xref: /petsc/src/mat/impls/aij/seq/matptap.c (revision e383bbd07f1c175fdb04eea9fdcaf8d9f9e92c0f)
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 
11 #undef __FUNCT__
12 #define __FUNCT__ "MatPtAP_SeqAIJ_SeqAIJ"
13 PetscErrorCode MatPtAP_SeqAIJ_SeqAIJ(Mat A,Mat P,MatReuse scall,PetscReal fill,Mat *C)
14 {
15   PetscErrorCode ierr;
16 
17   PetscFunctionBegin;
18   if (scall == MAT_INITIAL_MATRIX){
19     ierr = PetscLogEventBegin(MAT_PtAPSymbolic,A,P,0,0);CHKERRQ(ierr);
20     ierr = MatPtAPSymbolic_SeqAIJ_SeqAIJ(A,P,fill,C);CHKERRQ(ierr);
21     ierr = PetscLogEventEnd(MAT_PtAPSymbolic,A,P,0,0);CHKERRQ(ierr);
22   }
23   ierr = PetscLogEventBegin(MAT_PtAPNumeric,A,P,0,0);CHKERRQ(ierr);
24   ierr = (*(*C)->ops->ptapnumeric)(A,P,*C);CHKERRQ(ierr);
25   ierr = PetscLogEventEnd(MAT_PtAPNumeric,A,P,0,0);CHKERRQ(ierr);
26   PetscFunctionReturn(0);
27 }
28 
29 #undef __FUNCT__
30 #define __FUNCT__ "MatDestroy_SeqAIJ_PtAP"
31 PetscErrorCode MatDestroy_SeqAIJ_PtAP(Mat A)
32 {
33   PetscErrorCode ierr;
34   Mat_SeqAIJ     *a = (Mat_SeqAIJ *)A->data;
35   Mat_PtAP       *ptap = a->ptap;
36 
37   PetscFunctionBegin;
38   ierr = PetscFree(ptap->apa);CHKERRQ(ierr);
39   ierr = PetscFree(ptap->api);CHKERRQ(ierr);
40   ierr = PetscFree(ptap->apj);CHKERRQ(ierr);
41   ierr = (ptap->destroy)(A);CHKERRQ(ierr);
42   ierr = PetscFree(ptap);CHKERRQ(ierr);
43   PetscFunctionReturn(0);
44 }
45 
46 #undef __FUNCT__
47 #define __FUNCT__ "MatPtAPSymbolic_SeqAIJ_SeqAIJ_SparseAxpy"
48 PetscErrorCode MatPtAPSymbolic_SeqAIJ_SeqAIJ_SparseAxpy(Mat A,Mat P,PetscReal fill,Mat *C)
49 {
50   PetscErrorCode     ierr;
51   PetscFreeSpaceList free_space=PETSC_NULL,current_space=PETSC_NULL;
52   Mat_SeqAIJ         *a = (Mat_SeqAIJ*)A->data,*p = (Mat_SeqAIJ*)P->data,*c;
53   PetscInt           *pti,*ptj,*ptJ,*ai=a->i,*aj=a->j,*ajj,*pi=p->i,*pj=p->j,*pjj;
54   PetscInt           *ci,*cj,*ptadenserow,*ptasparserow,*ptaj,nspacedouble=0;
55   PetscInt           an=A->cmap->N,am=A->rmap->N,pn=P->cmap->N;
56   PetscInt           i,j,k,ptnzi,arow,anzj,ptanzi,prow,pnzj,cnzi,nlnk,*lnk;
57   MatScalar          *ca;
58   PetscBT            lnkbt;
59 
60   PetscFunctionBegin;
61   /* Get ij structure of P^T */
62   ierr = MatGetSymbolicTranspose_SeqAIJ(P,&pti,&ptj);CHKERRQ(ierr);
63   ptJ=ptj;
64 
65   /* Allocate ci array, arrays for fill computation and */
66   /* free space for accumulating nonzero column info */
67   ierr = PetscMalloc((pn+1)*sizeof(PetscInt),&ci);CHKERRQ(ierr);
68   ci[0] = 0;
69 
70   ierr = PetscMalloc((2*an+1)*sizeof(PetscInt),&ptadenserow);CHKERRQ(ierr);
71   ierr = PetscMemzero(ptadenserow,(2*an+1)*sizeof(PetscInt));CHKERRQ(ierr);
72   ptasparserow = ptadenserow  + an;
73 
74   /* create and initialize a linked list */
75   nlnk = pn+1;
76   ierr = PetscLLCreate(pn,pn,nlnk,lnk,lnkbt);CHKERRQ(ierr);
77 
78   /* Set initial free space to be fill*nnz(A). */
79   /* This should be reasonable if sparsity of PtAP is similar to that of A. */
80   ierr          = PetscFreeSpaceGet((PetscInt)(fill*ai[am]),&free_space);CHKERRQ(ierr);
81   current_space = free_space;
82 
83   /* Determine symbolic info for each row of C: */
84   for (i=0;i<pn;i++) {
85     ptnzi  = pti[i+1] - pti[i];
86     ptanzi = 0;
87     /* Determine symbolic row of PtA: */
88     for (j=0;j<ptnzi;j++) {
89       arow = *ptJ++;
90       anzj = ai[arow+1] - ai[arow];
91       ajj  = aj + ai[arow];
92       for (k=0;k<anzj;k++) {
93         if (!ptadenserow[ajj[k]]) {
94           ptadenserow[ajj[k]]    = -1;
95           ptasparserow[ptanzi++] = ajj[k];
96         }
97       }
98     }
99     /* Using symbolic info for row of PtA, determine symbolic info for row of C: */
100     ptaj = ptasparserow;
101     cnzi   = 0;
102     for (j=0;j<ptanzi;j++) {
103       prow = *ptaj++;
104       pnzj = pi[prow+1] - pi[prow];
105       pjj  = pj + pi[prow];
106       /* add non-zero cols of P into the sorted linked list lnk */
107       ierr = PetscLLAddSorted(pnzj,pjj,pn,nlnk,lnk,lnkbt);CHKERRQ(ierr);
108       cnzi += nlnk;
109     }
110 
111     /* If free space is not available, make more free space */
112     /* Double the amount of total space in the list */
113     if (current_space->local_remaining<cnzi) {
114       ierr = PetscFreeSpaceGet(cnzi+current_space->total_array_size,&current_space);CHKERRQ(ierr);
115       nspacedouble++;
116     }
117 
118     /* Copy data into free space, and zero out denserows */
119     ierr = PetscLLClean(pn,pn,cnzi,lnk,current_space->array,lnkbt);CHKERRQ(ierr);
120     current_space->array           += cnzi;
121     current_space->local_used      += cnzi;
122     current_space->local_remaining -= cnzi;
123 
124     for (j=0;j<ptanzi;j++) {
125       ptadenserow[ptasparserow[j]] = 0;
126     }
127     /* Aside: Perhaps we should save the pta info for the numerical factorization. */
128     /*        For now, we will recompute what is needed. */
129     ci[i+1] = ci[i] + cnzi;
130   }
131   /* nnz is now stored in ci[ptm], column indices are in the list of free space */
132   /* Allocate space for cj, initialize cj, and */
133   /* destroy list of free space and other temporary array(s) */
134   ierr = PetscMalloc((ci[pn]+1)*sizeof(PetscInt),&cj);CHKERRQ(ierr);
135   ierr = PetscFreeSpaceContiguous(&free_space,cj);CHKERRQ(ierr);
136   ierr = PetscFree(ptadenserow);CHKERRQ(ierr);
137   ierr = PetscLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
138 
139   /* Allocate space for ca */
140   ierr = PetscMalloc((ci[pn]+1)*sizeof(MatScalar),&ca);CHKERRQ(ierr);
141   ierr = PetscMemzero(ca,(ci[pn]+1)*sizeof(MatScalar));CHKERRQ(ierr);
142 
143   /* put together the new matrix */
144   ierr = MatCreateSeqAIJWithArrays(((PetscObject)A)->comm,pn,pn,ci,cj,ca,C);CHKERRQ(ierr);
145   (*C)->rmap->bs = P->cmap->bs;
146   (*C)->cmap->bs = P->cmap->bs;
147 
148   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
149   /* Since these are PETSc arrays, change flags to free them as necessary. */
150   c = (Mat_SeqAIJ *)((*C)->data);
151   c->free_a  = PETSC_TRUE;
152   c->free_ij = PETSC_TRUE;
153   c->nonew   = 0;
154   (*C)->ops->ptapnumeric = MatPtAPNumeric_SeqAIJ_SeqAIJ_SparseAxpy;
155 
156   /* Clean up. */
157   ierr = MatRestoreSymbolicTranspose_SeqAIJ(P,&pti,&ptj);CHKERRQ(ierr);
158 #if defined(PETSC_USE_INFO)
159   if (ci[pn] != 0) {
160     PetscReal afill = ((PetscReal)ci[pn])/ai[am];
161     if (afill < 1.0) afill = 1.0;
162     ierr = PetscInfo3((*C),"Reallocs %D; Fill ratio: given %G needed %G.\n",nspacedouble,fill,afill);CHKERRQ(ierr);
163     ierr = PetscInfo1((*C),"Use MatPtAP(A,P,MatReuse,%G,&C) for best performance.\n",afill);CHKERRQ(ierr);
164   } else {
165     ierr = PetscInfo((*C),"Empty matrix product\n");CHKERRQ(ierr);
166   }
167 #endif
168   PetscFunctionReturn(0);
169 }
170 
171 #undef __FUNCT__
172 #define __FUNCT__ "MatPtAPNumeric_SeqAIJ_SeqAIJ_SparseAxpy"
173 PetscErrorCode MatPtAPNumeric_SeqAIJ_SeqAIJ_SparseAxpy(Mat A,Mat P,Mat C)
174 {
175   PetscErrorCode ierr;
176   Mat_SeqAIJ     *a  = (Mat_SeqAIJ *) A->data;
177   Mat_SeqAIJ     *p  = (Mat_SeqAIJ *) P->data;
178   Mat_SeqAIJ     *c  = (Mat_SeqAIJ *) C->data;
179   PetscInt       *ai=a->i,*aj=a->j,*apj,*apjdense,*pi=p->i,*pj=p->j,*pJ=p->j,*pjj;
180   PetscInt       *ci=c->i,*cj=c->j,*cjj;
181   PetscInt       am=A->rmap->N,cn=C->cmap->N,cm=C->rmap->N;
182   PetscInt       i,j,k,anzi,pnzi,apnzj,nextap,pnzj,prow,crow;
183   MatScalar      *aa=a->a,*apa,*pa=p->a,*pA=p->a,*paj,*ca=c->a,*caj;
184 
185   PetscFunctionBegin;
186   /* Allocate temporary array for storage of one row of A*P (cn: non-scalable) */
187   ierr = PetscMalloc(cn*(sizeof(MatScalar)+sizeof(PetscInt))+c->rmax*sizeof(PetscInt),&apa);CHKERRQ(ierr);
188 
189   apjdense = (PetscInt *)(apa + cn);
190   apj      = apjdense + cn;
191   ierr = PetscMemzero(apa,cn*(sizeof(MatScalar)+sizeof(PetscInt)));CHKERRQ(ierr);
192 
193   /* Clear old values in C */
194   ierr = PetscMemzero(ca,ci[cm]*sizeof(MatScalar));CHKERRQ(ierr);
195 
196   for (i=0; i<am; i++) {
197     /* Form sparse row of A*P */
198     anzi  = ai[i+1] - ai[i];
199     apnzj = 0;
200     for (j=0; j<anzi; j++) {
201       prow = *aj++;
202       pnzj = pi[prow+1] - pi[prow];
203       pjj  = pj + pi[prow];
204       paj  = pa + pi[prow];
205       for (k=0;k<pnzj;k++) {
206         if (!apjdense[pjj[k]]) {
207           apjdense[pjj[k]] = -1;
208           apj[apnzj++]     = pjj[k];
209         }
210         apa[pjj[k]] += (*aa)*paj[k];
211       }
212       ierr = PetscLogFlops(2.0*pnzj);CHKERRQ(ierr);
213       aa++;
214     }
215 
216     /* Sort the j index array for quick sparse axpy. */
217     /* Note: a array does not need sorting as it is in dense storage locations. */
218     ierr = PetscSortInt(apnzj,apj);CHKERRQ(ierr);
219 
220     /* Compute P^T*A*P using outer product (P^T)[:,j]*(A*P)[j,:]. */
221     pnzi = pi[i+1] - pi[i];
222     for (j=0; j<pnzi; j++) {
223       nextap = 0;
224       crow   = *pJ++;
225       cjj    = cj + ci[crow];
226       caj    = ca + ci[crow];
227       /* Perform sparse axpy operation.  Note cjj includes apj. */
228       for (k=0;nextap<apnzj;k++) {
229 #if defined(PETSC_USE_DEBUG)
230         if (k >= ci[crow+1] - ci[crow]) {
231           SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_PLIB,"k too large k %d, crow %d",k,crow);
232         }
233 #endif
234         if (cjj[k]==apj[nextap]) {
235           caj[k] += (*pA)*apa[apj[nextap++]];
236         }
237       }
238       ierr = PetscLogFlops(2.0*apnzj);CHKERRQ(ierr);
239       pA++;
240     }
241 
242     /* Zero the current row info for A*P */
243     for (j=0; j<apnzj; j++) {
244       apa[apj[j]]      = 0.;
245       apjdense[apj[j]] = 0;
246     }
247   }
248 
249   /* Assemble the final matrix and clean up */
250   ierr = MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
251   ierr = MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
252 
253   ierr = PetscFree(apa);CHKERRQ(ierr);
254   PetscFunctionReturn(0);
255 }
256 
257 #undef __FUNCT__
258 #define __FUNCT__ "MatPtAPSymbolic_SeqAIJ_SeqAIJ"
259 PetscErrorCode MatPtAPSymbolic_SeqAIJ_SeqAIJ(Mat A,Mat P,PetscReal fill,Mat *C)
260 {
261   PetscErrorCode     ierr;
262   Mat_SeqAIJ         *ap,*c;
263   PetscInt           *api,*apj,*ci,pn=P->cmap->N;
264   MatScalar          *ca;
265   Mat_PtAP           *ptap;
266   Mat                Pt,AP;
267   PetscBool          sparse_axpy=PETSC_TRUE;
268 
269   PetscFunctionBegin;
270   ierr = PetscObjectOptionsBegin((PetscObject)A);CHKERRQ(ierr);
271   /* flag 'sparse_axpy' determines which implementations to be used:
272        0: do dense axpy in MatPtAPNumeric() - fastest, but requires storage of struct A*P;
273        1: do two sparse axpy in MatPtAPNumeric() - slowest, does not store structure of A*P. */
274   ierr = PetscOptionsBool("-matptap_scalable","Use sparse axpy but slower MatPtAPNumeric()","",sparse_axpy,&sparse_axpy,PETSC_NULL);CHKERRQ(ierr);
275   ierr = PetscOptionsEnd();CHKERRQ(ierr);
276   if (sparse_axpy){
277     ierr = MatPtAPSymbolic_SeqAIJ_SeqAIJ_SparseAxpy(A,P,fill,C);CHKERRQ(ierr);
278     PetscFunctionReturn(0);
279   }
280 
281   /* Get symbolic Pt = P^T */
282   ierr = MatTransposeSymbolic_SeqAIJ(P,&Pt);CHKERRQ(ierr);
283 
284   /* Get symbolic AP = A*P */
285   ierr = MatMatMultSymbolic_SeqAIJ_SeqAIJ(A,P,fill,&AP);CHKERRQ(ierr);
286 
287   ap          = (Mat_SeqAIJ*)AP->data;
288   api         = ap->i;
289   apj         = ap->j;
290   ap->free_ij = PETSC_FALSE; /* api and apj are kept in struct ptap, cannot be destroyed with AP */
291 
292   /* Get C = Pt*AP */
293   ierr = MatMatMultSymbolic_SeqAIJ_SeqAIJ(Pt,AP,fill,C);CHKERRQ(ierr);
294 
295   c  = (Mat_SeqAIJ*)(*C)->data;
296   ci = c->i;
297   ierr = PetscMalloc((ci[pn]+1)*sizeof(MatScalar),&ca);CHKERRQ(ierr);
298   ierr = PetscMemzero(ca,(ci[pn]+1)*sizeof(MatScalar));CHKERRQ(ierr);
299   c->a       = ca;
300   c->free_a  = PETSC_TRUE;
301 
302   /* Create a supporting struct for reuse by MatPtAPNumeric() */
303   ierr = PetscNew(Mat_PtAP,&ptap);CHKERRQ(ierr);
304   c->ptap            = ptap;
305   ptap->destroy      = (*C)->ops->destroy;
306   (*C)->ops->destroy = MatDestroy_SeqAIJ_PtAP;
307 
308   /* Allocate temporary array for storage of one row of A*P */
309   ierr = PetscMalloc((pn+1)*sizeof(PetscScalar),&ptap->apa);CHKERRQ(ierr);
310   ierr = PetscMemzero(ptap->apa,(pn+1)*sizeof(PetscScalar));CHKERRQ(ierr);
311   (*C)->ops->ptapnumeric = MatPtAPNumeric_SeqAIJ_SeqAIJ;
312 
313   ptap->api = api;
314   ptap->apj = apj;
315 
316   /* Clean up. */
317   ierr = MatDestroy(&Pt);CHKERRQ(ierr);
318   ierr = MatDestroy(&AP);CHKERRQ(ierr);
319 #if defined(PETSC_USE_INFO)
320   ierr = PetscInfo2((*C),"given fill %G, use scalable %d\n",fill,sparse_axpy);CHKERRQ(ierr);
321 #endif
322   PetscFunctionReturn(0);
323 }
324 
325 /* #define PROFILE_MatPtAPNumeric */
326 #undef __FUNCT__
327 #define __FUNCT__ "MatPtAPNumeric_SeqAIJ_SeqAIJ"
328 PetscErrorCode MatPtAPNumeric_SeqAIJ_SeqAIJ(Mat A,Mat P,Mat C)
329 {
330   PetscErrorCode    ierr;
331   Mat_SeqAIJ        *a  = (Mat_SeqAIJ *) A->data;
332   Mat_SeqAIJ        *p  = (Mat_SeqAIJ *) P->data;
333   Mat_SeqAIJ        *c  = (Mat_SeqAIJ *) C->data;
334   const PetscInt    *ai=a->i,*aj=a->j,*pi=p->i,*pj=p->j,*ci=c->i,*cj=c->j;
335   const PetscScalar *aa=a->a,*pa=p->a,*pval;
336   const PetscInt    *apj,*pcol,*cjj;
337   const PetscInt    am=A->rmap->N,cm=C->rmap->N;
338   PetscInt          i,j,k,anz,apnz,pnz,prow,crow,cnz;
339   PetscScalar       *apa,*ca=c->a,*caj,pvalj;
340   Mat_PtAP          *ptap = c->ptap;
341 #if defined(PROFILE_MatPtAPNumeric)
342   PetscLogDouble    t0,tf,time_Cseq0=0.0,time_Cseq1=0.0;
343   PetscInt          flops0=0,flops1=0;
344 #endif
345 
346   PetscFunctionBegin;
347   /* Get temporary array for storage of one row of A*P */
348   apa = ptap->apa;
349 
350   /* Clear old values in C */
351   ierr = PetscMemzero(ca,ci[cm]*sizeof(MatScalar));CHKERRQ(ierr);
352 
353   for (i=0;i<am;i++) {
354     /* Form sparse row of AP[i,:] = A[i,:]*P */
355 #if defined(PROFILE_MatPtAPNumeric)
356     ierr = PetscGetTime(&t0);CHKERRQ(ierr);
357 #endif
358     anz  = ai[i+1] - ai[i];
359     apnz = 0;
360     for (j=0; j<anz; j++) {
361       prow = aj[j];
362       pnz  = pi[prow+1] - pi[prow];
363       pcol = pj + pi[prow];
364       pval = pa + pi[prow];
365       for (k=0; k<pnz; k++) {
366         apa[pcol[k]] += aa[j]*pval[k];
367       }
368       ierr = PetscLogFlops(2.0*pnz);CHKERRQ(ierr);
369 #if defined(PROFILE_MatPtAPNumeric)
370       flops0 += 2.0*pnz;
371 #endif
372     }
373     aj += anz; aa += anz;
374 #if defined(PROFILE_MatPtAPNumeric)
375     ierr = PetscGetTime(&tf);CHKERRQ(ierr);
376     time_Cseq0 += tf - t0;
377 #endif
378 
379     /* Compute P^T*A*P using outer product P[i,:]^T*AP[i,:]. */
380 #if defined(PROFILE_MatPtAPNumeric)
381     ierr = PetscGetTime(&t0);CHKERRQ(ierr);
382 #endif
383     apj  = ptap->apj + ptap->api[i];
384     apnz = ptap->api[i+1] - ptap->api[i];
385     pnz  = pi[i+1] - pi[i];
386     pcol = pj + pi[i];
387     pval = pa + pi[i];
388 
389     /* Perform dense axpy */
390     for (j=0; j<pnz; j++) {
391       crow  = pcol[j];
392       cjj   = cj + ci[crow];
393       caj   = ca + ci[crow];
394       pvalj = pval[j];
395       cnz   = ci[crow+1] - ci[crow];
396       for (k=0; k<cnz; k++){
397         caj[k] += pvalj*apa[cjj[k]];
398       }
399       ierr = PetscLogFlops(2.0*cnz);CHKERRQ(ierr);
400 #if defined(PROFILE_MatPtAPNumeric)
401       flops1 += 2.0*cnz;
402 #endif
403     }
404 #if defined(PROFILE_MatPtAPNumeric)
405     ierr = PetscGetTime(&tf);CHKERRQ(ierr);
406     time_Cseq1 += tf - t0;
407 #endif
408 
409     /* Zero the current row info for A*P */
410     for (j=0; j<apnz; j++) apa[apj[j]] = 0.0;
411   }
412 
413   /* Assemble the final matrix and clean up */
414   ierr = MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
415   ierr = MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
416 #if defined(PROFILE_MatPtAPNumeric)
417   printf("PtAPNumeric_SeqAIJ time %g + %g, flops %d %d\n",time_Cseq0,time_Cseq1,flops0,flops1);
418 #endif
419   PetscFunctionReturn(0);
420 }
421