xref: /petsc/src/mat/impls/aij/seq/matptap.c (revision 7e6920316c442086e91a5c9dd43cefbf07f86e0c)
1 /*
2   Defines projective product routines where A is a SeqAIJ matrix
3           C = P^T * A * P
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 
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 = MatPtAPNumeric_SeqAIJ_SeqAIJ(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__ "MatPtAPSymbolic_SeqAIJ_SeqAIJ"
31 PetscErrorCode MatPtAPSymbolic_SeqAIJ_SeqAIJ(Mat A,Mat P,PetscReal fill,Mat *C)
32 {
33   PetscErrorCode ierr;
34   FreeSpaceList  free_space=PETSC_NULL,current_space=PETSC_NULL;
35   Mat_SeqAIJ     *a = (Mat_SeqAIJ*)A->data,*p = (Mat_SeqAIJ*)P->data,*c;
36   PetscInt       *pti,*ptj,*ptJ,*ai=a->i,*aj=a->j,*ajj,*pi=p->i,*pj=p->j,*pjj;
37   PetscInt       *ci,*cj,*ptadenserow,*ptasparserow,*ptaj;
38   PetscInt       an=A->N,am=A->M,pn=P->N,pm=P->M;
39   PetscInt       i,j,k,ptnzi,arow,anzj,ptanzi,prow,pnzj,cnzi,nlnk,*lnk;
40   MatScalar      *ca;
41   PetscBT        lnkbt;
42 
43   PetscFunctionBegin;
44   /* Get ij structure of P^T */
45   ierr = MatGetSymbolicTranspose_SeqAIJ(P,&pti,&ptj);CHKERRQ(ierr);
46   ptJ=ptj;
47 
48   /* Allocate ci array, arrays for fill computation and */
49   /* free space for accumulating nonzero column info */
50   ierr = PetscMalloc((pn+1)*sizeof(PetscInt),&ci);CHKERRQ(ierr);
51   ci[0] = 0;
52 
53   ierr = PetscMalloc((2*an+1)*sizeof(PetscInt),&ptadenserow);CHKERRQ(ierr);
54   ierr = PetscMemzero(ptadenserow,(2*an+1)*sizeof(PetscInt));CHKERRQ(ierr);
55   ptasparserow = ptadenserow  + an;
56 
57   /* create and initialize a linked list */
58   nlnk = pn+1;
59   ierr = PetscLLCreate(pn,pn,nlnk,lnk,lnkbt);CHKERRQ(ierr);
60 
61   /* Set initial free space to be nnz(A) scaled by aspect ratio of P. */
62   /* This should be reasonable if sparsity of PtAP is similar to that of A. */
63   ierr          = GetMoreSpace((ai[am]/pm)*pn,&free_space);
64   current_space = free_space;
65 
66   /* Determine symbolic info for each row of C: */
67   for (i=0;i<pn;i++) {
68     ptnzi  = pti[i+1] - pti[i];
69     ptanzi = 0;
70     /* Determine symbolic row of PtA: */
71     for (j=0;j<ptnzi;j++) {
72       arow = *ptJ++;
73       anzj = ai[arow+1] - ai[arow];
74       ajj  = aj + ai[arow];
75       for (k=0;k<anzj;k++) {
76         if (!ptadenserow[ajj[k]]) {
77           ptadenserow[ajj[k]]    = -1;
78           ptasparserow[ptanzi++] = ajj[k];
79         }
80       }
81     }
82       /* Using symbolic info for row of PtA, determine symbolic info for row of C: */
83     ptaj = ptasparserow;
84     cnzi   = 0;
85     for (j=0;j<ptanzi;j++) {
86       prow = *ptaj++;
87       pnzj = pi[prow+1] - pi[prow];
88       pjj  = pj + pi[prow];
89       /* add non-zero cols of P into the sorted linked list lnk */
90       ierr = PetscLLAdd(pnzj,pjj,pn,nlnk,lnk,lnkbt);CHKERRQ(ierr);
91       cnzi += nlnk;
92     }
93 
94     /* If free space is not available, make more free space */
95     /* Double the amount of total space in the list */
96     if (current_space->local_remaining<cnzi) {
97       ierr = GetMoreSpace(current_space->total_array_size,&current_space);CHKERRQ(ierr);
98     }
99 
100     /* Copy data into free space, and zero out denserows */
101     ierr = PetscLLClean(pn,pn,cnzi,lnk,current_space->array,lnkbt);CHKERRQ(ierr);
102     current_space->array           += cnzi;
103     current_space->local_used      += cnzi;
104     current_space->local_remaining -= cnzi;
105 
106     for (j=0;j<ptanzi;j++) {
107       ptadenserow[ptasparserow[j]] = 0;
108     }
109     /* Aside: Perhaps we should save the pta info for the numerical factorization. */
110     /*        For now, we will recompute what is needed. */
111     ci[i+1] = ci[i] + cnzi;
112   }
113   /* nnz is now stored in ci[ptm], column indices are in the list of free space */
114   /* Allocate space for cj, initialize cj, and */
115   /* destroy list of free space and other temporary array(s) */
116   ierr = PetscMalloc((ci[pn]+1)*sizeof(PetscInt),&cj);CHKERRQ(ierr);
117   ierr = MakeSpaceContiguous(&free_space,cj);CHKERRQ(ierr);
118   ierr = PetscFree(ptadenserow);CHKERRQ(ierr);
119   ierr = PetscLLDestroy(lnk,lnkbt);CHKERRQ(ierr);
120 
121   /* Allocate space for ca */
122   ierr = PetscMalloc((ci[pn]+1)*sizeof(MatScalar),&ca);CHKERRQ(ierr);
123   ierr = PetscMemzero(ca,(ci[pn]+1)*sizeof(MatScalar));CHKERRQ(ierr);
124 
125   /* put together the new matrix */
126   ierr = MatCreateSeqAIJWithArrays(A->comm,pn,pn,ci,cj,ca,C);CHKERRQ(ierr);
127 
128   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
129   /* Since these are PETSc arrays, change flags to free them as necessary. */
130   c = (Mat_SeqAIJ *)((*C)->data);
131   c->freedata = PETSC_TRUE;
132   c->nonew    = 0;
133 
134   /* Clean up. */
135   ierr = MatRestoreSymbolicTranspose_SeqAIJ(P,&pti,&ptj);CHKERRQ(ierr);
136 
137   PetscFunctionReturn(0);
138 }
139 
140 #include "src/mat/impls/maij/maij.h"
141 #undef __FUNCT__
142 #define __FUNCT__ "MatPtAPSymbolic_SeqAIJ_SeqMAIJ"
143 PetscErrorCode MatPtAPSymbolic_SeqAIJ_SeqMAIJ(Mat A,Mat PP,Mat *C)
144 {
145   /* This routine requires testing -- but it's getting better. */
146   PetscErrorCode ierr;
147   FreeSpaceList  free_space=PETSC_NULL,current_space=PETSC_NULL;
148   Mat_SeqMAIJ    *pp=(Mat_SeqMAIJ*)PP->data;
149   Mat            P=pp->AIJ;
150   Mat_SeqAIJ     *a=(Mat_SeqAIJ*)A->data,*p=(Mat_SeqAIJ*)P->data,*c;
151   PetscInt       *pti,*ptj,*ptJ,*ai=a->i,*aj=a->j,*ajj,*pi=p->i,*pj=p->j,*pjj;
152   PetscInt       *ci,*cj,*ptadenserow,*ptasparserow,*denserow,*sparserow,*ptaj;
153   PetscInt       an=A->N,am=A->M,pn=P->N,pm=P->M,ppdof=pp->dof,cn;
154   PetscInt       i,j,k,dof,pshift,ptnzi,arow,anzj,ptanzi,prow,pnzj,cnzi;
155   MatScalar      *ca;
156 
157   PetscFunctionBegin;
158   /* Start timer */
159   ierr = PetscLogEventBegin(MAT_PtAPSymbolic,A,PP,0,0);CHKERRQ(ierr);
160 
161   /* Get ij structure of P^T */
162   ierr = MatGetSymbolicTranspose_SeqAIJ(P,&pti,&ptj);CHKERRQ(ierr);
163 
164   cn = pn*ppdof;
165   /* Allocate ci array, arrays for fill computation and */
166   /* free space for accumulating nonzero column info */
167   ierr = PetscMalloc((cn+1)*sizeof(PetscInt),&ci);CHKERRQ(ierr);
168   ci[0] = 0;
169 
170   /* Work arrays for rows of P^T*A */
171   ierr = PetscMalloc((2*cn+2*an+1)*sizeof(PetscInt),&ptadenserow);CHKERRQ(ierr);
172   ierr = PetscMemzero(ptadenserow,(2*cn+2*an+1)*sizeof(PetscInt));CHKERRQ(ierr);
173   ptasparserow = ptadenserow  + an;
174   denserow     = ptasparserow + an;
175   sparserow    = denserow     + cn;
176 
177   /* Set initial free space to be nnz(A) scaled by aspect ratio of P. */
178   /* This should be reasonable if sparsity of PtAP is similar to that of A. */
179   /* Note, aspect ratio of P is the same as the aspect ratio of SeqAIJ inside P */
180   ierr          = GetMoreSpace((ai[am]/pm)*pn,&free_space);
181   current_space = free_space;
182 
183   /* Determine symbolic info for each row of C: */
184   for (i=0;i<pn;i++) {
185     ptnzi  = pti[i+1] - pti[i];
186     ptanzi = 0;
187     ptJ    = ptj + pti[i];
188     for (dof=0;dof<ppdof;dof++) {
189     /* Determine symbolic row of PtA: */
190       for (j=0;j<ptnzi;j++) {
191         /* Expand ptJ[j] by block size and shift by dof to get the right row of A */
192         arow = ptJ[j]*ppdof + dof;
193         /* Nonzeros of P^T*A will be in same locations as any element of A in that row */
194         anzj = ai[arow+1] - ai[arow];
195         ajj  = aj + ai[arow];
196         for (k=0;k<anzj;k++) {
197           if (!ptadenserow[ajj[k]]) {
198             ptadenserow[ajj[k]]    = -1;
199             ptasparserow[ptanzi++] = ajj[k];
200           }
201         }
202       }
203       /* Using symbolic info for row of PtA, determine symbolic info for row of C: */
204       ptaj = ptasparserow;
205       cnzi   = 0;
206       for (j=0;j<ptanzi;j++) {
207         /* Get offset within block of P */
208         pshift = *ptaj%ppdof;
209         /* Get block row of P */
210         prow = (*ptaj++)/ppdof;
211         /* P has same number of nonzeros per row as the compressed form */
212         pnzj = pi[prow+1] - pi[prow];
213         pjj  = pj + pi[prow];
214         for (k=0;k<pnzj;k++) {
215           /* Locations in C are shifted by the offset within the block */
216           if (!denserow[pjj[k]+pshift]) {
217             denserow[pjj[k]+pshift] = -1;
218             sparserow[cnzi++]     = pjj[k]+pshift;
219           }
220         }
221       }
222 
223       /* sort sparserow */
224       ierr = PetscSortInt(cnzi,sparserow);CHKERRQ(ierr);
225 
226       /* If free space is not available, make more free space */
227       /* Double the amount of total space in the list */
228       if (current_space->local_remaining<cnzi) {
229         ierr = GetMoreSpace(current_space->total_array_size,&current_space);CHKERRQ(ierr);
230       }
231 
232       /* Copy data into free space, and zero out denserows */
233       ierr = PetscMemcpy(current_space->array,sparserow,cnzi*sizeof(PetscInt));CHKERRQ(ierr);
234       current_space->array           += cnzi;
235       current_space->local_used      += cnzi;
236       current_space->local_remaining -= cnzi;
237 
238       for (j=0;j<ptanzi;j++) {
239         ptadenserow[ptasparserow[j]] = 0;
240       }
241       for (j=0;j<cnzi;j++) {
242         denserow[sparserow[j]] = 0;
243       }
244       /* Aside: Perhaps we should save the pta info for the numerical factorization. */
245       /*        For now, we will recompute what is needed. */
246       ci[i*ppdof+1+dof] = ci[i*ppdof+dof] + cnzi;
247     }
248   }
249   /* nnz is now stored in ci[ptm], column indices are in the list of free space */
250   /* Allocate space for cj, initialize cj, and */
251   /* destroy list of free space and other temporary array(s) */
252   ierr = PetscMalloc((ci[cn]+1)*sizeof(PetscInt),&cj);CHKERRQ(ierr);
253   ierr = MakeSpaceContiguous(&free_space,cj);CHKERRQ(ierr);
254   ierr = PetscFree(ptadenserow);CHKERRQ(ierr);
255 
256   /* Allocate space for ca */
257   ierr = PetscMalloc((ci[cn]+1)*sizeof(MatScalar),&ca);CHKERRQ(ierr);
258   ierr = PetscMemzero(ca,(ci[cn]+1)*sizeof(MatScalar));CHKERRQ(ierr);
259 
260   /* put together the new matrix */
261   ierr = MatCreateSeqAIJWithArrays(A->comm,cn,cn,ci,cj,ca,C);CHKERRQ(ierr);
262 
263   /* MatCreateSeqAIJWithArrays flags matrix so PETSc doesn't free the user's arrays. */
264   /* Since these are PETSc arrays, change flags to free them as necessary. */
265   c = (Mat_SeqAIJ *)((*C)->data);
266   c->freedata = PETSC_TRUE;
267   c->nonew    = 0;
268 
269   /* Clean up. */
270   ierr = MatRestoreSymbolicTranspose_SeqAIJ(P,&pti,&ptj);CHKERRQ(ierr);
271 
272   ierr = PetscLogEventEnd(MAT_PtAPSymbolic,A,PP,0,0);CHKERRQ(ierr);
273   PetscFunctionReturn(0);
274 }
275 
276 #undef __FUNCT__
277 #define __FUNCT__ "MatPtAPNumeric_SeqAIJ_SeqAIJ"
278 PetscErrorCode MatPtAPNumeric_SeqAIJ_SeqAIJ(Mat A,Mat P,Mat C)
279 {
280   PetscErrorCode ierr;
281   PetscInt       flops=0;
282   Mat_SeqAIJ     *a  = (Mat_SeqAIJ *) A->data;
283   Mat_SeqAIJ     *p  = (Mat_SeqAIJ *) P->data;
284   Mat_SeqAIJ     *c  = (Mat_SeqAIJ *) C->data;
285   PetscInt       *ai=a->i,*aj=a->j,*apj,*apjdense,*pi=p->i,*pj=p->j,*pJ=p->j,*pjj;
286   PetscInt       *ci=c->i,*cj=c->j,*cjj;
287   PetscInt       am=A->M,cn=C->N,cm=C->M;
288   PetscInt       i,j,k,anzi,pnzi,apnzj,nextap,pnzj,prow,crow;
289   MatScalar      *aa=a->a,*apa,*pa=p->a,*pA=p->a,*paj,*ca=c->a,*caj;
290 
291   PetscFunctionBegin;
292   /* Allocate temporary array for storage of one row of A*P */
293   ierr = PetscMalloc(cn*(sizeof(MatScalar)+2*sizeof(PetscInt)),&apa);CHKERRQ(ierr);
294   ierr = PetscMemzero(apa,cn*(sizeof(MatScalar)+2*sizeof(PetscInt)));CHKERRQ(ierr);
295 
296   apj      = (PetscInt *)(apa + cn);
297   apjdense = apj + cn;
298 
299   /* Clear old values in C */
300   ierr = PetscMemzero(ca,ci[cm]*sizeof(MatScalar));CHKERRQ(ierr);
301 
302   for (i=0;i<am;i++) {
303     /* Form sparse row of A*P */
304     anzi  = ai[i+1] - ai[i];
305     apnzj = 0;
306     for (j=0;j<anzi;j++) {
307       prow = *aj++;
308       pnzj = pi[prow+1] - pi[prow];
309       pjj  = pj + pi[prow];
310       paj  = pa + pi[prow];
311       for (k=0;k<pnzj;k++) {
312         if (!apjdense[pjj[k]]) {
313           apjdense[pjj[k]] = -1;
314           apj[apnzj++]     = pjj[k];
315         }
316         apa[pjj[k]] += (*aa)*paj[k];
317       }
318       flops += 2*pnzj;
319       aa++;
320     }
321 
322     /* Sort the j index array for quick sparse axpy. */
323     ierr = PetscSortInt(apnzj,apj);CHKERRQ(ierr);
324 
325     /* Compute P^T*A*P using outer product (P^T)[:,j]*(A*P)[j,:]. */
326     pnzi = pi[i+1] - pi[i];
327     for (j=0;j<pnzi;j++) {
328       nextap = 0;
329       crow   = *pJ++;
330       cjj    = cj + ci[crow];
331       caj    = ca + ci[crow];
332       /* Perform sparse axpy operation.  Note cjj includes apj. */
333       for (k=0;nextap<apnzj;k++) {
334         if (cjj[k]==apj[nextap]) {
335           caj[k] += (*pA)*apa[apj[nextap++]];
336         }
337       }
338       flops += 2*apnzj;
339       pA++;
340     }
341 
342     /* Zero the current row info for A*P */
343     for (j=0;j<apnzj;j++) {
344       apa[apj[j]]      = 0.;
345       apjdense[apj[j]] = 0;
346     }
347   }
348 
349   /* Assemble the final matrix and clean up */
350   ierr = MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
351   ierr = MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
352   ierr = PetscFree(apa);CHKERRQ(ierr);
353   ierr = PetscLogFlops(flops);CHKERRQ(ierr);
354 
355   PetscFunctionReturn(0);
356 }
357