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++) {
63: v = aa + diag[i];
64: /* multiply by the inverse of the block diagonal */
65: s1 = (*v++) * x[i];
66: vi = aj + diag[i] + 1;
67: nz = ai[i + 1] - diag[i] - 1;
68: while (nz--) x[*vi++] -= (*v++) * s1;
69: x[i] = s1;
70: }
71: /* backward solve the L^T */
72: for (i = n - 1; i >= 0; i--) {
73: v = aa + diag[i] - 1;
74: vi = aj + diag[i] - 1;
75: nz = diag[i] - ai[i];
76: s1 = x[i];
77: while (nz--) x[*vi--] -= (*v--) * s1;
78: }
79: VecRestoreArray(xx, &x);
80: PetscLogFlops(2.0 * (a->nz) - A->cmap->n);
81: return 0;
82: }