xref: /petsc/src/mat/impls/aij/seq/aijfact.c (revision 6abc6512c105a871402f018420c4c4316bc1e68d)
1 
2 
3 #include "aij.h"
4 #include "inline/spops.h"
5 /*
6     Factorization code for AIJ format.
7 */
8 
9 int MatiAIJLUFactorSymbolic(Mat mat,IS isrow,IS iscol,Mat *fact)
10 {
11   Matiaij *aij = (Matiaij *) mat->data, *aijnew;
12   IS      isicol;
13   int     *r,*ic, ierr, i, n = aij->m, *ai = aij->i, *aj = aij->j;
14   int     *ainew,*ajnew, jmax,*fill, *ajtmp, nz;
15   int     *idnew, idx, row,m,fm, nnz, nzi,len;
16 
17   if (n != aij->n) SETERR(1,"Mat must be square");
18   if (!isrow) {SETERR(1,"Must have row permutation");}
19   if (!iscol) {SETERR(1,"Must have column permutation");}
20 
21   if ((ierr = ISInvertPermutation(iscol,&isicol))) SETERR(ierr,0);
22   ISGetIndices(isrow,&r); ISGetIndices(isicol,&ic);
23 
24   /* get new row pointers */
25   ainew = (int *) MALLOC( (n+1)*sizeof(int) ); CHKPTR(ainew);
26   ainew[0] = 1;
27   /* don't know how many column pointers are needed so estimate */
28   jmax = 2*ai[n];
29   ajnew = (int *) MALLOC( (jmax)*sizeof(int) ); CHKPTR(ajnew);
30   /* fill is a linked list of nonzeros in active row */
31   fill = (int *) MALLOC( (n+1)*sizeof(int)); CHKPTR(fill);
32   /* idnew is location of diagonal in factor */
33   idnew = (int *) MALLOC( (n+1)*sizeof(int)); CHKPTR(idnew);
34   idnew[0] = 1;
35 
36   for ( i=0; i<n; i++ ) {
37     /* first copy previous fill into linked list */
38     nnz = nz    = ai[r[i]+1] - ai[r[i]];
39     ajtmp = aj + ai[r[i]] - 1;
40     fill[n] = n;
41     while (nz--) {
42       fm = n;
43       idx = ic[*ajtmp++ - 1];
44       do {
45         m = fm;
46         fm = fill[m];
47       } while (fm < idx);
48       fill[m] = idx;
49       fill[idx] = fm;
50     }
51     row = fill[n];
52     while ( row < i ) {
53       ajtmp = ajnew + idnew[row] - 1;
54       nz = ainew[row+1] - idnew[row];
55       fm = row;
56       while (nz--) {
57         fm = n;
58         idx = *ajtmp++ - 1;
59         do {
60           m = fm;
61           fm = fill[m];
62         } while (fm < idx);
63         if (fm != idx) {
64           fill[m] = idx;
65           fill[idx] = fm;
66           fm = idx;
67           nnz++;
68         }
69       }
70       row = fill[row];
71     }
72     /* copy new filled row into permanent storage */
73     ainew[i+1] = ainew[i] + nnz;
74     if (ainew[i+1] > jmax+1) {
75       /* allocate a longer ajnew */
76       jmax += nnz*(n-i);
77       ajtmp = (int *) MALLOC( jmax*sizeof(int) );CHKPTR(ajtmp);
78       MEMCPY(ajtmp,ajnew,(ainew[i]-1)*sizeof(int));
79       FREE(ajnew);
80       ajnew = ajtmp;
81     }
82     ajtmp = ajnew + ainew[i] - 1;
83     fm = fill[n];
84     nzi = 0;
85     while (nnz--) {
86       if (fm < i) nzi++;
87       *ajtmp++ = fm + 1;
88       fm = fill[fm];
89     }
90     idnew[i] = ainew[i] + nzi;
91   }
92 
93   ISDestroy(isicol); FREE(fill);
94 
95   /* put together the new matrix */
96   ierr = MatCreateSequentialAIJ(n, n, 0, 0, fact); CHKERR(ierr);
97   aijnew = (Matiaij *) (*fact)->data;
98   FREE(aijnew->imax);
99   aijnew->singlemalloc = 0;
100   len = (ainew[n] - 1)*sizeof(Scalar);
101   /* the next line frees the default space generated by the Create() */
102   FREE(aijnew->a); FREE(aijnew->ilen);
103   aijnew->a         = (Scalar *) MALLOC( len ); CHKPTR(aijnew->a);
104   aijnew->j         = ajnew;
105   aijnew->i         = ainew;
106   aijnew->diag      = idnew;
107   aijnew->ilen      = 0;
108   aijnew->imax      = 0;
109   (*fact)->row      = isrow;
110   (*fact)->col      = iscol;
111   (*fact)->factor   = FACTOR_LU;
112   return 0;
113 }
114 
115 int MatiAIJLUFactorNumeric(Mat mat,Mat *infact)
116 {
117   Mat     fact = *infact;
118   Matiaij *aij = (Matiaij *) mat->data, *aijnew = (Matiaij *)fact->data;
119   IS      iscol = fact->col, isrow = fact->row, isicol;
120   int     *r,*ic, ierr, i, j, n = aij->m, *ai = aijnew->i, *aj = aijnew->j;
121   int     *ajtmpold, *ajtmp, nz, row,*pj;
122   Scalar  *rtmp,*v, *pv, *pc, multiplier;
123 
124   if ((ierr = ISInvertPermutation(iscol,&isicol))) SETERR(ierr,0);
125   ierr = ISGetIndices(isrow,&r); CHKERR(ierr);
126   ierr = ISGetIndices(isicol,&ic); CHKERR(ierr);
127   rtmp = (Scalar *) MALLOC( (n+1)*sizeof(Scalar) ); CHKPTR(rtmp);
128 
129   for ( i=0; i<n; i++ ) {
130     nz = ai[i+1] - ai[i];
131     ajtmp = aj + ai[i] - 1;
132     for  ( j=0; j<nz; j++ ) rtmp[ajtmp[j]-1] = 0.0;
133 
134     /* load in initial (unfactored row) */
135     nz = aij->i[r[i]+1] - aij->i[r[i]];
136     ajtmpold = aij->j + aij->i[r[i]] - 1;
137     v  = aij->a + aij->i[r[i]] - 1;
138     for ( j=0; j<nz; j++ ) rtmp[ic[ajtmpold[j]-1]] =  v[j];
139 
140     row = *ajtmp++ - 1;
141     while (row < i) {
142       pc = rtmp + row;
143       if (*pc != 0.0) {
144         nz = aijnew->diag[row] - ai[row];
145         pv = aijnew->a + aijnew->diag[row] - 1;
146         pj = aijnew->j + aijnew->diag[row];
147         multiplier = *pc * *pv++;
148         *pc = multiplier;
149         nz = ai[row+1] - ai[row] - 1 - nz;
150         while (nz-->0) rtmp[*pj++ - 1] -= multiplier* *pv++;
151       }
152       row = *ajtmp++ - 1;
153     }
154     /* finished row so stick it into aijnew->a */
155     pv = aijnew->a + ai[i] - 1;
156     pj = aijnew->j + ai[i] - 1;
157     nz = ai[i+1] - ai[i];
158     rtmp[i] = 1.0/rtmp[i];
159     for ( j=0; j<nz; j++ ) {pv[j] = rtmp[pj[j]-1];}
160   }
161   FREE(rtmp);
162   ierr = ISRestoreIndices(isicol,&ic); CHKERR(ierr);
163   ierr = ISRestoreIndices(isrow,&r); CHKERR(ierr);
164   ierr = ISDestroy(isicol); CHKERR(ierr);
165   fact->factor = FACTOR_LU;
166 
167   return 0;
168 }
169 int MatiAIJLUFactor(Mat matin,IS row,IS col)
170 {
171   Matiaij *mat = (Matiaij *) matin->data;
172   int     ierr;
173   Mat     fact;
174   ierr = MatiAIJLUFactorSymbolic(matin,row,col,&fact); CHKERR(ierr);
175   ierr = MatiAIJLUFactorNumeric(matin,&fact); CHKERR(ierr);
176 
177   /* free all the data structures from mat */
178   FREE(mat->a);
179   if (!mat->singlemalloc) {FREE(mat->i); FREE(mat->j);}
180   if (mat->diag) FREE(mat->diag);
181   if (mat->ilen) FREE(mat->ilen);
182   if (mat->imax) FREE(mat->imax);
183   if (matin->row && matin->col && matin->row != matin->col) {
184     ISDestroy(matin->row);
185   }
186   if (matin->col) ISDestroy(matin->col);
187   FREE(mat);
188 
189   MEMCPY(matin,fact,sizeof(struct _Mat));
190   FREE(fact);
191   return 0;
192 }
193 
194 int MatiAIJSolve(Mat mat,Vec bb, Vec xx)
195 {
196   Matiaij *aij = (Matiaij *) mat->data;
197   IS      iscol = mat->col, isrow = mat->row;
198   int     *r,*c, ierr, i,  n = aij->m, *vi, *ai = aij->i, *aj = aij->j;
199   int     nz;
200   Scalar  *x,*b,*tmp, *aa = aij->a, sum, *v;
201 
202   if ((ierr = VecGetArray(bb,&b))) SETERR(ierr,0);
203   if ((ierr = VecGetArray(xx,&x))) SETERR(ierr,0);
204   tmp = (Scalar *) MALLOC(n*sizeof(Scalar)); CHKPTR(tmp);
205 
206   if ((ierr = ISGetIndices(isrow,&r))) SETERR(ierr,0);
207   if ((ierr = ISGetIndices(iscol,&c))) SETERR(ierr,0); c = c + (n-1);
208 
209   /* forward solve the lower triangular */
210   tmp[0] = b[*r++];
211   for ( i=1; i<n; i++ ) {
212     v   = aa + ai[i] - 1;
213     vi  = aj + ai[i] - 1;
214     nz  = aij->diag[i] - ai[i];
215     sum = b[*r++];
216     while (nz--) sum -= *v++ * tmp[*vi++ - 1];
217     tmp[i] = sum;
218   }
219 
220   /* backward solve the upper triangular */
221   for ( i=n-1; i>=0; i-- ){
222     v   = aa + aij->diag[i];
223     vi  = aj + aij->diag[i];
224     nz  = ai[i+1] - aij->diag[i] - 1;
225     sum = tmp[i];
226     while (nz--) sum -= *v++ * tmp[*vi++ - 1];
227     x[*c--] = tmp[i] = sum*aa[aij->diag[i]-1];
228   }
229 
230   FREE(tmp);
231   return 0;
232 }
233 int MatiAIJSolveAdd(Mat mat,Vec bb, Vec yy, Vec xx)
234 {
235   Matiaij *aij = (Matiaij *) mat->data;
236   IS      iscol = mat->col, isrow = mat->row;
237   int     *r,*c, ierr, i,  n = aij->m, *vi, *ai = aij->i, *aj = aij->j;
238   int     nz;
239   Scalar  *x,*b,*tmp, *aa = aij->a, sum, *v;
240 
241   if (yy != xx) {ierr = VecCopy(yy,xx); CHKERR(ierr);}
242 
243   if ((ierr = VecGetArray(bb,&b))) SETERR(ierr,0);
244   if ((ierr = VecGetArray(xx,&x))) SETERR(ierr,0);
245   tmp = (Scalar *) MALLOC(n*sizeof(Scalar)); CHKPTR(tmp);
246 
247   if ((ierr = ISGetIndices(isrow,&r))) SETERR(ierr,0);
248   if ((ierr = ISGetIndices(iscol,&c))) SETERR(ierr,0); c = c + (n-1);
249 
250   /* forward solve the lower triangular */
251   tmp[0] = b[*r++];
252   for ( i=1; i<n; i++ ) {
253     v   = aa + ai[i] - 1;
254     vi  = aj + ai[i] - 1;
255     nz  = aij->diag[i] - ai[i];
256     sum = b[*r++];
257     while (nz--) sum -= *v++ * tmp[*vi++ - 1];
258     tmp[i] = sum;
259   }
260 
261   /* backward solve the upper triangular */
262   for ( i=n-1; i>=0; i-- ){
263     v   = aa + aij->diag[i];
264     vi  = aj + aij->diag[i];
265     nz  = ai[i+1] - aij->diag[i] - 1;
266     sum = tmp[i];
267     while (nz--) sum -= *v++ * tmp[*vi++ - 1];
268     tmp[i] = sum*aa[aij->diag[i]-1];
269     x[*c--] += tmp[i];
270   }
271 
272   FREE(tmp);
273   return 0;
274 }
275 /* -------------------------------------------------------------------*/
276 int MatiAIJSolveTrans(Mat mat,Vec bb, Vec xx)
277 {
278   Matiaij *aij = (Matiaij *) mat->data;
279   IS      iscol = mat->col, isrow = mat->row, invisrow,inviscol;
280   int     *r,*c, ierr, i, n = aij->m, *vi, *ai = aij->i, *aj = aij->j;
281   int     nz;
282   Scalar  *x,*b,*tmp, *aa = aij->a, *v;
283 
284   if ((ierr = VecGetArray(bb,&b))) SETERR(ierr,0);
285   if ((ierr = VecGetArray(xx,&x))) SETERR(ierr,0);
286   tmp = (Scalar *) MALLOC(n*sizeof(Scalar)); CHKPTR(tmp);
287 
288   /* invert the permutations */
289   ierr = ISInvertPermutation(isrow,&invisrow); CHKERR(ierr);
290   ierr = ISInvertPermutation(iscol,&inviscol); CHKERR(ierr);
291 
292 
293   if ((ierr = ISGetIndices(invisrow,&r))) SETERR(ierr,0);
294   if ((ierr = ISGetIndices(inviscol,&c))) SETERR(ierr,0);
295 
296   /* copy the b into temp work space according to permutation */
297   for ( i=0; i<n; i++ ) tmp[c[i]] = b[i];
298 
299   /* forward solve the U^T */
300   for ( i=0; i<n; i++ ) {
301     v   = aa + aij->diag[i] - 1;
302     vi  = aj + aij->diag[i];
303     nz  = ai[i+1] - aij->diag[i] - 1;
304     tmp[i] *= *v++;
305     while (nz--) {
306       tmp[*vi++ - 1] -= (*v++)*tmp[i];
307     }
308   }
309 
310   /* backward solve the L^T */
311   for ( i=n-1; i>=0; i-- ){
312     v   = aa + aij->diag[i] - 2;
313     vi  = aj + aij->diag[i] - 2;
314     nz  = aij->diag[i] - ai[i];
315     while (nz--) {
316       tmp[*vi-- - 1] -= (*v--)*tmp[i];
317     }
318   }
319 
320   /* copy tmp into x according to permutation */
321   for ( i=0; i<n; i++ ) x[r[i]] = tmp[i];
322 
323   ISDestroy(invisrow); ISDestroy(inviscol);
324 
325   FREE(tmp);
326   return 0;
327 }
328 
329 int MatiAIJSolveTransAdd(Mat mat,Vec bb, Vec zz,Vec xx)
330 {
331   Matiaij *aij = (Matiaij *) mat->data;
332   IS      iscol = mat->col, isrow = mat->row, invisrow,inviscol;
333   int     *r,*c, ierr, i, n = aij->m, *vi, *ai = aij->i, *aj = aij->j;
334   int     nz;
335   Scalar  *x,*b,*tmp, *aa = aij->a, *v;
336 
337   if (zz != xx) VecCopy(zz,xx);
338 
339   if ((ierr = VecGetArray(bb,&b))) SETERR(ierr,0);
340   if ((ierr = VecGetArray(xx,&x))) SETERR(ierr,0);
341   tmp = (Scalar *) MALLOC(n*sizeof(Scalar)); CHKPTR(tmp);
342 
343   /* invert the permutations */
344   ierr = ISInvertPermutation(isrow,&invisrow); CHKERR(ierr);
345   ierr = ISInvertPermutation(iscol,&inviscol); CHKERR(ierr);
346 
347 
348   if ((ierr = ISGetIndices(invisrow,&r))) SETERR(ierr,0);
349   if ((ierr = ISGetIndices(inviscol,&c))) SETERR(ierr,0);
350 
351   /* copy the b into temp work space according to permutation */
352   for ( i=0; i<n; i++ ) tmp[c[i]] = b[i];
353 
354   /* forward solve the U^T */
355   for ( i=0; i<n; i++ ) {
356     v   = aa + aij->diag[i] - 1;
357     vi  = aj + aij->diag[i];
358     nz  = ai[i+1] - aij->diag[i] - 1;
359     tmp[i] *= *v++;
360     while (nz--) {
361       tmp[*vi++ - 1] -= (*v++)*tmp[i];
362     }
363   }
364 
365   /* backward solve the L^T */
366   for ( i=n-1; i>=0; i-- ){
367     v   = aa + aij->diag[i] - 2;
368     vi  = aj + aij->diag[i] - 2;
369     nz  = aij->diag[i] - ai[i];
370     while (nz--) {
371       tmp[*vi-- - 1] -= (*v--)*tmp[i];
372     }
373   }
374 
375   /* copy tmp into x according to permutation */
376   for ( i=0; i<n; i++ ) x[r[i]] += tmp[i];
377 
378   ISDestroy(invisrow); ISDestroy(inviscol);
379 
380   FREE(tmp);
381   return 0;
382 
383 }
384