall(PetscFreeSpaceContiguous(&free_space, cj));
458   PetscCall(PetscLLCondensedDestroy_fast(lnk));
459 
460   /* Allocate space for ca */
461   PetscCall(PetscCalloc1(ci[am] + 1, &ca));
462 
463   /* put together the new symbolic matrix */
464   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, ca, ((PetscObject)A)->type_name, C));
465   PetscCall(MatSetBlockSizesFromMats(C, A, B));
466 
467   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
468   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
469   c          = (Mat_SeqAIJ *)C->data;
470   c->free_a  = PETSC_TRUE;
471   c->free_ij = PETSC_TRUE;
472   c->nonew   = 0;
473 
474   /* slower, less memory */
475   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Scalable;
476 
477   /* set MatInfo */
478   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
479   if (afill < 1.0) afill = 1.0;
480   C->info.mallocs           = ndouble;
481   C->info.fill_ratio_given  = fill;
482   C->info.fill_ratio_needed = afill;
483 
484 #if defined(PETSC_USE_INFO)
485   if (ci[am]) {
486     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
487     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
488   } else {
489     PetscCall(PetscInfo(C, "Empty matrix product\n"));
490   }
491 #endif
492   PetscFunctionReturn(PETSC_SUCCESS);
493 }
494 
495 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_Scalable(Mat A, Mat B, PetscReal fill, Mat C)
496 {
497   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
498   PetscInt          *ai = a->i, *bi = b->i, *ci, *cj;
499   PetscInt           am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
500   MatScalar         *ca;
501   PetscReal          afill;
502   PetscInt           i, j, anzi, brow, bnzj, cnzi, *bj, *aj, *lnk, ndouble = 0, Crmax;
503   PetscHMapI         ta;
504   PetscFreeSpaceList free_space = NULL, current_space = NULL;
505 
506   PetscFunctionBegin;
507   /* Get ci and cj - same as MatMatMultSymbolic_SeqAIJ_SeqAIJ except using PetscLLxxx_Scalalbe() */
508   /* Allocate arrays for fill computation and free space for accumulating nonzero column */
509   PetscCall(PetscMalloc1(am + 2, &ci));
510   ci[0] = 0;
511 
512   /* create and initialize a linked list */
513   PetscCall(PetscHMapICreateWithSize(bn, &ta));
514   MatRowMergeMax_SeqAIJ(b, bm, ta);
515   PetscCall(PetscHMapIGetSize(ta, &Crmax));
516   PetscCall(PetscHMapIDestroy(&ta));
517   PetscCall(PetscLLCondensedCreate_Scalable(Crmax, &lnk));
518 
519   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
520   PetscCall(PetscFreeSpaceGet(PetscRealIntMultTruncate(fill, PetscIntSumTruncate(ai[am], bi[bm])), &free_space));
521   current_space = free_space;
522 
523   /* Determine ci and cj */
524   for (i = 0; i < am; i++) {
525     anzi = ai[i + 1] - ai[i];
526     aj   = a->j + ai[i];
527     for (j = 0; j < anzi; j++) {
528       brow = aj[j];
529       bnzj = bi[brow + 1] - bi[brow];
530       bj   = b->j + bi[brow];
531       /* add non-zero cols of B into the sorted linked list lnk */
532       PetscCall(PetscLLCondensedAddSorted_Scalable(bnzj, bj, lnk));
533     }
534     /* add possible missing diagonal entry */
535     if (C->force_diagonals) PetscCall(PetscLLCondensedAddSorted_Scalable(1, &i, lnk));
536 
537     cnzi = lnk[0];
538 
539     /* If free space is not available, make more free space */
540     /* Double the amount of total space in the list */
541     if (current_space->local_remaining < cnzi) {
542       PetscCall(PetscFreeSpaceGet(PetscIntSumTruncate(cnzi, current_space->total_array_size), &current_space));
543       ndouble++;
544     }
545 
546     /* Copy data into free space, then initialize lnk */
547     PetscCall(PetscLLCondensedClean_Scalable(cnzi, current_space->array, lnk));
548 
549     current_space->array += cnzi;
550     current_space->local_used += cnzi;
551     current_space->local_remaining -= cnzi;
552 
553     ci[i + 1] = ci[i] + cnzi;
554   }
555 
556   /* Column indices are in the list of free space */
557   /* Allocate space for cj, initialize cj, and */
558   /* destroy list of free space and other temporary array(s) */
559   PetscCall(PetscMalloc1(ci[am] + 1, &cj));
560   PetscCall(PetscFreeSpaceContiguous(&free_space, cj));
561   PetscCall(PetscLLCondensedDestroy_Scalable(lnk));
562 
563   /* Allocate space for ca */
564   PetscCall(PetscCalloc1(ci[am] + 1, &ca));
565 
566   /* put together the new symbolic matrix */
567   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, ca, ((PetscObject)A)->type_name, C));
568   PetscCall(MatSetBlockSizesFromMats(C, A, B));
569 
570   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
571   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
572   c          = (Mat_SeqAIJ *)C->data;
573   c->free_a  = PETSC_TRUE;
574   c->free_ij = PETSC_TRUE;
575   c->nonew   = 0;
576 
577   /* slower, less memory */
578   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Scalable;
579 
580   /* set MatInfo */
581   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
582   if (afill < 1.0) afill = 1.0;
583   C->info.mallocs           = ndouble;
584   C->info.fill_ratio_given  = fill;
585   C->info.fill_ratio_needed = afill;
586 
587 #if defined(PETSC_USE_INFO)
588   if (ci[am]) {
589     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
590     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
591   } else {
592     PetscCall(PetscInfo(C, "Empty matrix product\n"));
593   }
594 #endif
595   PetscFunctionReturn(PETSC_SUCCESS);
596 }
597 
598 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_Heap(Mat A, Mat B, PetscReal fill, Mat C)
599 {
600   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
601   const PetscInt    *ai = a->i, *bi = b->i, *aj = a->j, *bj = b->j;
602   PetscInt          *ci, *cj, *bb;
603   PetscInt           am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
604   PetscReal          afill;
605   PetscInt           i, j, col, ndouble = 0;
606   PetscFreeSpaceList free_space = NULL, current_space = NULL;
607   PetscHeap          h;
608 
609   PetscFunctionBegin;
610   /* Get ci and cj - by merging sorted rows using a heap */
611   /* Allocate arrays for fill computation and free space for accumulating nonzero column */
612   PetscCall(PetscMalloc1(am + 2, &ci));
613   ci[0] = 0;
614 
615   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
616   PetscCall(PetscFreeSpaceGet(PetscRealIntMultTruncate(fill, PetscIntSumTruncate(ai[am], bi[bm])), &free_space));
617   current_space = free_space;
618 
619   PetscCall(PetscHeapCreate(a->rmax, &h));
620   PetscCall(PetscMalloc1(a->rmax, &bb));
621 
622   /* Determine ci and cj */
623   for (i = 0; i < am; i++) {
624     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 */
625     const PetscInt *acol = aj + ai[i];        /* column indices of nonzero entries in this row */
626     ci[i + 1]            = ci[i];
627     /* Populate the min heap */
628     for (j = 0; j < anzi; j++) {
629       bb[j] = bi[acol[j]];           /* bb points at the start of the row */
630       if (bb[j] < bi[acol[j] + 1]) { /* Add if row is nonempty */
631         PetscCall(PetscHeapAdd(h, j, bj[bb[j]++]));
632       }
633     }
634     /* Pick off the min element, adding it to free space */
635     PetscCall(PetscHeapPop(h, &j, &col));
636     while (j >= 0) {
637       if (current_space->local_remaining < 1) { /* double the size, but don't exceed 16 MiB */
638         PetscCall(PetscFreeSpaceGet(PetscMin(PetscIntMultTruncate(2, current_space->total_array_size), 16 << 20), &current_space));
639         ndouble++;
640       }
641       *(current_space->array++) = col;
642       current_space->local_used++;
643       current_space->local_remaining--;
644       ci[i + 1]++;
645 
646       /* stash if anything else remains in this row of B */
647       if (bb[j] < bi[acol[j] + 1]) PetscCall(PetscHeapStash(h, j, bj[bb[j]++]));
648       while (1) { /* pop and stash any other rows of B that also had an entry in this column */
649         PetscInt j2, col2;
650         PetscCall(PetscHeapPeek(h, &j2, &col2));
651         if (col2 != col) break;
652         PetscCall(PetscHeapPop(h, &j2, &col2));
653         if (bb[j2] < bi[acol[j2] + 1]) PetscCall(PetscHeapStash(h, j2, bj[bb[j2]++]));
654       }
655       /* Put any stashed elements back into the min heap */
656       PetscCall(PetscHeapUnstash(h));
657       PetscCall(PetscHeapPop(h, &j, &col));
658     }
659   }
660   PetscCall(PetscFree(bb));
661   PetscCall(PetscHeapDestroy(&h));
662 
663   /* Column indices are in the list of free space */
664   /* Allocate space for cj, initialize cj, and */
665   /* destroy list of free space and other temporary array(s) */
666   PetscCall(PetscMalloc1(ci[am], &cj));
667   PetscCall(PetscFreeSpaceContiguous(&free_space, cj));
668 
669   /* put together the new symbolic matrix */
670   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, NULL, ((PetscObject)A)->type_name, C));
671   PetscCall(MatSetBlockSizesFromMats(C, A, B));
672 
673   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
674   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
675   c          = (Mat_SeqAIJ *)C->data;
676   c->free_a  = PETSC_TRUE;
677   c->free_ij = PETSC_TRUE;
678   c->nonew   = 0;
679 
680   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted;
681 
682   /* set MatInfo */
683   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
684   if (afill < 1.0) afill = 1.0;
685   C->info.mallocs           = ndouble;
686   C->info.fill_ratio_given  = fill;
687   C->info.fill_ratio_needed = afill;
688 
689 #if defined(PETSC_USE_INFO)
690   if (ci[am]) {
691     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
692     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
693   } else {
694     PetscCall(PetscInfo(C, "Empty matrix product\n"));
695   }
696 #endif
697   PetscFunctionReturn(PETSC_SUCCESS);
698 }
699 
700 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_BTHeap(Mat A, Mat B, PetscReal fill, Mat C)
701 {
702   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
703   const PetscInt    *ai = a->i, *bi = b->i, *aj = a->j, *bj = b->j;
704   PetscInt          *ci, *cj, *bb;
705   PetscInt           am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
706   PetscReal          afill;
707   PetscInt           i, j, col, ndouble = 0;
708   PetscFreeSpaceList free_space = NULL, current_space = NULL;
709   PetscHeap          h;
710   PetscBT            bt;
711 
712   PetscFunctionBegin;
713   /* Get ci and cj - using a heap for the sorted rows, but use BT so that each index is only added once */
714   /* Allocate arrays for fill computation and free space for accumulating nonzero column */
715   PetscCall(PetscMalloc1(am + 2, &ci));
716   ci[0] = 0;
717 
718   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
719   PetscCall(PetscFreeSpaceGet(PetscRealIntMultTruncate(fill, PetscIntSumTruncate(ai[am], bi[bm])), &free_space));
720 
721   current_space = free_space;
722 
723   PetscCall(PetscHeapCreate(a->rmax, &h));
724   PetscCall(PetscMalloc1(a->rmax, &bb));
725   PetscCall(PetscBTCreate(bn, &bt));
726 
727   /* Determine ci and cj */
728   for (i = 0; i < am; i++) {
729     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 */
730     const PetscInt *acol = aj + ai[i];           /* column indices of nonzero entries in this row */
731     const PetscInt *fptr = current_space->array; /* Save beginning of the row so we can clear the BT later */
732     ci[i + 1]            = ci[i];
733     /* Populate the min heap */
734     for (j = 0; j < anzi; j++) {
735       PetscInt brow = acol[j];
736       for (bb[j] = bi[brow]; bb[j] < bi[brow + 1]; bb[j]++) {
737         PetscInt bcol = bj[bb[j]];
738         if (!PetscBTLookupSet(bt, bcol)) { /* new entry */
739           PetscCall(PetscHeapAdd(h, j, bcol));
740           bb[j]++;
741           break;
742         }
743       }
744     }
745     /* Pick off the min element, adding it to free space */
746     PetscCall(PetscHeapPop(h, &j, &col));
747     while (j >= 0) {
748       if (current_space->local_remaining < 1) { /* double the size, but don't exceed 16 MiB */
749         fptr = NULL;                            /* need PetscBTMemzero */
750         PetscCall(PetscFreeSpaceGet(PetscMin(PetscIntMultTruncate(2, current_space->total_array_size), 16 << 20), &current_space));
751         ndouble++;
752       }
753       *(current_space->array++) = col;
754       current_space->local_used++;
755       current_space->local_remaining--;
756       ci[i + 1]++;
757 
758       /* stash if anything else remains in this row of B */
759       for (; bb[j] < bi[acol[j] + 1]; bb[j]++) {
760         PetscInt bcol = bj[bb[j]];
761         if (!PetscBTLookupSet(bt, bcol)) { /* new entry */
762           PetscCall(PetscHeapAdd(h, j, bcol));
763           bb[j]++;
764           break;
765         }
766       }
767       PetscCall(PetscHeapPop(h, &j, &col));
768     }
769     if (fptr) { /* Clear the bits for this row */
770       for (; fptr < current_space->array; fptr++) PetscCall(PetscBTClear(bt, *fptr));
771     } else { /* We reallocated so we don't remember (easily) how to clear only the bits we changed */
772       PetscCall(PetscBTMemzero(bn, bt));
773     }
774   }
775   PetscCall(PetscFree(bb));
776   PetscCall(PetscHeapDestroy(&h));
777   PetscCall(PetscBTDestroy(&bt));
778 
779   /* Column indices are in the list of free space */
780   /* Allocate space for cj, initialize cj, and */
781   /* destroy list of free space and other temporary array(s) */
782   PetscCall(PetscMalloc1(ci[am], &cj));
783   PetscCall(PetscFreeSpaceContiguous(&free_space, cj));
784 
785   /* put together the new symbolic matrix */
786   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, NULL, ((PetscObject)A)->type_name, C));
787   PetscCall(MatSetBlockSizesFromMats(C, A, B));
788 
789   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
790   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
791   c          = (Mat_SeqAIJ *)C->data;
792   c->free_a  = PETSC_TRUE;
793   c->free_ij = PETSC_TRUE;
794   c->nonew   = 0;
795 
796   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted;
797 
798   /* set MatInfo */
799   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
800   if (afill < 1.0) afill = 1.0;
801   C->info.mallocs           = ndouble;
802   C->info.fill_ratio_given  = fill;
803   C->info.fill_ratio_needed = afill;
804 
805 #if defined(PETSC_USE_INFO)
806   if (ci[am]) {
807     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
808     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
809   } else {
810     PetscCall(PetscInfo(C, "Empty matrix product\n"));
811   }
812 #endif
813   PetscFunctionReturn(PETSC_SUCCESS);
814 }
815 
816 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_RowMerge(Mat A, Mat B, PetscReal fill, Mat C)
817 {
818   Mat_SeqAIJ     *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
819   const PetscInt *ai = a->i, *bi = b->i, *aj = a->j, *bj = b->j, *inputi, *inputj, *inputcol, *inputcol_L1;
820   PetscInt       *ci, *cj, *outputj, worki_L1[9], worki_L2[9];
821   PetscInt        c_maxmem, a_maxrownnz = 0, a_rownnz;
822   const PetscInt  workcol[8] = {0, 1, 2, 3, 4, 5, 6, 7};
823   const PetscInt  am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
824   const PetscInt *brow_ptr[8], *brow_end[8];
825   PetscInt        window[8];
826   PetscInt        window_min, old_window_min, ci_nnz, outputi_nnz = 0, L1_nrows, L2_nrows;
827   PetscInt        i, k, ndouble = 0, L1_rowsleft, rowsleft;
828   PetscReal       afill;
829   PetscInt       *workj_L1, *workj_L2, *workj_L3;
830   PetscInt        L1_nnz, L2_nnz;
831 
832   /* Step 1: Get upper bound on memory required for allocation.
833              Because of the way virtual memory works,
834              only the memory pages that are actually needed will be physically allocated. */
835   PetscFunctionBegin;
836   PetscCall(PetscMalloc1(am + 1, &ci));
837   for (i = 0; i < am; i++) {
838     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 */
839     const PetscInt *acol = aj + ai[i];        /* column indices of nonzero entries in this row */
840     a_rownnz             = 0;
841     for (k = 0; k < anzi; ++k) {
842       a_rownnz += bi[acol[k] + 1] - bi[acol[k]];
843       if (a_rownnz > bn) {
844         a_rownnz = bn;
845         break;
846       }
847     }
848     a_maxrownnz = PetscMax(a_maxrownnz, a_rownnz);
849   }
850   /* temporary work areas for merging rows */
851   PetscCall(PetscMalloc1(a_maxrownnz * 8, &workj_L1));
852   PetscCall(PetscMalloc1(a_maxrownnz * 8, &workj_L2));
853   PetscCall(PetscMalloc1(a_maxrownnz, &workj_L3));
854 
855   /* This should be enough for almost all matrices. If not, memory is reallocated later. */
856   c_maxmem = 8 * (ai[am] + bi[bm]);
857   /* Step 2: Populate pattern for C */
858   PetscCall(PetscMalloc1(c_maxmem, &cj));
859 
860   ci_nnz      = 0;
861   ci[0]       = 0;
862   worki_L1[0] = 0;
863   worki_L2[0] = 0;
864   for (i = 0; i < am; i++) {
865     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 */
866     const PetscInt *acol = aj + ai[i];        /* column indices of nonzero entries in this row */
867     rowsleft             = anzi;
868     inputcol_L1          = acol;
869     L2_nnz               = 0;
870     L2_nrows             = 1; /* Number of rows to be merged on Level 3. output of L3 already exists -> initial value 1   */
871     worki_L2[1]          = 0;
872     outputi_nnz          = 0;
873 
874     /* If the number of indices in C so far + the max number of columns in the next row > c_maxmem  -> allocate more memory */
875     while (ci_nnz + a_maxrownnz > c_maxmem) {
876       c_maxmem *= 2;
877       ndouble++;
878       PetscCall(PetscRealloc(sizeof(PetscInt) * c_maxmem, &cj));
879     }
880 
881     while (rowsleft) {
882       L1_rowsleft = PetscMin(64, rowsleft); /* In the inner loop max 64 rows of B can be merged */
883       L1_nrows    = 0;
884       L1_nnz      = 0;
885       inputcol    = inputcol_L1;
886       inputi      = bi;
887       inputj      = bj;
888 
889       /* The following macro is used to specialize for small rows in A.
890          This helps with compiler unrolling, improving performance substantially.
891           Input:  inputj   inputi  inputcol  bn
892           Output: outputj  outputi_nnz                       */
893 #define MatMatMultSymbolic_RowMergeMacro(ANNZ) \
894   do { \
895     window_min  = bn; \
896     outputi_nnz = 0; \
897     for (k = 0; k < ANNZ; ++k) { \
898       brow_ptr[k] = inputj + inputi[inputcol[k]]; \
899       brow_end[k] = inputj + inputi[inputcol[k] + 1]; \
900       window[k]   = (brow_ptr[k] != brow_end[k]) ? *brow_ptr[k] : bn; \
901       window_min  = PetscMin(window[k], window_min); \
902     } \
903     while (window_min < bn) { \
904       outputj[outputi_nnz++] = window_min; \
905       /* advance front and compute new minimum */ \
906       old_window_min = window_min; \
907       window_min     = bn; \
908       for (k = 0; k < ANNZ; ++k) { \
909         if (window[k] == old_window_min) { \
910           brow_ptr[k]++; \
911           window[k] = (brow_ptr[k] != brow_end[k]) ? *brow_ptr[k] : bn; \
912         } \
913         window_min = PetscMin(window[k], window_min); \
914       } \
915     } \
916   } while (0)
917 
918       /************** L E V E L  1 ***************/
919       /* Merge up to 8 rows of B to L1 work array*/
920       while (L1_rowsleft) {
921         outputi_nnz = 0;
922         if (anzi > 8) outputj = workj_L1 + L1_nnz; /* Level 1 rowmerge*/
923         else outputj = cj + ci_nnz;                /* Merge directly to C */
924 
925         switch (L1_rowsleft) {
926         case 1:
927           brow_ptr[0] = inputj + inputi[inputcol[0]];
928           brow_end[0] = inputj + inputi[inputcol[0] + 1];
929           for (; brow_ptr[0] != brow_end[0]; ++brow_ptr[0]) outputj[outputi_nnz++] = *brow_ptr[0]; /* copy row in b over */
930           inputcol += L1_rowsleft;
931           rowsleft -= L1_rowsleft;
932           L1_rowsleft = 0;
933           break;
934         case 2:
935           MatMatMultSymbolic_RowMergeMacro(2);
936           inputcol += L1_rowsleft;
937           rowsleft -= L1_rowsleft;
938           L1_rowsleft = 0;
939           break;
940         case 3:
941           MatMatMultSymbolic_RowMergeMacro(3);
942           inputcol += L1_rowsleft;
943           rowsleft -= L1_rowsleft;
944           L1_rowsleft = 0;
945           break;
946         case 4:
947           MatMatMultSymbolic_RowMergeMacro(4);
948           inputcol += L1_rowsleft;
949           rowsleft -= L1_rowsleft;
950           L1_rowsleft = 0;
951           break;
952         case 5:
953           MatMatMultSymbolic_RowMergeMacro(5);
954           inputcol += L1_rowsleft;
955           rowsleft -= L1_rowsleft;
956           L1_rowsleft = 0;
957           break;
958         case 6:
959           MatMatMultSymbolic_RowMergeMacro(6);
960           inputcol += L1_rowsleft;
961           rowsleft -= L1_rowsleft;
962           L1_rowsleft = 0;
963           break;
964         case 7:
965           MatMatMultSymbolic_RowMergeMacro(7);
966           inputcol += L1_rowsleft;
967           rowsleft -= L1_rowsleft;
968           L1_rowsleft = 0;
969           break;
970         default:
971           MatMatMultSymbolic_RowMergeMacro(8);
972           inputcol += 8;
973           rowsleft -= 8;
974           L1_rowsleft -= 8;
975           break;
976         }
977         inputcol_L1 = inputcol;
978         L1_nnz += outputi_nnz;
979         worki_L1[++L1_nrows] = L1_nnz;
980       }
981 
982       /********************** L E V E L  2 ************************/
983       /* Merge from L1 work array to either C or to L2 work array */
984       if (anzi > 8) {
985         inputi      = worki_L1;
986         inputj      = workj_L1;
987         inputcol    = workcol;
988         outputi_nnz = 0;
989 
990         if (anzi <= 64) outputj = cj + ci_nnz; /* Merge from L1 work array to C */
991         else outputj = workj_L2 + L2_nnz;      /* Merge from L1 work array to L2 work array */
992 
993         switch (L1_nrows) {
994         case 1:
995           brow_ptr[0] = inputj + inputi[inputcol[0]];
996           brow_end[0] = inputj + inputi[inputcol[0] + 1];
997           for (; brow_ptr[0] != brow_end[0]; ++brow_ptr[0]) outputj[outputi_nnz++] = *brow_ptr[0]; /* copy row in b over */
998           break;
999         case 2:
1000           MatMatMultSymbolic_RowMergeMacro(2);
1001           break;
1002         case 3:
1003           MatMatMultSymbolic_RowMergeMacro(3);
1004           break;
1005         case 4:
1006           MatMatMultSymbolic_RowMergeMacro(4);
1007           break;
1008         case 5:
1009           MatMatMultSymbolic_RowMergeMacro(5);
1010           break;
1011         case 6:
1012           MatMatMultSymbolic_RowMergeMacro(6);
1013           break;
1014         case 7:
1015           MatMatMultSymbolic_RowMergeMacro(7);
1016           break;
1017         case 8:
1018           MatMatMultSymbolic_RowMergeMacro(8);
1019           break;
1020         default:
1021           SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "MatMatMult logic error: Not merging 1-8 rows from L1 work array!");
1022         }
1023         L2_nnz += outputi_nnz;
1024         worki_L2[++L2_nrows] = L2_nnz;
1025 
1026         /************************ L E V E L  3 **********************/
1027         /* Merge from L2 work array to either C or to L2 work array */
1028         if (anzi > 64 && (L2_nrows == 8 || rowsleft == 0)) {
1029           inputi      = worki_L2;
1030           inputj      = workj_L2;
1031           inputcol    = workcol;
1032           outputi_nnz = 0;
1033           if (rowsleft) outputj = workj_L3;
1034           else outputj = cj + ci_nnz;
1035           switch (L2_nrows) {
1036           case 1:
1037             brow_ptr[0] = inputj + inputi[inputcol[0]];
1038             brow_end[0] = inputj + inputi[inputcol[0] + 1];
1039             for (; brow_ptr[0] != brow_end[0]; ++brow_ptr[0]) outputj[outputi_nnz++] = *brow_ptr[0]; /* copy row in b over */
1040             break;
1041           case 2:
1042             MatMatMultSymbolic_RowMergeMacro(2);
1043             break;
1044           case 3:
1045             MatMatMultSymbolic_RowMergeMacro(3);
1046             break;
1047           case 4:
1048             MatMatMultSymbolic_RowMergeMacro(4);
1049             break;
1050           case 5:
1051             MatMatMultSymbolic_RowMergeMacro(5);
1052             break;
1053           case 6:
1054             MatMatMultSymbolic_RowMergeMacro(6);
1055             break;
1056           case 7:
1057             MatMatMultSymbolic_RowMergeMacro(7);
1058             break;
1059           case 8:
1060             MatMatMultSymbolic_RowMergeMacro(8);
1061             break;
1062           default:
1063             SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "MatMatMult logic error: Not merging 1-8 rows from L2 work array!");
1064           }
1065           L2_nrows    = 1;
1066           L2_nnz      = outputi_nnz;
1067           worki_L2[1] = outputi_nnz;
1068           /* Copy to workj_L2 */
1069           if (rowsleft) {
1070             for (k = 0; k < outputi_nnz; ++k) workj_L2[k] = outputj[k];
1071           }
1072         }
1073       }
1074     } /* while (rowsleft) */
1075 #undef MatMatMultSymbolic_RowMergeMacro
1076 
1077     /* terminate current row */
1078     ci_nnz += outputi_nnz;
1079     ci[i + 1] = ci_nnz;
1080   }
1081 
1082   /* Step 3: Create the new symbolic matrix */
1083   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, NULL, ((PetscObject)A)->type_name, C));
1084   PetscCall(MatSetBlockSizesFromMats(C, A, B));
1085 
1086   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
1087   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
1088   c          = (Mat_SeqAIJ *)C->data;
1089   c->free_a  = PETSC_TRUE;
1090   c->free_ij = PETSC_TRUE;
1091   c->nonew   = 0;
1092 
1093   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted;
1094 
1095   /* set MatInfo */
1096   afill = (PetscReal)ci[am] / (ai[am] + bi[bm]) + 1.e-5;
1097   if (afill < 1.0) afill = 1.0;
1098   C->info.mallocs           = ndouble;
1099   C->info.fill_ratio_given  = fill;
1100   C->info.fill_ratio_needed = afill;
1101 
1102 #if defined(PETSC_USE_INFO)
1103   if (ci[am]) {
1104     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
1105     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
1106   } else {
1107     PetscCall(PetscInfo(C, "Empty matrix product\n"));
1108   }
1109 #endif
1110 
1111   /* Step 4: Free temporary work areas */
1112   PetscCall(PetscFree(workj_L1));
1113   PetscCall(PetscFree(workj_L2));
1114   PetscCall(PetscFree(workj_L3));
1115   PetscFunctionReturn(PETSC_SUCCESS);
1116 }
1117 
1118 /* concatenate unique entries and then sort */
1119 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqAIJ_Sorted(Mat A, Mat B, PetscReal fill, Mat C)
1120 {
1121   Mat_SeqAIJ     *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c;
1122   const PetscInt *ai = a->i, *bi = b->i, *aj = a->j, *bj = b->j;
1123   PetscInt       *ci, *cj, bcol;
1124   PetscInt        am = A->rmap->N, bn = B->cmap->N, bm = B->rmap->N;
1125   PetscReal       afill;
1126   PetscInt        i, j, ndouble = 0;
1127   PetscSegBuffer  seg, segrow;
1128   char           *seen;
1129 
1130   PetscFunctionBegin;
1131   PetscCall(PetscMalloc1(am + 1, &ci));
1132   ci[0] = 0;
1133 
1134   /* Initial FreeSpace size is fill*(nnz(A)+nnz(B)) */
1135   PetscCall(PetscSegBufferCreate(sizeof(PetscInt), (PetscInt)(fill * (ai[am] + bi[bm])), &seg));
1136   PetscCall(PetscSegBufferCreate(sizeof(PetscInt), 100, &segrow));
1137   PetscCall(PetscCalloc1(bn, &seen));
1138 
1139   /* Determine ci and cj */
1140   for (i = 0; i < am; i++) {
1141     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 */
1142     const PetscInt *acol = PetscSafePointerPlusOffset(aj, ai[i]); /* column indices of nonzero entries in this row */
1143     PetscInt packlen     = 0, *PETSC_RESTRICT crow;
1144 
1145     /* Pack segrow */
1146     for (j = 0; j < anzi; j++) {
1147       PetscInt brow = acol[j], bjstart = bi[brow], bjend = bi[brow + 1], k;
1148       for (k = bjstart; k < bjend; k++) {
1149         bcol = bj[k];
1150         if (!seen[bcol]) { /* new entry */
1151           PetscInt *PETSC_RESTRICT slot;
1152           PetscCall(PetscSegBufferGetInts(segrow, 1, &slot));
1153           *slot      = bcol;
1154           seen[bcol] = 1;
1155           packlen++;
1156         }
1157       }
1158     }
1159 
1160     /* Check i-th diagonal entry */
1161     if (C->force_diagonals && !seen[i]) {
1162       PetscInt *PETSC_RESTRICT slot;
1163       PetscCall(PetscSegBufferGetInts(segrow, 1, &slot));
1164       *slot   = i;
1165       seen[i] = 1;
1166       packlen++;
1167     }
1168 
1169     PetscCall(PetscSegBufferGetInts(seg, packlen, &crow));
1170     PetscCall(PetscSegBufferExtractTo(segrow, crow));
1171     PetscCall(PetscSortInt(packlen, crow));
1172     ci[i + 1] = ci[i] + packlen;
1173     for (j = 0; j < packlen; j++) seen[crow[j]] = 0;
1174   }
1175   PetscCall(PetscSegBufferDestroy(&segrow));
1176   PetscCall(PetscFree(seen));
1177 
1178   /* Column indices are in the segmented buffer */
1179   PetscCall(PetscSegBufferExtractAlloc(seg, &cj));
1180   PetscCall(PetscSegBufferDestroy(&seg));
1181 
1182   /* put together the new symbolic matrix */
1183   PetscCall(MatSetSeqAIJWithArrays_private(PetscObjectComm((PetscObject)A), am, bn, ci, cj, NULL, ((PetscObject)A)->type_name, C));
1184   PetscCall(MatSetBlockSizesFromMats(C, A, B));
1185 
1186   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
1187   /* These are PETSc arrays, so change flags so arrays can be deleted by PETSc */
1188   c          = (Mat_SeqAIJ *)C->data;
1189   c->free_a  = PETSC_TRUE;
1190   c->free_ij = PETSC_TRUE;
1191   c->nonew   = 0;
1192 
1193   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqAIJ_Sorted;
1194 
1195   /* set MatInfo */
1196   afill = (PetscReal)ci[am] / PetscMax(ai[am] + bi[bm], 1) + 1.e-5;
1197   if (afill < 1.0) afill = 1.0;
1198   C->info.mallocs           = ndouble;
1199   C->info.fill_ratio_given  = fill;
1200   C->info.fill_ratio_needed = afill;
1201 
1202 #if defined(PETSC_USE_INFO)
1203   if (ci[am]) {
1204     PetscCall(PetscInfo(C, "Reallocs %" PetscInt_FMT "; Fill ratio: given %g needed %g.\n", ndouble, (double)fill, (double)afill));
1205     PetscCall(PetscInfo(C, "Use MatMatMult(A,B,MatReuse,%g,&C) for best performance.;\n", (double)afill));
1206   } else {
1207     PetscCall(PetscInfo(C, "Empty matrix product\n"));
1208   }
1209 #endif
1210   PetscFunctionReturn(PETSC_SUCCESS);
1211 }
1212 
1213 static PetscErrorCode MatDestroy_SeqAIJ_MatMatMultTrans(void *data)
1214 {
1215   Mat_MatMatTransMult *abt = (Mat_MatMatTransMult *)data;
1216 
1217   PetscFunctionBegin;
1218   PetscCall(MatTransposeColoringDestroy(&abt->matcoloring));
1219   PetscCall(MatDestroy(&abt->Bt_den));
1220   PetscCall(MatDestroy(&abt->ABt_den));
1221   PetscCall(PetscFree(abt));
1222   PetscFunctionReturn(PETSC_SUCCESS);
1223 }
1224 
1225 PetscErrorCode MatMatTransposeMultSymbolic_SeqAIJ_SeqAIJ(Mat A, Mat B, PetscReal fill, Mat C)
1226 {
1227   Mat                  Bt;
1228   Mat_MatMatTransMult *abt;
1229   Mat_Product         *product = C->product;
1230   char                *alg;
1231 
1232   PetscFunctionBegin;
1233   PetscCheck(product, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing product struct");
1234   PetscCheck(!product->data, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Extra product struct not empty");
1235 
1236   /* create symbolic Bt */
1237   PetscCall(MatTransposeSymbolic(B, &Bt));
1238   PetscCall(MatSetBlockSizes(Bt, PetscAbs(A->cmap->bs), PetscAbs(B->cmap->bs)));
1239   PetscCall(MatSetType(Bt, ((PetscObject)A)->type_name));
1240 
1241   /* get symbolic C=A*Bt */
1242   PetscCall(PetscStrallocpy(product->alg, &alg));
1243   PetscCall(MatProductSetAlgorithm(C, "sorted")); /* set algorithm for C = A*Bt */
1244   PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ(A, Bt, fill, C));
1245   PetscCall(MatProductSetAlgorithm(C, alg)); /* resume original algorithm for ABt product */
1246   PetscCall(PetscFree(alg));
1247 
1248   /* create a supporting struct for reuse intermediate dense matrices with matcoloring */
1249   PetscCall(PetscNew(&abt));
1250 
1251   product->data    = abt;
1252   product->destroy = MatDestroy_SeqAIJ_MatMatMultTrans;
1253 
1254   C->ops->mattransposemultnumeric = MatMatTransposeMultNumeric_SeqAIJ_SeqAIJ;
1255 
1256   abt->usecoloring = PETSC_FALSE;
1257   PetscCall(PetscStrcmp(product->alg, "color", &abt->usecoloring));
1258   if (abt->usecoloring) {
1259     /* Create MatTransposeColoring from symbolic C=A*B^T */
1260     MatTransposeColoring matcoloring;
1261     MatColoring          coloring;
1262     ISColoring           iscoloring;
1263     Mat                  Bt_dense, C_dense;
1264 
1265     /* inode causes memory problem */
1266     PetscCall(MatSetOption(C, MAT_USE_INODES, PETSC_FALSE));
1267 
1268     PetscCall(MatColoringCreate(C, &coloring));
1269     PetscCall(MatColoringSetDistance(coloring, 2));
1270     PetscCall(MatColoringSetType(coloring, MATCOLORINGSL));
1271     PetscCall(MatColoringSetFromOptions(coloring));
1272     PetscCall(MatColoringApply(coloring, &iscoloring));
1273     PetscCall(MatColoringDestroy(&coloring));
1274     PetscCall(MatTransposeColoringCreate(C, iscoloring, &matcoloring));
1275 
1276     abt->matcoloring = matcoloring;
1277 
1278     PetscCall(ISColoringDestroy(&iscoloring));
1279 
1280     /* Create Bt_dense and C_dense = A*Bt_dense */
1281     PetscCall(MatCreate(PETSC_COMM_SELF, &Bt_dense));
1282     PetscCall(MatSetSizes(Bt_dense, A->cmap->n, matcoloring->ncolors, A->cmap->n, matcoloring->ncolors));
1283     PetscCall(MatSetType(Bt_dense, MATSEQDENSE));
1284     PetscCall(MatSeqDenseSetPreallocation(Bt_dense, NULL));
1285 
1286     Bt_dense->assembled = PETSC_TRUE;
1287     abt->Bt_den         = Bt_dense;
1288 
1289     PetscCall(MatCreate(PETSC_COMM_SELF, &C_dense));
1290     PetscCall(MatSetSizes(C_dense, A->rmap->n, matcoloring->ncolors, A->rmap->n, matcoloring->ncolors));
1291     PetscCall(MatSetType(C_dense, MATSEQDENSE));
1292     PetscCall(MatSeqDenseSetPreallocation(C_dense, NULL));
1293 
1294     Bt_dense->assembled = PETSC_TRUE;
1295     abt->ABt_den        = C_dense;
1296 
1297 #if defined(PETSC_USE_INFO)
1298     {
1299       Mat_SeqAIJ *c = (Mat_SeqAIJ *)C->data;
1300       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,
1301                           Bt_dense->cmap->n, c->nz, A->rmap->n * matcoloring->ncolors, (double)(((PetscReal)c->nz) / ((PetscReal)(A->rmap->n * matcoloring->ncolors)))));
1302     }
1303 #endif
1304   }
1305   /* clean up */
1306   PetscCall(MatDestroy(&Bt));
1307   PetscFunctionReturn(PETSC_SUCCESS);
1308 }
1309 
1310 PetscErrorCode MatMatTransposeMultNumeric_SeqAIJ_SeqAIJ(Mat A, Mat B, Mat C)
1311 {
1312   Mat_SeqAIJ          *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c = (Mat_SeqAIJ *)C->data;
1313   PetscInt            *ai = a->i, *aj = a->j, *bi = b->i, *bj = b->j, anzi, bnzj, nexta, nextb, *acol, *bcol, brow;
1314   PetscInt             cm = C->rmap->n, *ci = c->i, *cj = c->j, i, j, cnzi, *ccol;
1315   PetscLogDouble       flops = 0.0;
1316   MatScalar           *aa = a->a, *aval, *ba = b->a, *bval, *ca, *cval;
1317   Mat_MatMatTransMult *abt;
1318   Mat_Product         *product = C->product;
1319 
1320   PetscFunctionBegin;
1321   PetscCheck(product, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing product struct");
1322   abt = (Mat_MatMatTransMult *)product->data;
1323   PetscCheck(abt, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing product struct");
1324   /* clear old values in C */
1325   if (!c->a) {
1326     PetscCall(PetscCalloc1(ci[cm] + 1, &ca));
1327     c->a      = ca;
1328     c->free_a = PETSC_TRUE;
1329   } else {
1330     ca = c->a;
1331     PetscCall(PetscArrayzero(ca, ci[cm] + 1));
1332   }
1333 
1334   if (abt->usecoloring) {
1335     MatTransposeColoring matcoloring = abt->matcoloring;
1336     Mat                  Bt_dense, C_dense = abt->ABt_den;
1337 
1338     /* Get Bt_dense by Apply MatTransposeColoring to B */
1339     Bt_dense = abt->Bt_den;
1340     PetscCall(MatTransColoringApplySpToDen(matcoloring, B, Bt_dense));
1341 
1342     /* C_dense = A*Bt_dense */
1343     PetscCall(MatMatMultNumeric_SeqAIJ_SeqDense(A, Bt_dense, C_dense));
1344 
1345     /* Recover C from C_dense */
1346     PetscCall(MatTransColoringApplyDenToSp(matcoloring, C_dense, C));
1347     PetscFunctionReturn(PETSC_SUCCESS);
1348   }
1349 
1350   for (i = 0; i < cm; i++) {
1351     anzi = ai[i + 1] - ai[i];
1352     acol = PetscSafePointerPlusOffset(aj, ai[i]);
1353     aval = PetscSafePointerPlusOffset(aa, ai[i]);
1354     cnzi = ci[i + 1] - ci[i];
1355     ccol = PetscSafePointerPlusOffset(cj, ci[i]);
1356     cval = ca + ci[i];
1357     for (j = 0; j < cnzi; j++) {
1358       brow = ccol[j];
1359       bnzj = bi[brow + 1] - bi[brow];
1360       bcol = bj + bi[brow];
1361       bval = ba + bi[brow];
1362 
1363       /* perform sparse inner-product c(i,j)=A[i,:]*B[j,:]^T */
1364       nexta = 0;
1365       nextb = 0;
1366       while (nexta < anzi && nextb < bnzj) {
1367         while (nexta < anzi && acol[nexta] < bcol[nextb]) nexta++;
1368         if (nexta == anzi) break;
1369         while (nextb < bnzj && acol[nexta] > bcol[nextb]) nextb++;
1370         if (nextb == bnzj) break;
1371         if (acol[nexta] == bcol[nextb]) {
1372           cval[j] += aval[nexta] * bval[nextb];
1373           nexta++;
1374           nextb++;
1375           flops += 2;
1376         }
1377       }
1378     }
1379   }
1380   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
1381   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
1382   PetscCall(PetscLogFlops(flops));
1383   PetscFunctionReturn(PETSC_SUCCESS);
1384 }
1385 
1386 PetscErrorCode MatDestroy_SeqAIJ_MatTransMatMult(void *data)
1387 {
1388   Mat_MatTransMatMult *atb = (Mat_MatTransMatMult *)data;
1389 
1390   PetscFunctionBegin;
1391   PetscCall(MatDestroy(&atb->At));
1392   if (atb->destroy) PetscCall((*atb->destroy)(atb->data));
1393   PetscCall(PetscFree(atb));
1394   PetscFunctionReturn(PETSC_SUCCESS);
1395 }
1396 
1397 PetscErrorCode MatTransposeMatMultSymbolic_SeqAIJ_SeqAIJ(Mat A, Mat B, PetscReal fill, Mat C)
1398 {
1399   Mat          At      = NULL;
1400   Mat_Product *product = C->product;
1401   PetscBool    flg, def, square;
1402 
1403   PetscFunctionBegin;
1404   MatCheckProduct(C, 4);
1405   square = (PetscBool)(A == B && A->symmetric == PETSC_BOOL3_TRUE);
1406   /* outerproduct */
1407   PetscCall(PetscStrcmp(product->alg, "outerproduct", &flg));
1408   if (flg) {
1409     /* create symbolic At */
1410     if (!square) {
1411       PetscCall(MatTransposeSymbolic(A, &At));
1412       PetscCall(MatSetBlockSizes(At, PetscAbs(A->cmap->bs), PetscAbs(B->cmap->bs)));
1413       PetscCall(MatSetType(At, ((PetscObject)A)->type_name));
1414     }
1415     /* get symbolic C=At*B */
1416     PetscCall(MatProductSetAlgorithm(C, "sorted"));
1417     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ(square ? A : At, B, fill, C));
1418 
1419     /* clean up */
1420     if (!square) PetscCall(MatDestroy(&At));
1421 
1422     C->ops->mattransposemultnumeric = MatTransposeMatMultNumeric_SeqAIJ_SeqAIJ; /* outerproduct */
1423     PetscCall(MatProductSetAlgorithm(C, "outerproduct"));
1424     PetscFunctionReturn(PETSC_SUCCESS);
1425   }
1426 
1427   /* matmatmult */
1428   PetscCall(PetscStrcmp(product->alg, "default", &def));
1429   PetscCall(PetscStrcmp(product->alg, "at*b", &flg));
1430   if (flg || def) {
1431     Mat_MatTransMatMult *atb;
1432 
1433     PetscCheck(!product->data, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Extra product struct not empty");
1434     PetscCall(PetscNew(&atb));
1435     if (!square) PetscCall(MatTranspose(A, MAT_INITIAL_MATRIX, &At));
1436     PetscCall(MatProductSetAlgorithm(C, "sorted"));
1437     PetscCall(MatMatMultSymbolic_SeqAIJ_SeqAIJ(square ? A : At, B, fill, C));
1438     PetscCall(MatProductSetAlgorithm(C, "at*b"));
1439     product->data    = atb;
1440     product->destroy = MatDestroy_SeqAIJ_MatTransMatMult;
1441     atb->At          = At;
1442 
1443     C->ops->mattransposemultnumeric = NULL; /* see MatProductNumeric_AtB_SeqAIJ_SeqAIJ */
1444     PetscFunctionReturn(PETSC_SUCCESS);
1445   }
1446 
1447   SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "Mat Product Algorithm is not supported");
1448 }
1449 
1450 PetscErrorCode MatTransposeMatMultNumeric_SeqAIJ_SeqAIJ(Mat A, Mat B, Mat C)
1451 {
1452   Mat_SeqAIJ    *a = (Mat_SeqAIJ *)A->data, *b = (Mat_SeqAIJ *)B->data, *c = (Mat_SeqAIJ *)C->data;
1453   PetscInt       am = A->rmap->n, anzi, *ai = a->i, *aj = a->j, *bi = b->i, *bj, bnzi, nextb;
1454   PetscInt       cm = C->rmap->n, *ci = c->i, *cj = c->j, crow, *cjj, i, j, k;
1455   PetscLogDouble flops = 0.0;
1456   MatScalar     *aa    = a->a, *ba, *ca, *caj;
1457 
1458   PetscFunctionBegin;
1459   if (!c->a) {
1460     PetscCall(PetscCalloc1(ci[cm] + 1, &ca));
1461 
1462     c->a      = ca;
1463     c->free_a = PETSC_TRUE;
1464   } else {
1465     ca = c->a;
1466     PetscCall(PetscArrayzero(ca, ci[cm]));
1467   }
1468 
1469   /* compute A^T*B using outer product (A^T)[:,i]*B[i,:] */
1470   for (i = 0; i < am; i++) {
1471     bj   = b->j + bi[i];
1472     ba   = b->a + bi[i];
1473     bnzi = bi[i + 1] - bi[i];
1474     anzi = ai[i + 1] - ai[i];
1475     for (j = 0; j < anzi; j++) {
1476       nextb = 0;
1477       crow  = *aj++;
1478       cjj   = cj + ci[crow];
1479       caj   = ca + ci[crow];
1480       /* perform sparse axpy operation.  Note cjj includes bj. */
1481       for (k = 0; nextb < bnzi; k++) {
1482         if (cjj[k] == *(bj + nextb)) { /* ccol == bcol */
1483           caj[k] += (*aa) * (*(ba + nextb));
1484           nextb++;
1485         }
1486       }
1487       flops += 2 * bnzi;
1488       aa++;
1489     }
1490   }
1491 
1492   /* Assemble the final matrix and clean up */
1493   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
1494   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
1495   PetscCall(PetscLogFlops(flops));
1496   PetscFunctionReturn(PETSC_SUCCESS);
1497 }
1498 
1499 PetscErrorCode MatMatMultSymbolic_SeqAIJ_SeqDense(Mat A, Mat B, PetscReal fill, Mat C)
1500 {
1501   PetscFunctionBegin;
1502   PetscCall(MatMatMultSymbolic_SeqDense_SeqDense(A, B, 0.0, C));
1503   C->ops->matmultnumeric = MatMatMultNumeric_SeqAIJ_SeqDense;
1504   PetscFunctionReturn(PETSC_SUCCESS);
1505 }
1506 
1507 PETSC_INTERN PetscErrorCode MatMatMultNumericAdd_SeqAIJ_SeqDense(Mat A, Mat B, Mat C, const PetscBool add)
1508 {
1509   Mat_SeqAIJ        *a = (Mat_SeqAIJ *)A->data;
1510   PetscScalar       *c, r1, r2, r3, r4, *c1, *c2, *c3, *c4;
1511   const PetscScalar *aa, *b, *b1, *b2, *b3, *b4, *av;
1512   const PetscInt    *aj;
1513   PetscInt           cm = C->rmap->n, cn = B->cmap->n, bm, am = A->rmap->n;
1514   PetscInt           clda;
1515   PetscInt           am4, bm4, col, i, j, n;
1516 
1517   PetscFunctionBegin;
1518   if (!cm || !cn) PetscFunctionReturn(PETSC_SUCCESS);
1519   PetscCall(MatSeqAIJGetArrayRead(A, &av));
1520   if (add) {
1521     PetscCall(MatDenseGetArray(C, &c));
1522   } else {
1523     PetscCall(MatDenseGetArrayWrite(C, &c));
1524   }
1525   PetscCall(MatDenseGetArrayRead(B, &b));
1526   PetscCall(MatDenseGetLDA(B, &bm));
1527   PetscCall(MatDenseGetLDA(C, &clda));
1528   am4 = 4 * clda;
1529   bm4 = 4 * bm;
1530   if (b) {
1531     b1 = b;
1532     b2 = b1 + bm;
1533     b3 = b2 + bm;
1534     b4 = b3 + bm;
1535   } else b1 = b2 = b3 = b4 = NULL;
1536   c1 = c;
1537   c2 = c1 + clda;
1538   c3 = c2 + clda;
1539   c4 = c3 + clda;
1540   for (col = 0; col < (cn / 4) * 4; col += 4) { /* over columns of C */
1541     for (i = 0; i < am; i++) {                  /* over rows of A in those columns */
1542       r1 = r2 = r3 = r4 = 0.0;
1543       n                 = a->i[i + 1] - a->i[i];
1544       aj                = PetscSafePointerPlusOffset(a->j, a->i[i]);
1545       aa                = PetscSafePointerPlusOffset(av, a->i[i]);
1546       for (j = 0; j < n; j++) {
1547         const PetscScalar aatmp = aa[j];
1548         const PetscInt    ajtmp = aj[j];
1549         r1 += aatmp * b1[ajtmp];
1550         r2 += aatmp * b2[ajtmp];
1551         r3 += aatmp * b3[ajtmp];
1552         r4 += aatmp * b4[ajtmp];
1553       }
1554       if (add) {
1555         c1[i] += r1;
1556         c2[i] += r2;
1557         c3[i] += r3;
1558         c4[i] += r4;
1559       } else {
1560         c1[i] = r1;
1561         c2[i] = r2;
1562         c3[i] = r3;
1563         c4[i] = r4;
1564       }
1565     }
1566     if (b) {
1567       b1 += bm4;
1568       b2 += bm4;
1569       b3 += bm4;
1570       b4 += bm4;
1571     }
1572     c1 += am4;
1573     c2 += am4;
1574     c3 += am4;
1575     c4 += am4;
1576   }
1577   /* process remaining columns */
1578   if (col != cn) {
1579     PetscInt rc = cn - col;
1580 
1581     if (rc == 1) {
1582       for (i = 0; i < am; i++) {
1583         r1 = 0.0;
1584         n  = a->i[i + 1] - a->i[i];
1585         aj = PetscSafePointerPlusOffset(a->j, a->i[i]);
1586         aa = PetscSafePointerPlusOffset(av, a->i[i]);
1587         for (j = 0; j < n; j++) r1 += aa[j] * b1[aj[j]];
1588         if (add) c1[i] += r1;
1589         else c1[i] = r1;
1590       }
1591     } else if (rc == 2) {
1592       for (i = 0; i < am; i++) {
1593         r1 = r2 = 0.0;
1594         n       = a->i[i + 1] - a->i[i];
1595         aj      = PetscSafePointerPlusOffset(a->j, a->i[i]);
1596         aa      = PetscSafePointerPlusOffset(av, a->i[i]);
1597         for (j = 0; j < n; j++) {
1598           const PetscScalar aatmp = aa[j];
1599           const PetscInt    ajtmp = aj[j];
1600           r1 += aatmp * b1[ajtmp];
1601           r2 += aatmp * b2[ajtmp];
1602         }
1603         if (add) {
1604           c1[i] += r1;
1605           c2[i] += r2;
1606         } else {
1607           c1[i] = r1;
1608           c2[i] = r2;
1609         }
1610       }
1611     } else {
1612       for (i = 0; i < am; i++) {
1613         r1 = r2 = r3 = 0.0;
1614         n            = a->i[i + 1] - a->i[i];
1615         aj           = PetscSafePointerPlusOffset(a->j, a->i[i]);
1616         aa           = PetscSafePointerPlusOffset(av, a->i[i]);
1617         for (j = 0; j < n; j++) {
1618           const PetscScalar aatmp = aa[j];
1619           const PetscInt    ajtmp = aj[j];
1620           r1 += aatmp * b1[ajtmp];
1621           r2 += aatmp * b2[ajtmp];
1622           r3 += aatmp * b3[ajtmp];
1623         }
1624         if (add) {
1625           c1[i] += r1;
1626           c2[i] += r2;
1627           c3[i] += r3;
1628         } else {
1629           c1[i] = r1;
1630           c2[i] = r2;
1631           c3[i] = r3;
1632         }
1633       }
1634     }
1635   }
1636   PetscCall(PetscLogFlops(cn * (2.0 * a->nz)));
1637   if (add) {
1638     PetscCall(MatDenseRestoreArray(C, &c));
1639   } else {
1640     PetscCall(MatDenseRestoreArrayWrite(C, &c));
1641   }
1642   PetscCall(MatDenseRestoreArrayRead(B, &b));
1643   PetscCall(MatSeqAIJRestoreArrayRead(A, &av));
1644   PetscFunctionReturn(PETSC_SUCCESS);
1645 }
1646 
1647 PetscErrorCode MatMatMultNumeric_SeqAIJ_SeqDense(Mat A, Mat B, Mat C)
1648 {
1649   PetscFunctionBegin;
1650   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);
1651   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);
1652   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);
1653 
1654   PetscCall(MatMatMultNumericAdd_SeqAIJ_SeqDense(A, B, C, PETSC_FALSE));
1655   PetscFunctionReturn(PETSC_SUCCESS);
1656 }
1657 
1658 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_SeqDense_AB(Mat C)
1659 {
1660   PetscFunctionBegin;
1661   C->ops->matmultsymbolic = MatMatMultSymbolic_SeqAIJ_SeqDense;
1662   C->ops->productsymbolic = MatProductSymbolic_AB;
1663   PetscFunctionReturn(PETSC_SUCCESS);
1664 }
1665 
1666 PETSC_INTERN PetscErrorCode MatTMatTMultSymbolic_SeqAIJ_SeqDense(Mat, Mat, PetscReal, Mat);
1667 
1668 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_SeqDense_AtB(Mat C)
1669 {
1670   PetscFunctionBegin;
1671   C->ops->transposematmultsymbolic = MatTMatTMultSymbolic_SeqAIJ_SeqDense;
1672   C->ops->productsymbolic          = MatProductSymbolic_AtB;
1673   PetscFunctionReturn(PETSC_SUCCESS);
1674 }
1675 
1676 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_SeqDense_ABt(Mat C)
1677 {
1678   PetscFunctionBegin;
1679   C->ops->mattransposemultsymbolic = MatTMatTMultSymbolic_SeqAIJ_SeqDense;
1680   C->ops->productsymbolic          = MatProductSymbolic_ABt;
1681   PetscFunctionReturn(PETSC_SUCCESS);
1682 }
1683 
1684 PETSC_INTERN PetscErrorCode MatProductSetFromOptions_SeqAIJ_SeqDense(Mat C)
1685 {
1686   Mat_Product *product = C->product;
1687 
1688   PetscFunctionBegin;
1689   switch (product->type) {
1690   case MATPRODUCT_AB:
1691     PetscCall(MatProductSetFromOptions_SeqAIJ_SeqDense_AB(C));
1692     break;
1693   case MATPRODUCT_AtB:
1694     PetscCall(MatProductSetFromOptions_SeqAIJ_SeqDense_AtB(C));
1695     break;
1696   case MATPRODUCT_ABt:
1697     PetscCall(MatProductSetFromOptions_SeqAIJ_SeqDense_ABt(C));
1698     break;
1699   default:
1700     break;
1701   }
1702   PetscFunctionReturn(PETSC_SUCCESS);
1703 }
1704 
1705 static PetscErrorCode MatProductSetFromOptions_SeqXBAIJ_SeqDense_AB(Mat C)
1706 {
1707   Mat_Product *product = C->product;
1708   Mat          A       = product->A;
1709   PetscBool    baij;
1710 
1711   PetscFunctionBegin;
1712   PetscCall(PetscObjectTypeCompare((PetscObject)A, MATSEQBAIJ, &baij));
1713   if (!baij) { /* A is seqsbaij */
1714     PetscBool sbaij;
1715     PetscCall(PetscObjectTypeCompare((PetscObject)A, MATSEQSBAIJ, &sbaij));
1716     PetscCheck(sbaij, PetscObjectComm((PetscObject)C), PETSC_ERR_ARG_WRONGSTATE, "Mat must be either seqbaij or seqsbaij format");
1717 
1718     C->ops->matmultsymbolic = MatMatMultSymbolic_SeqSBAIJ_SeqDense;
1719   } else { /* A is seqbaij */
1720     C->ops->matmultsymbolic = MatMatMultSymbolic_SeqBAIJ_SeqDense;
1721   }
1722 
1723   C->ops->productsymbolic = MatProductSymbolic_AB;
1724   PetscFunctionReturn(PETSC_SUCCESS);
1725 }
1726 
1727 PETSC_INTERN PetscErrorCode MatProductSetFromOptions_SeqXBAIJ_SeqDense(Mat C)
1728 {
1729   Mat_Product *product = C->product;
1730 
1731   PetscFunctionBegin;
1732   MatCheckProduct(C, 1);
1733   PetscCheck(product->A, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing A");
1734   if (product->type == MATPRODUCT_AB || (product->type == MATPRODUCT_AtB && product->A->symmetric == PETSC_BOOL3_TRUE)) PetscCall(MatProductSetFromOptions_SeqXBAIJ_SeqDense_AB(C));
1735   PetscFunctionReturn(PETSC_SUCCESS);
1736 }
1737 
1738 static PetscErrorCode MatProductSetFromOptions_SeqDense_SeqAIJ_AB(Mat C)
1739 {
1740   PetscFunctionBegin;
1741   C->ops->matmultsymbolic = MatMatMultSymbolic_SeqDense_SeqAIJ;
1742   C->ops->productsymbolic = MatProductSymbolic_AB;
1743   PetscFunctionReturn(PETSC_SUCCESS);
1744 }
1745 
1746 PETSC_INTERN PetscErrorCode MatProductSetFromOptions_SeqDense_SeqAIJ(Mat C)
1747 {
1748   Mat_Product *product = C->product;
1749 
1750   PetscFunctionBegin;
1751   if (product->type == MATPRODUCT_AB) PetscCall(MatProductSetFromOptions_SeqDense_SeqAIJ_AB(C));
1752   PetscFunctionReturn(PETSC_SUCCESS);
1753 }
1754 
1755 PetscErrorCode MatTransColoringApplySpToDen_SeqAIJ(MatTransposeColoring coloring, Mat B, Mat Btdense)
1756 {
1757   Mat_SeqAIJ   *b       = (Mat_SeqAIJ *)B->data;
1758   Mat_SeqDense *btdense = (Mat_SeqDense *)Btdense->data;
1759   PetscInt     *bi = b->i, *bj = b->j;
1760   PetscInt      m = Btdense->rmap->n, n = Btdense->cmap->n, j, k, l, col, anz, *btcol, brow, ncolumns;
1761   MatScalar    *btval, *btval_den, *ba = b->a;
1762   PetscInt     *columns = coloring->columns, *colorforcol = coloring->colorforcol, ncolors = coloring->ncolors;
1763 
1764   PetscFunctionBegin;
1765   btval_den = btdense->v;
1766   PetscCall(PetscArrayzero(btval_den, m * n));
1767   for (k = 0; k < ncolors; k++) {
1768     ncolumns = coloring->ncolumns[k];
1769     for (l = 0; l < ncolumns; l++) { /* insert a row of B to a column of Btdense */
1770       col   = *(columns + colorforcol[k] + l);
1771       btcol = bj + bi[col];
1772       btval = ba + bi[col];
1773       anz   = bi[col + 1] - bi[col];
1774       for (j = 0; j < anz; j++) {
1775         brow            = btcol[j];
1776         btval_den[brow] = btval[j];
1777       }
1778     }
1779     btval_den += m;
1780   }
1781   PetscFunctionReturn(PETSC_SUCCESS);
1782 }
1783 
1784 PetscErrorCode MatTransColoringApplyDenToSp_SeqAIJ(MatTransposeColoring matcoloring, Mat Cden, Mat Csp)
1785 {
1786   Mat_SeqAIJ        *csp = (Mat_SeqAIJ *)Csp->data;
1787   const PetscScalar *ca_den, *ca_den_ptr;
1788   PetscScalar       *ca = csp->a;
1789   PetscInt           k, l, m = Cden->rmap->n, ncolors = matcoloring->ncolors;
1790   PetscInt           brows = matcoloring->brows, *den2sp = matcoloring->den2sp;
1791   PetscInt           nrows, *row, *idx;
1792   PetscInt          *rows = matcoloring->rows, *colorforrow = matcoloring->colorforrow;
1793 
1794   PetscFunctionBegin;
1795   PetscCall(MatDenseGetArrayRead(Cden, &ca_den));
1796 
1797   if (brows > 0) {
1798     PetscInt *lstart, row_end, row_start;
1799     lstart = matcoloring->lstart;
1800     PetscCall(PetscArrayzero(lstart, ncolors));
1801 
1802     row_end = brows;
1803     if (row_end > m) row_end = m;
1804     for (row_start = 0; row_start < m; row_start += brows) { /* loop over row blocks of Csp */
1805       ca_den_ptr = ca_den;
1806       for (k = 0; k < ncolors; k++) { /* loop over colors (columns of Cden) */
1807         nrows = matcoloring->nrows[k];
1808         row   = rows + colorforrow[k];
1809         idx   = den2sp + colorforrow[k];
1810         for (l = lstart[k]; l < nrows; l++) {
1811           if (row[l] >= row_end) {
1812             lstart[k] = l;
1813             break;
1814           } else {
1815             ca[idx[l]] = ca_den_ptr[row[l]];
1816           }
1817         }
1818         ca_den_ptr += m;
1819       }
1820       row_end += brows;
1821       if (row_end > m) row_end = m;
1822     }
1823   } else { /* non-blocked impl: loop over columns of Csp - slow if Csp is large */
1824     ca_den_ptr = ca_den;
1825     for (k = 0; k < ncolors; k++) {
1826       nrows = matcoloring->nrows[k];
1827       row   = rows + colorforrow[k];
1828       idx   = den2sp + colorforrow[k];
1829       for (l = 0; l < nrows; l++) ca[idx[l]] = ca_den_ptr[row[l]];
1830       ca_den_ptr += m;
1831     }
1832   }
1833 
1834   PetscCall(MatDenseRestoreArrayRead(Cden, &ca_den));
1835 #if defined(PETSC_USE_INFO)
1836   if (matcoloring->brows > 0) {
1837     PetscCall(PetscInfo(Csp, "Loop over %" PetscInt_FMT " row blocks for den2sp\n", brows));
1838   } else {
1839     PetscCall(PetscInfo(Csp, "Loop over colors/columns of Cden, inefficient for large sparse matrix product \n"));
1840   }
1841 #endif
1842   PetscFunctionReturn(PETSC_SUCCESS);
1843 }
1844 
1845 PetscErrorCode MatTransposeColoringCreate_SeqAIJ(Mat mat, ISColoring iscoloring, MatTransposeColoring c)
1846 {
1847   PetscInt        i, n, nrows, Nbs, j, k, m, ncols, col, cm;
1848   const PetscInt *is, *ci, *cj, *row_idx;
1849   PetscInt        nis = iscoloring->n, *rowhit, bs = 1;
1850   IS             *isa;
1851   Mat_SeqAIJ     *csp = (Mat_SeqAIJ *)mat->data;
1852   PetscInt       *colorforrow, *rows, *rows_i, *idxhit, *spidx, *den2sp, *den2sp_i;
1853   PetscInt       *colorforcol, *columns, *columns_i, brows;
1854   PetscBool       flg;
1855 
1856   PetscFunctionBegin;
1857   PetscCall(ISColoringGetIS(iscoloring, PETSC_USE_POINTER, PETSC_IGNORE, &isa));
1858 
1859   /* bs >1 is not being tested yet! */
1860   Nbs       = mat->cmap->N / bs;
1861   c->M      = mat->rmap->N / bs; /* set total rows, columns and local rows */
1862   c->N      = Nbs;
1863   c->m      = c->M;
1864   c->rstart = 0;
1865   c->brows  = 100;
1866 
1867   c->ncolors = nis;
1868   PetscCall(PetscMalloc3(nis, &c->ncolumns, nis, &c->nrows, nis + 1, &colorforrow));
1869   PetscCall(PetscMalloc1(csp->nz + 1, &rows));
1870   PetscCall(PetscMalloc1(csp->nz + 1, &den2sp));
1871 
1872   brows = c->brows;
1873   PetscCall(PetscOptionsGetInt(NULL, NULL, "-matden2sp_brows", &brows, &flg));
1874   if (flg) c->brows = brows;
1875   if (brows > 0) PetscCall(PetscMalloc1(nis + 1, &c->lstart));
1876 
1877   colorforrow[0] = 0;
1878   rows_i         = rows;
1879   den2sp_i       = den2sp;
1880 
1881   PetscCall(PetscMalloc1(nis + 1, &colorforcol));
1882   PetscCall(PetscMalloc1(Nbs + 1, &columns));
1883 
1884   colorforcol[0] = 0;
1885   columns_i      = columns;
1886 
1887   /* get column-wise storage of mat */
1888   PetscCall(MatGetColumnIJ_SeqAIJ_Color(mat, 0, PETSC_FALSE, PETSC_FALSE, &ncols, &ci, &cj, &spidx, NULL));
1889 
1890   cm = c->m;
1891   PetscCall(PetscMalloc1(cm + 1, &rowhit));
1892   PetscCall(PetscMalloc1(cm + 1, &idxhit));
1893   for (i = 0; i < nis; i++) { /* loop over color */
1894     PetscCall(ISGetLocalSize(isa[i], &n));
1895     PetscCall(ISGetIndices(isa[i], &is));
1896 
1897     c->ncolumns[i] = n;
1898     if (n) PetscCall(PetscArraycpy(columns_i, is, n));
1899     colorforcol[i + 1] = colorforcol[i] + n;
1900     columns_i += n;
1901 
1902     /* fast, crude version requires O(N*N) work */
1903     PetscCall(PetscArrayzero(rowhit, cm));
1904 
1905     for (j = 0; j < n; j++) { /* loop over columns*/
1906       col     = is[j];
1907       row_idx = cj + ci[col];
1908       m       = ci[col + 1] - ci[col];
1909       for (k = 0; k < m; k++) { /* loop over columns marking them in rowhit */
1910         idxhit[*row_idx]   = spidx[ci[col] + k];
1911         rowhit[*row_idx++] = col + 1;
1912       }
1913     }
1914     /* count the number of hits */
1915     nrows = 0;
1916     for (j = 0; j < cm; j++) {
1917       if (rowhit[j]) nrows++;
1918     }
1919     c->nrows[i]        = nrows;
1920     colorforrow[i + 1] = colorforrow[i] + nrows;
1921 
1922     nrows = 0;
1923     for (j = 0; j < cm; j++) { /* loop over rows */
1924       if (rowhit[j]) {
1925         rows_i[nrows]   = j;
1926         den2sp_i[nrows] = idxhit[j];
1927         nrows++;
1928       }
1929     }
1930     den2sp_i += nrows;
1931 
1932     PetscCall(ISRestoreIndices(isa[i], &is));
1933     rows_i += nrows;
1934   }
1935   PetscCall(MatRestoreColumnIJ_SeqAIJ_Color(mat, 0, PETSC_FALSE, PETSC_FALSE, &ncols, &ci, &cj, &spidx, NULL));
1936   PetscCall(PetscFree(rowhit));
1937   PetscCall(ISColoringRestoreIS(iscoloring, PETSC_USE_POINTER, &isa));
1938   PetscCheck(csp->nz == colorforrow[nis], PETSC_COMM_SELF, PETSC_ERR_PLIB, "csp->nz %" PetscInt_FMT " != colorforrow[nis] %" PetscInt_FMT, csp->nz, colorforrow[nis]);
1939 
1940   c->colorforrow = colorforrow;
1941   c->rows        = rows;
1942   c->den2sp      = den2sp;
1943   c->colorforcol = colorforcol;
1944   c->columns     = columns;
1945 
1946   PetscCall(PetscFree(idxhit));
1947   PetscFunctionReturn(PETSC_SUCCESS);
1948 }
1949 
1950 static PetscErrorCode MatProductNumeric_AtB_SeqAIJ_SeqAIJ(Mat C)
1951 {
1952   Mat_Product *product = C->product;
1953   Mat          A = product->A, B = product->B;
1954 
1955   PetscFunctionBegin;
1956   if (C->ops->mattransposemultnumeric) {
1957     /* Alg: "outerproduct" */
1958     PetscCall((*C->ops->mattransposemultnumeric)(A, B, C));
1959   } else {
1960     /* Alg: "matmatmult" -- C = At*B */
1961     Mat_MatTransMatMult *atb = (Mat_MatTransMatMult *)product->data;
1962 
1963     PetscCheck(atb, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing product struct");
1964     if (atb->At) {
1965       /* At is computed in MatTransposeMatMultSymbolic_SeqAIJ_SeqAIJ();
1966          user may have called MatProductReplaceMats() to get this A=product->A */
1967       PetscCall(MatTransposeSetPrecursor(A, atb->At));
1968       PetscCall(MatTranspose(A, MAT_REUSE_MATRIX, &atb->At));
1969     }
1970     PetscCall(MatMatMultNumeric_SeqAIJ_SeqAIJ(atb->At ? atb->At : A, B, C));
1971   }
1972   PetscFunctionReturn(PETSC_SUCCESS);
1973 }
1974 
1975 static PetscErrorCode MatProductSymbolic_AtB_SeqAIJ_SeqAIJ(Mat C)
1976 {
1977   Mat_Product *product = C->product;
1978   Mat          A = product->A, B = product->B;
1979   PetscReal    fill = product->fill;
1980 
1981   PetscFunctionBegin;
1982   PetscCall(MatTransposeMatMultSymbolic_SeqAIJ_SeqAIJ(A, B, fill, C));
1983 
1984   C->ops->productnumeric = MatProductNumeric_AtB_SeqAIJ_SeqAIJ;
1985   PetscFunctionReturn(PETSC_SUCCESS);
1986 }
1987 
1988 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_AB(Mat C)
1989 {
1990   Mat_Product *product = C->product;
1991   PetscInt     alg     = 0; /* default algorithm */
1992   PetscBool    flg     = PETSC_FALSE;
1993 #if !defined(PETSC_HAVE_HYPRE)
1994   const char *algTypes[7] = {"sorted", "scalable", "scalable_fast", "heap", "btheap", "llcondensed", "rowmerge"};
1995   PetscInt    nalg        = 7;
1996 #else
1997   const char *algTypes[8] = {"sorted", "scalable", "scalable_fast", "heap", "btheap", "llcondensed", "rowmerge", "hypre"};
1998   PetscInt    nalg        = 8;
1999 #endif
2000 
2001   PetscFunctionBegin;
2002   /* Set default algorithm */
2003   PetscCall(PetscStrcmp(C->product->alg, "default", &flg));
2004   if (flg) PetscCall(MatProductSetAlgorithm(C, (MatProductAlgorithm)algTypes[alg]));
2005 
2006   /* Get runtime option */
2007   if (product->api_user) {
2008     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatMatMult", "Mat");
2009     PetscCall(PetscOptionsEList("-matmatmult_via", "Algorithmic approach", "MatMatMult", algTypes, nalg, algTypes[0], &alg, &flg));
2010     PetscOptionsEnd();
2011   } else {
2012     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_AB", "Mat");
2013     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_AB", algTypes, nalg, algTypes[0], &alg, &flg));
2014     PetscOptionsEnd();
2015   }
2016   if (flg) PetscCall(MatProductSetAlgorithm(C, (MatProductAlgorithm)algTypes[alg]));
2017 
2018   C->ops->productsymbolic = MatProductSymbolic_AB;
2019   C->ops->matmultsymbolic = MatMatMultSymbolic_SeqAIJ_SeqAIJ;
2020   PetscFunctionReturn(PETSC_SUCCESS);
2021 }
2022 
2023 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_AtB(Mat C)
2024 {
2025   Mat_Product *product     = C->product;
2026   PetscInt     alg         = 0; /* default algorithm */
2027   PetscBool    flg         = PETSC_FALSE;
2028   const char  *algTypes[3] = {"default", "at*b", "outerproduct"};
2029   PetscInt     nalg        = 3;
2030 
2031   PetscFunctionBegin;
2032   /* Get runtime option */
2033   if (product->api_user) {
2034     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatTransposeMatMult", "Mat");
2035     PetscCall(PetscOptionsEList("-mattransposematmult_via", "Algorithmic approach", "MatTransposeMatMult", algTypes, nalg, algTypes[alg], &alg, &flg));
2036     PetscOptionsEnd();
2037   } else {
2038     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_AtB", "Mat");
2039     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_AtB", algTypes, nalg, algTypes[alg], &alg, &flg));
2040     PetscOptionsEnd();
2041   }
2042   if (flg) PetscCall(MatProductSetAlgorithm(C, (MatProductAlgorithm)algTypes[alg]));
2043 
2044   C->ops->productsymbolic = MatProductSymbolic_AtB_SeqAIJ_SeqAIJ;
2045   PetscFunctionReturn(PETSC_SUCCESS);
2046 }
2047 
2048 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_ABt(Mat C)
2049 {
2050   Mat_Product *product     = C->product;
2051   PetscInt     alg         = 0; /* default algorithm */
2052   PetscBool    flg         = PETSC_FALSE;
2053   const char  *algTypes[2] = {"default", "color"};
2054   PetscInt     nalg        = 2;
2055 
2056   PetscFunctionBegin;
2057   /* Set default algorithm */
2058   PetscCall(PetscStrcmp(C->product->alg, "default", &flg));
2059   if (!flg) {
2060     alg = 1;
2061     PetscCall(MatProductSetAlgorithm(C, (MatProductAlgorithm)algTypes[alg]));
2062   }
2063 
2064   /* Get runtime option */
2065   if (product->api_user) {
2066     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatMatTransposeMult", "Mat");
2067     PetscCall(PetscOptionsEList("-matmattransmult_via", "Algorithmic approach", "MatMatTransposeMult", algTypes, nalg, algTypes[alg], &alg, &flg));
2068     PetscOptionsEnd();
2069   } else {
2070     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_ABt", "Mat");
2071     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_ABt", algTypes, nalg, algTypes[alg], &alg, &flg));
2072     PetscOptionsEnd();
2073   }
2074   if (flg) PetscCall(MatProductSetAlgorithm(C, (MatProductAlgorithm)algTypes[alg]));
2075 
2076   C->ops->mattransposemultsymbolic = MatMatTransposeMultSymbolic_SeqAIJ_SeqAIJ;
2077   C->ops->productsymbolic          = MatProductSymbolic_ABt;
2078   PetscFunctionReturn(PETSC_SUCCESS);
2079 }
2080 
2081 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_PtAP(Mat C)
2082 {
2083   Mat_Product *product = C->product;
2084   PetscBool    flg     = PETSC_FALSE;
2085   PetscInt     alg     = 0; /* default algorithm -- alg=1 should be default!!! */
2086 #if !defined(PETSC_HAVE_HYPRE)
2087   const char *algTypes[2] = {"scalable", "rap"};
2088   PetscInt    nalg        = 2;
2089 #else
2090   const char *algTypes[3] = {"scalable", "rap", "hypre"};
2091   PetscInt    nalg        = 3;
2092 #endif
2093 
2094   PetscFunctionBegin;
2095   /* Set default algorithm */
2096   PetscCall(PetscStrcmp(product->alg, "default", &flg));
2097   if (flg) PetscCall(MatProductSetAlgorithm(C, (MatProductAlgorithm)algTypes[alg]));
2098 
2099   /* Get runtime option */
2100   if (product->api_user) {
2101     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatPtAP", "Mat");
2102     PetscCall(PetscOptionsEList("-matptap_via", "Algorithmic approach", "MatPtAP", algTypes, nalg, algTypes[0], &alg, &flg));
2103     PetscOptionsEnd();
2104   } else {
2105     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_PtAP", "Mat");
2106     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_PtAP", algTypes, nalg, algTypes[0], &alg, &flg));
2107     PetscOptionsEnd();
2108   }
2109   if (flg) PetscCall(MatProductSetAlgorithm(C, (MatProductAlgorithm)algTypes[alg]));
2110 
2111   C->ops->productsymbolic = MatProductSymbolic_PtAP_SeqAIJ_SeqAIJ;
2112   PetscFunctionReturn(PETSC_SUCCESS);
2113 }
2114 
2115 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_RARt(Mat C)
2116 {
2117   Mat_Product *product     = C->product;
2118   PetscBool    flg         = PETSC_FALSE;
2119   PetscInt     alg         = 0; /* default algorithm */
2120   const char  *algTypes[3] = {"r*a*rt", "r*art", "coloring_rart"};
2121   PetscInt     nalg        = 3;
2122 
2123   PetscFunctionBegin;
2124   /* Set default algorithm */
2125   PetscCall(PetscStrcmp(product->alg, "default", &flg));
2126   if (flg) PetscCall(MatProductSetAlgorithm(C, (MatProductAlgorithm)algTypes[alg]));
2127 
2128   /* Get runtime option */
2129   if (product->api_user) {
2130     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatRARt", "Mat");
2131     PetscCall(PetscOptionsEList("-matrart_via", "Algorithmic approach", "MatRARt", algTypes, nalg, algTypes[0], &alg, &flg));
2132     PetscOptionsEnd();
2133   } else {
2134     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_RARt", "Mat");
2135     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_RARt", algTypes, nalg, algTypes[0], &alg, &flg));
2136     PetscOptionsEnd();
2137   }
2138   if (flg) PetscCall(MatProductSetAlgorithm(C, (MatProductAlgorithm)algTypes[alg]));
2139 
2140   C->ops->productsymbolic = MatProductSymbolic_RARt_SeqAIJ_SeqAIJ;
2141   PetscFunctionReturn(PETSC_SUCCESS);
2142 }
2143 
2144 /* ABC = A*B*C = A*(B*C); ABC's algorithm must be chosen from AB's algorithm */
2145 static PetscErrorCode MatProductSetFromOptions_SeqAIJ_ABC(Mat C)
2146 {
2147   Mat_Product *product     = C->product;
2148   PetscInt     alg         = 0; /* default algorithm */
2149   PetscBool    flg         = PETSC_FALSE;
2150   const char  *algTypes[7] = {"sorted", "scalable", "scalable_fast", "heap", "btheap", "llcondensed", "rowmerge"};
2151   PetscInt     nalg        = 7;
2152 
2153   PetscFunctionBegin;
2154   /* Set default algorithm */
2155   PetscCall(PetscStrcmp(product->alg, "default", &flg));
2156   if (flg) PetscCall(MatProductSetAlgorithm(C, (MatProductAlgorithm)algTypes[alg]));
2157 
2158   /* Get runtime option */
2159   if (product->api_user) {
2160     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatMatMatMult", "Mat");
2161     PetscCall(PetscOptionsEList("-matmatmatmult_via", "Algorithmic approach", "MatMatMatMult", algTypes, nalg, algTypes[alg], &alg, &flg));
2162     PetscOptionsEnd();
2163   } else {
2164     PetscOptionsBegin(PetscObjectComm((PetscObject)C), ((PetscObject)C)->prefix, "MatProduct_ABC", "Mat");
2165     PetscCall(PetscOptionsEList("-mat_product_algorithm", "Algorithmic approach", "MatProduct_ABC", algTypes, nalg, algTypes[alg], &alg, &flg));
2166     PetscOptionsEnd();
2167   }
2168   if (flg) PetscCall(MatProductSetAlgorithm(C, (MatProductAlgorithm)algTypes[alg]));
2169 
2170   C->ops->matmatmultsymbolic = MatMatMatMultSymbolic_SeqAIJ_SeqAIJ_SeqAIJ;
2171   C->ops->productsymbolic    = MatProductSymbolic_ABC;
2172   PetscFunctionReturn(PETSC_SUCCESS);
2173 }
2174 
2175 PetscErrorCode MatProductSetFromOptions_SeqAIJ(Mat C)
2176 {
2177   Mat_Product *product = C->product;
2178 
2179   PetscFunctionBegin;
2180   switch (product->type) {
2181   case MATPRODUCT_AB:
2182     PetscCall(MatProductSetFromOptions_SeqAIJ_AB(C));
2183     break;
2184   case MATPRODUCT_AtB:
2185     PetscCall(MatProductSetFromOptions_SeqAIJ_AtB(C));
2186     break;
2187   case MATPRODUCT_ABt:
2188     PetscCall(MatProductSetFromOptions_SeqAIJ_ABt(C));
2189     break;
2190   case MATPRODUCT_PtAP:
2191     PetscCall(MatProductSetFromOptions_SeqAIJ_PtAP(C));
2192     break;
2193   case MATPRODUCT_RARt:
2194     PetscCall(MatProductSetFromOptions_SeqAIJ_RARt(C));
2195     break;
2196   case MATPRODUCT_ABC:
2197     PetscCall(MatProductSetFromOptions_SeqAIJ_ABC(C));
2198     break;
2199   default:
2200     break;
2201   }
2202   PetscFunctionReturn(PETSC_SUCCESS);
2203 }
2204