Actual source code: baijsolvtrannat1.c
1: #include <../src/mat/impls/baij/seq/baij.h>
3: PetscErrorCode MatSolveTranspose_SeqBAIJ_1_NaturalOrdering(Mat A,Vec bb,Vec xx)
4: {
5: Mat_SeqBAIJ *a = (Mat_SeqBAIJ*)A->data;
6: const PetscInt *adiag = a->diag,*ai = a->i,*aj = a->j,*vi;
7: PetscInt i,n = a->mbs,j;
8: PetscInt nz;
9: PetscScalar *x,*tmp,s1;
10: const MatScalar *aa = a->a,*v;
11: const PetscScalar *b;
13: VecGetArrayRead(bb,&b);
14: VecGetArray(xx,&x);
15: tmp = a->solve_work;
17: /* copy the b into temp work space according to permutation */
18: for (i=0; i<n; i++) tmp[i] = b[i];
20: /* forward solve the U^T */
21: for (i=0; i<n; i++) {
22: v = aa + adiag[i+1] + 1;
23: vi = aj + adiag[i+1] + 1;
24: nz = adiag[i] - adiag[i+1] - 1;
25: s1 = tmp[i];
26: s1 *= v[nz]; /* multiply by inverse of diagonal entry */
27: for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j];
28: tmp[i] = s1;
29: }
31: /* backward solve the L^T */
32: for (i=n-1; i>=0; i--) {
33: v = aa + ai[i];
34: vi = aj + ai[i];
35: nz = ai[i+1] - ai[i];
36: s1 = tmp[i];
37: for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j];
38: }
40: /* copy tmp into x according to permutation */
41: for (i=0; i<n; i++) x[i] = tmp[i];
43: VecRestoreArrayRead(bb,&b);
44: VecRestoreArray(xx,&x);
46: PetscLogFlops(2.0*a->nz-A->cmap->n);
47: return 0;
48: }
50: PetscErrorCode MatSolveTranspose_SeqBAIJ_1_NaturalOrdering_inplace(Mat A,Vec bb,Vec xx)
51: {
52: Mat_SeqBAIJ *a=(Mat_SeqBAIJ*)A->data;
53: PetscInt i,nz;
54: const PetscInt *diag = a->diag,n=a->mbs,*vi,*ai=a->i,*aj=a->j;
55: const MatScalar *aa =a->a,*v;
56: PetscScalar s1,*x;
58: VecCopy(bb,xx);
59: VecGetArray(xx,&x);
61: /* forward solve the U^T */
62: for (i=0; i<n; i++) {
64: v = aa + diag[i];
65: /* multiply by the inverse of the block diagonal */
66: s1 = (*v++)*x[i];
67: vi = aj + diag[i] + 1;
68: nz = ai[i+1] - diag[i] - 1;
69: while (nz--) {
70: x[*vi++] -= (*v++)*s1;
71: }
72: x[i] = s1;
73: }
74: /* backward solve the L^T */
75: for (i=n-1; i>=0; i--) {
76: v = aa + diag[i] - 1;
77: vi = aj + diag[i] - 1;
78: nz = diag[i] - ai[i];
79: s1 = x[i];
80: while (nz--) {
81: x[*vi--] -= (*v--)*s1;
82: }
83: }
84: VecRestoreArray(xx,&x);
85: PetscLogFlops(2.0*(a->nz) - A->cmap->n);
86: return 0;
87: }