xref: /petsc/src/mat/impls/aij/seq/aijfact.c (revision 289bc588618de054f36015f5c3d330cf718be7c1)
1 
2 
3 #include "aij.h"
4 
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, j, n = aij->m, *ai = aij->i, *aj = aij->j;
14   int     prow, *ainew,*ajnew, jmax,*fill, *ajtmp, nz , *ii;
15   int     *idnew, idx, pivot_row,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, fact); CHKERR(ierr);
97   aijnew = (Matiaij *) (*fact)->data;
98   FREE(aijnew->imax);
99   aijnew->singlemalloc = 0;
100   len = ainew[n] - 1;
101   aijnew->a         = (Scalar *) MALLOC( len ); CHKPTR(aijnew->a);
102   aijnew->j         = ajnew;
103   aijnew->i         = ainew;
104   aij->diag         = idnew;
105   (*fact)->row      = isrow;
106   (*fact)->col      = iscol;
107   (*fact)->factor   = FACTOR_LU;
108   return 0;
109 }
110 
111 int MatiAIJLUFactorNumeric(Mat mat,Mat fact)
112 {
113   Matiaij *aij = (Matiaij *) mat->data, *aijnew = (Matiaij *)fact->data;
114   IS      iscol = fact->col, isrow = fact->row, isicol;
115   int     *r,*ic, ierr, i, j, n = aij->m, *ai = aijnew->i, *aj = aijnew->j;
116   int     prow, *ainew,*ajnew, jmax,*fill, *ajtmpold, *ajtmp, nz , *ii;
117   int     *idnew, idx, pivot_row,row,m,fm, nnz, nzi,len;
118   Scalar  *rtmp,*vnew,*v;
119 
120   if (ierr = ISInvertPermutation(iscol,&isicol)) SETERR(ierr,0);
121   ISGetIndices(isrow,&r);  ISGetIndices(isicol,&ic);
122   rtmp = (Scalar *) MALLOC( (n+1)*sizeof(Scalar) ); CHKPTR(rtmp);
123 
124   for ( i=0; i<n; i++ ) {
125     nz = ai[i+1] - ai[i];
126     ajtmp = aj + ai[i] - 1;
127     vnew  = aij->a + ai[i] - 1;
128     for  ( j=0; j<nz; j++ ) rtmp[ajtmp[j]-1] = 0.0;
129 
130     /* load in initial (unfactored row) */
131     nz = aij->i[i+1] - aij->i[i];
132     ajtmpold = aij->j + aij->i[i] - 1;
133     v  = aij->a + aij->i[i] - 1;
134     for ( j=0; j<nz; j++ ) rtmp[ic[ajtmpold[j]-1]] =  v[i];
135 
136     row = *ajtmp++:
137     while (row < i) {
138       pc = rm
139     }
140   }
141   ISDestroy(isicol);
142 
143   return 0;
144 }
145