xref: /petsc/src/mat/impls/aij/seq/matptap.c (revision 7601faf09de2bc280184d9c73acff348d5eb2a25)
1 
2 /*
3   Defines projective product routines where A is a SeqAIJ matrix
4           C = P^T * A * P
5 */
6 
7 #include <../src/mat/impls/aij/seq/aij.h>   /*I "petscmat.h" I*/
8 #include <../src/mat/utils/freespace.h>
9 #include <petscbt.h>
10 #include <petsctime.h>
11 
12 #undef __FUNCT__
13 #define __FUNCT__ "MatPtAP_SeqAIJ_SeqAIJ"
14 PetscErrorCode MatPtAP_SeqAIJ_SeqAIJ(Mat A,Mat P,MatReuse scall,PetscReal fill,Mat *C)
15 {
16   PetscErrorCode ierr;
17 
18   PetscFunctionBegin;
19   if (scall == MAT_INITIAL_MATRIX) {
20     ierr = MatPtAPSymbolic_SeqAIJ_SeqAIJ(A,P,fill,C);CHKERRQ(ierr);
21   }
22   ierr = (*(*C)->ops->ptapnumeric)(A,P,*C);CHKERRQ(ierr);
23   PetscFunctionReturn(0);
24 }
25 
26 #undef __FUNCT__
27 #define __FUNCT__ "MatDestroy_SeqAIJ_PtAP"
28 PetscErrorCode MatDestroy_SeqAIJ_PtAP(Mat A)
29 {
30   PetscErrorCode ierr;
31   Mat_SeqAIJ     *a    = (Mat_SeqAIJ*)A->data;
32   Mat_PtAP       *ptap = a->ptap;
33 
34   PetscFunctionBegin;
35   ierr = PetscFree(ptap->apa);CHKERRQ(ierr);
36   ierr = PetscFree(ptap->api);CHKERRQ(ierr);
37   ierr = PetscFree(ptap->apj);CHKERRQ(ierr);
38   ierr = (ptap->destroy)(A);CHKERRQ(ierr);
39   ierr = PetscFree(ptap);CHKERRQ(ierr);
40   PetscFunctionReturn(0);
41 }
42 
43 #undef __FUNCT__
44 #define __FUNCT__ "MatPtAPSymbolic_SeqAIJ_SeqAIJ_SparseAxpy"
45 PetscErrorCode MatPtAPSymbolic_SeqAIJ_SeqAIJ_SparseAxpy(Mat A,Mat P,PetscReal fill,Mat *C)
46 {
47   PetscErrorCode     ierr;
48   PetscFreeSpaceList free_space=NULL,current_space=NULL;
49   Mat_SeqAIJ         *a        = (Mat_SeqAIJ*)A->data,*p = (Mat_SeqAIJ*)P->data,*c;
50   PetscInt           *pti,*ptj,*ptJ,*ai=a->i,*aj=a->j,*ajj,*pi=p->i,*pj=p->j,*pjj;
51   PetscInt           *ci,*cj,*ptadenserow,*ptasparserow,*ptaj,nspacedouble=0;
52   PetscInt           an=A->cmap->N,am=A->rmap->N,pn=P->cmap->N,pm=P->rmap->N;
53   PetscInt           i,j,k,ptnzi,arow,anzj,ptanzi,prow,pnzj,cnzi,nlnk,*lnk;
54   MatScalar          *ca;
55   PetscBT            lnkbt;
56   PetscReal          afill;
57 
58   PetscFunctionBegin;
59   /* Get ij structure of P^T */
60   ierr = MatGetSymbolicTranspose_SeqAIJ(P,&pti,&ptj);CHKERRQ(ierr);
61   ptJ  = ptj;
62 
63   /* Allocate ci array, arrays for fill computation and */
64   /* free space for accumulating nonzero column info */
65   ierr  = PetscMalloc((pn+1)*sizeof(PetscInt),&ci);CHKERRQ(ierr);
66   ci[0] = 0;
67 
68   ierr         = PetscMalloc((2*an+1)*sizeof(PetscInt),&ptadenserow);CHKERRQ(ierr);
69   ierr         = PetscMemzero(ptadenserow,(2*an+1)*sizeof(PetscInt));CHKERRQ(ierr);
70   ptasparserow = ptadenserow  + an;
71 
72   /* create and initialize a linked list */
73   nlnk = pn+1;
74   ierr = PetscLLCreate(pn,pn,nlnk,lnk,lnkbt);CHKERRQ(ierr);
75 
76   /* Set initial free space to be fill*(nnz(A)+ nnz(P)) */
77   ierr          = PetscFreeSpaceGet((PetscInt)(fill*(ai[am]+pi[pm])),&free_space);CHKERRQ(ierr);
78   current_space = free_space;
79 
80   /* Determine symbolic info for each row of C: */
81   for (i=0; i<pn; i++) {
82     ptnzi  = pti[i+1] - pti[i];
83     ptanzi = 0;
84     /* Determine symbolic row of PtA: */
85     for (j=0; j<ptnzi; j++) {
86       arow = *ptJ++;
87       anzj = ai[arow+1] - ai[arow];
88       ajj  = aj + ai[arow];
89       for (k=0; k<anzj; k++) {
90         if (!ptadenserow[ajj[k]]) {
91           ptadenserow[ajj[k]]    = -1;
92           ptasparserow[ptanzi++] = ajj[k];
93         }
94       }
95     }
96     /* Using symbolic info for row of PtA, determine symbolic info for row of C: */
97     ptaj = ptasparserow;
98     cnzi = 0;
99     for (j=0; j<ptanzi; j++) {
100       prow = *ptaj++;
101       pnzj = pi[prow+1] - pi[prow];
102       pjj  = pj + pi[prow];
103       /* add non-zero cols of P into the sorted linked list lnk */
104       ierr  = PetscLLAddSorted(pnzj,pjj,pn,nlnk,lnk,lnkbt);CHKERRQ(ierr);
105       cnzi += nlnk;
106     }
107 
108     /* If free space is not available, make more free space */
109     /* Double the amount of total space in the list */
110     if (current_space->local_remaining<cnzi) {
111       ierr = PetscFreeSpaceGet(cnzi+current_space->total_array_size,&current_space);CHKERRQ(ierr);
112       nspacedouble++;
113     }
114 
115     /* Copy data into free space, and zero out denserows */
116     ierr = PetscLLClean(pn,pn,cnzi,lnk,current_space->array,lnkbt);CHKERRQ(ierr);
117 
118     current_space->array           += cnzi;
119     current_space->local_used      += cnzi;
120     current_space->local_remaining -= cnzi;
121 
122     for (j=0; j<ptanzi; j++) ptadenserow[ptasparserow[j]] = 0;
123 
124     /* Aside: Perhaps we should save the pta info for the numerical factorization. */
125     /*        For now, we will recompute what is needed. */
126     ci[i+1] = ci[i] + cnzi;
127   }
128   /* nnz is now stored in ci[ptm], column indices are in the list of free space */
129   /* Allocate space for cj, initialize cj, and */
130   /* destroy list of free space and other temporary array(s) */
131   ierr = PetscMalloc((ci[pn]+1)*sizeof(PetscInt),&cj);CHKERRQ(ierr);
132   ierr = PetscFreeSpaceContiguous(&free_space,cj);CHKERRQ(ierr);
133   ierr = PetscFree(ptadenserow);CHKERRQ(ierr);
134   ierr = PetscLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
135 
136   /* Allocate space for ca */
137   ierr = PetscMalloc((ci[pn]+1)*sizeof(MatScalar),&ca);CHKERRQ(ierr);
138   ierr = PetscMemzero(ca,(ci[pn]+1)*sizeof(MatScalar));CHKERRQ(ierr);
139 
140   /* put together the new matrix */
141   ierr = MatCreateSeqAIJWithArrays(PetscObjectComm((PetscObject)A),pn,pn,ci,cj,ca,C);CHKERRQ(ierr);
142 
143   (*C)->rmap->bs = P->cmap->bs;
144   (*C)->cmap->bs = P->cmap->bs;
145 
146   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
147   /* Since these are PETSc arrays, change flags to free them as necessary. */
148   c          = (Mat_SeqAIJ*)((*C)->data);
149   c->free_a  = PETSC_TRUE;
150   c->free_ij = PETSC_TRUE;
151   c->nonew   = 0;
152   (*C)->ops->ptapnumeric = MatPtAPNumeric_SeqAIJ_SeqAIJ_SparseAxpy;
153 
154   /* set MatInfo */
155   afill = (PetscReal)ci[pn]/(ai[am]+pi[pm] + 1.e-5);
156   if (afill < 1.0) afill = 1.0;
157   c->maxnz                     = ci[pn];
158   c->nz                        = ci[pn];
159   (*C)->info.mallocs           = nspacedouble;
160   (*C)->info.fill_ratio_given  = fill;
161   (*C)->info.fill_ratio_needed = afill;
162 
163   /* Clean up. */
164   ierr = MatRestoreSymbolicTranspose_SeqAIJ(P,&pti,&ptj);CHKERRQ(ierr);
165 #if defined(PETSC_USE_INFO)
166   if (ci[pn] != 0) {
167     ierr = PetscInfo3((*C),"Reallocs %D; Fill ratio: given %G needed %G.\n",nspacedouble,fill,afill);CHKERRQ(ierr);
168     ierr = PetscInfo1((*C),"Use MatPtAP(A,P,MatReuse,%G,&C) for best performance.\n",afill);CHKERRQ(ierr);
169   } else {
170     ierr = PetscInfo((*C),"Empty matrix product\n");CHKERRQ(ierr);
171   }
172 #endif
173   PetscFunctionReturn(0);
174 }
175 
176 #undef __FUNCT__
177 #define __FUNCT__ "MatPtAPNumeric_SeqAIJ_SeqAIJ_SparseAxpy"
178 PetscErrorCode MatPtAPNumeric_SeqAIJ_SeqAIJ_SparseAxpy(Mat A,Mat P,Mat C)
179 {
180   PetscErrorCode ierr;
181   Mat_SeqAIJ     *a = (Mat_SeqAIJ*) A->data;
182   Mat_SeqAIJ     *p = (Mat_SeqAIJ*) P->data;
183   Mat_SeqAIJ     *c = (Mat_SeqAIJ*) C->data;
184   PetscInt       *ai=a->i,*aj=a->j,*apj,*apjdense,*pi=p->i,*pj=p->j,*pJ=p->j,*pjj;
185   PetscInt       *ci=c->i,*cj=c->j,*cjj;
186   PetscInt       am =A->rmap->N,cn=C->cmap->N,cm=C->rmap->N;
187   PetscInt       i,j,k,anzi,pnzi,apnzj,nextap,pnzj,prow,crow;
188   MatScalar      *aa=a->a,*apa,*pa=p->a,*pA=p->a,*paj,*ca=c->a,*caj;
189 
190   PetscFunctionBegin;
191   /* Allocate temporary array for storage of one row of A*P (cn: non-scalable) */
192   ierr = PetscMalloc(cn*(sizeof(MatScalar)+sizeof(PetscInt))+c->rmax*sizeof(PetscInt),&apa);CHKERRQ(ierr);
193 
194   apjdense = (PetscInt*)(apa + cn);
195   apj      = apjdense + cn;
196   ierr     = PetscMemzero(apa,cn*(sizeof(MatScalar)+sizeof(PetscInt)));CHKERRQ(ierr);
197 
198   /* Clear old values in C */
199   ierr = PetscMemzero(ca,ci[cm]*sizeof(MatScalar));CHKERRQ(ierr);
200 
201   for (i=0; i<am; i++) {
202     /* Form sparse row of A*P */
203     anzi  = ai[i+1] - ai[i];
204     apnzj = 0;
205     for (j=0; j<anzi; j++) {
206       prow = *aj++;
207       pnzj = pi[prow+1] - pi[prow];
208       pjj  = pj + pi[prow];
209       paj  = pa + pi[prow];
210       for (k=0; k<pnzj; k++) {
211         if (!apjdense[pjj[k]]) {
212           apjdense[pjj[k]] = -1;
213           apj[apnzj++]     = pjj[k];
214         }
215         apa[pjj[k]] += (*aa)*paj[k];
216       }
217       ierr = PetscLogFlops(2.0*pnzj);CHKERRQ(ierr);
218       aa++;
219     }
220 
221     /* Sort the j index array for quick sparse axpy. */
222     /* Note: a array does not need sorting as it is in dense storage locations. */
223     ierr = PetscSortInt(apnzj,apj);CHKERRQ(ierr);
224 
225     /* Compute P^T*A*P using outer product (P^T)[:,j]*(A*P)[j,:]. */
226     pnzi = pi[i+1] - pi[i];
227     for (j=0; j<pnzi; j++) {
228       nextap = 0;
229       crow   = *pJ++;
230       cjj    = cj + ci[crow];
231       caj    = ca + ci[crow];
232       /* Perform sparse axpy operation.  Note cjj includes apj. */
233       for (k=0; nextap<apnzj; k++) {
234 #if defined(PETSC_USE_DEBUG)
235         if (k >= ci[crow+1] - ci[crow]) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_PLIB,"k too large k %d, crow %d",k,crow);
236 #endif
237         if (cjj[k]==apj[nextap]) {
238           caj[k] += (*pA)*apa[apj[nextap++]];
239         }
240       }
241       ierr = PetscLogFlops(2.0*apnzj);CHKERRQ(ierr);
242       pA++;
243     }
244 
245     /* Zero the current row info for A*P */
246     for (j=0; j<apnzj; j++) {
247       apa[apj[j]]      = 0.;
248       apjdense[apj[j]] = 0;
249     }
250   }
251 
252   /* Assemble the final matrix and clean up */
253   ierr = MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
254   ierr = MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
255 
256   ierr = PetscFree(apa);CHKERRQ(ierr);
257   PetscFunctionReturn(0);
258 }
259 
260 #undef __FUNCT__
261 #define __FUNCT__ "MatPtAPSymbolic_SeqAIJ_SeqAIJ"
262 PetscErrorCode MatPtAPSymbolic_SeqAIJ_SeqAIJ(Mat A,Mat P,PetscReal fill,Mat *C)
263 {
264   PetscErrorCode ierr;
265   Mat_SeqAIJ     *ap,*c;
266   PetscInt       *api,*apj,*ci,pn=P->cmap->N;
267   MatScalar      *ca;
268   Mat_PtAP       *ptap;
269   Mat            Pt,AP;
270   PetscBool      sparse_axpy=PETSC_TRUE;
271 
272   PetscFunctionBegin;
273   ierr = PetscObjectOptionsBegin((PetscObject)A);CHKERRQ(ierr);
274   /* flag 'sparse_axpy' determines which implementations to be used:
275        0: do dense axpy in MatPtAPNumeric() - fastest, but requires storage of struct A*P;
276        1: do two sparse axpy in MatPtAPNumeric() - slowest, does not store structure of A*P. */
277   ierr = PetscOptionsBool("-matptap_scalable","Use sparse axpy but slower MatPtAPNumeric()","",sparse_axpy,&sparse_axpy,NULL);CHKERRQ(ierr);
278   ierr = PetscOptionsEnd();CHKERRQ(ierr);
279   if (sparse_axpy) {
280     ierr = MatPtAPSymbolic_SeqAIJ_SeqAIJ_SparseAxpy(A,P,fill,C);CHKERRQ(ierr);
281     PetscFunctionReturn(0);
282   }
283 
284   /* Get symbolic Pt = P^T */
285   ierr = MatTransposeSymbolic_SeqAIJ(P,&Pt);CHKERRQ(ierr);
286 
287   /* Get symbolic AP = A*P */
288   ierr = MatMatMultSymbolic_SeqAIJ_SeqAIJ(A,P,fill,&AP);CHKERRQ(ierr);
289 
290   ap          = (Mat_SeqAIJ*)AP->data;
291   api         = ap->i;
292   apj         = ap->j;
293   ap->free_ij = PETSC_FALSE; /* api and apj are kept in struct ptap, cannot be destroyed with AP */
294 
295   /* Get C = Pt*AP */
296   ierr = MatMatMultSymbolic_SeqAIJ_SeqAIJ(Pt,AP,fill,C);CHKERRQ(ierr);
297 
298   c         = (Mat_SeqAIJ*)(*C)->data;
299   ci        = c->i;
300   ierr      = PetscMalloc((ci[pn]+1)*sizeof(MatScalar),&ca);CHKERRQ(ierr);
301   ierr      = PetscMemzero(ca,(ci[pn]+1)*sizeof(MatScalar));CHKERRQ(ierr);
302   c->a      = ca;
303   c->free_a = PETSC_TRUE;
304 
305   /* Create a supporting struct for reuse by MatPtAPNumeric() */
306   ierr = PetscNew(Mat_PtAP,&ptap);CHKERRQ(ierr);
307 
308   c->ptap            = ptap;
309   ptap->destroy      = (*C)->ops->destroy;
310   (*C)->ops->destroy = MatDestroy_SeqAIJ_PtAP;
311 
312   /* Allocate temporary array for storage of one row of A*P */
313   ierr = PetscMalloc((pn+1)*sizeof(PetscScalar),&ptap->apa);CHKERRQ(ierr);
314   ierr = PetscMemzero(ptap->apa,(pn+1)*sizeof(PetscScalar));CHKERRQ(ierr);
315 
316   (*C)->ops->ptapnumeric = MatPtAPNumeric_SeqAIJ_SeqAIJ;
317 
318   ptap->api = api;
319   ptap->apj = apj;
320 
321   /* Clean up. */
322   ierr = MatDestroy(&Pt);CHKERRQ(ierr);
323   ierr = MatDestroy(&AP);CHKERRQ(ierr);
324 #if defined(PETSC_USE_INFO)
325   ierr = PetscInfo2((*C),"given fill %G, use scalable %d\n",fill,sparse_axpy);CHKERRQ(ierr);
326 #endif
327   PetscFunctionReturn(0);
328 }
329 
330 /* #define PROFILE_MatPtAPNumeric */
331 #undef __FUNCT__
332 #define __FUNCT__ "MatPtAPNumeric_SeqAIJ_SeqAIJ"
333 PetscErrorCode MatPtAPNumeric_SeqAIJ_SeqAIJ(Mat A,Mat P,Mat C)
334 {
335   PetscErrorCode    ierr;
336   Mat_SeqAIJ        *a = (Mat_SeqAIJ*) A->data;
337   Mat_SeqAIJ        *p = (Mat_SeqAIJ*) P->data;
338   Mat_SeqAIJ        *c = (Mat_SeqAIJ*) C->data;
339   const PetscInt    *ai=a->i,*aj=a->j,*pi=p->i,*pj=p->j,*ci=c->i,*cj=c->j;
340   const PetscScalar *aa=a->a,*pa=p->a,*pval;
341   const PetscInt    *apj,*pcol,*cjj;
342   const PetscInt    am=A->rmap->N,cm=C->rmap->N;
343   PetscInt          i,j,k,anz,apnz,pnz,prow,crow,cnz;
344   PetscScalar       *apa,*ca=c->a,*caj,pvalj;
345   Mat_PtAP          *ptap = c->ptap;
346 #if defined(PROFILE_MatPtAPNumeric)
347   PetscLogDouble t0,tf,time_Cseq0=0.0,time_Cseq1=0.0;
348   PetscInt       flops0=0,flops1=0;
349 #endif
350 
351   PetscFunctionBegin;
352   /* Get temporary array for storage of one row of A*P */
353   apa = ptap->apa;
354 
355   /* Clear old values in C */
356   ierr = PetscMemzero(ca,ci[cm]*sizeof(MatScalar));CHKERRQ(ierr);
357 
358   for (i=0; i<am; i++) {
359     /* Form sparse row of AP[i,:] = A[i,:]*P */
360 #if defined(PROFILE_MatPtAPNumeric)
361     ierr = PetscTime(&t0);CHKERRQ(ierr);
362 #endif
363     anz  = ai[i+1] - ai[i];
364     apnz = 0;
365     for (j=0; j<anz; j++) {
366       prow = aj[j];
367       pnz  = pi[prow+1] - pi[prow];
368       pcol = pj + pi[prow];
369       pval = pa + pi[prow];
370       for (k=0; k<pnz; k++) {
371         apa[pcol[k]] += aa[j]*pval[k];
372       }
373       ierr = PetscLogFlops(2.0*pnz);CHKERRQ(ierr);
374 #if defined(PROFILE_MatPtAPNumeric)
375       flops0 += 2.0*pnz;
376 #endif
377     }
378     aj += anz; aa += anz;
379 #if defined(PROFILE_MatPtAPNumeric)
380     ierr = PetscTime(&tf);CHKERRQ(ierr);
381 
382     time_Cseq0 += tf - t0;
383 #endif
384 
385     /* Compute P^T*A*P using outer product P[i,:]^T*AP[i,:]. */
386 #if defined(PROFILE_MatPtAPNumeric)
387     ierr = PetscTime(&t0);CHKERRQ(ierr);
388 #endif
389     apj  = ptap->apj + ptap->api[i];
390     apnz = ptap->api[i+1] - ptap->api[i];
391     pnz  = pi[i+1] - pi[i];
392     pcol = pj + pi[i];
393     pval = pa + pi[i];
394 
395     /* Perform dense axpy */
396     for (j=0; j<pnz; j++) {
397       crow  = pcol[j];
398       cjj   = cj + ci[crow];
399       caj   = ca + ci[crow];
400       pvalj = pval[j];
401       cnz   = ci[crow+1] - ci[crow];
402       for (k=0; k<cnz; k++) caj[k] += pvalj*apa[cjj[k]];
403       ierr = PetscLogFlops(2.0*cnz);CHKERRQ(ierr);
404 #if defined(PROFILE_MatPtAPNumeric)
405       flops1 += 2.0*cnz;
406 #endif
407     }
408 #if defined(PROFILE_MatPtAPNumeric)
409     ierr        = PetscTime(&tf);CHKERRQ(ierr);
410     time_Cseq1 += tf - t0;
411 #endif
412 
413     /* Zero the current row info for A*P */
414     for (j=0; j<apnz; j++) apa[apj[j]] = 0.0;
415   }
416 
417   /* Assemble the final matrix and clean up */
418   ierr = MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
419   ierr = MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
420 #if defined(PROFILE_MatPtAPNumeric)
421   printf("PtAPNumeric_SeqAIJ time %g + %g, flops %d %d\n",time_Cseq0,time_Cseq1,flops0,flops1);
422 #endif
423   PetscFunctionReturn(0);
424 }
425