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: PetscFunctionBegin;
14: PetscCall(VecGetArrayRead(bb, &b));
15: PetscCall(VecGetArray(xx, &x));
16: tmp = a->solve_work;
18: /* copy the b into temp work space according to permutation */
19: for (i = 0; i < n; i++) tmp[i] = b[i];
21: /* forward solve the U^T */
22: for (i = 0; i < n; i++) {
23: v = aa + adiag[i + 1] + 1;
24: vi = aj + adiag[i + 1] + 1;
25: nz = adiag[i] - adiag[i + 1] - 1;
26: s1 = tmp[i];
27: s1 *= v[nz]; /* multiply by inverse of diagonal entry */
28: for (j = 0; j < nz; j++) tmp[vi[j]] -= s1 * v[j];
29: tmp[i] = s1;
30: }
32: /* backward solve the L^T */
33: for (i = n - 1; i >= 0; i--) {
34: v = aa + ai[i];
35: vi = aj + ai[i];
36: nz = ai[i + 1] - ai[i];
37: s1 = tmp[i];
38: for (j = 0; j < nz; j++) tmp[vi[j]] -= s1 * v[j];
39: }
41: /* copy tmp into x according to permutation */
42: for (i = 0; i < n; i++) x[i] = tmp[i];
44: PetscCall(VecRestoreArrayRead(bb, &b));
45: PetscCall(VecRestoreArray(xx, &x));
47: PetscCall(PetscLogFlops(2.0 * a->nz - A->cmap->n));
48: PetscFunctionReturn(PETSC_SUCCESS);
49: }
51: PetscErrorCode MatSolveTranspose_SeqBAIJ_1_NaturalOrdering_inplace(Mat A, Vec bb, Vec xx)
52: {
53: Mat_SeqBAIJ *a = (Mat_SeqBAIJ *)A->data;
54: PetscInt i, nz;
55: const PetscInt *diag = a->diag, n = a->mbs, *vi, *ai = a->i, *aj = a->j;
56: const MatScalar *aa = a->a, *v;
57: PetscScalar s1, *x;
59: PetscFunctionBegin;
60: PetscCall(VecCopy(bb, xx));
61: PetscCall(VecGetArray(xx, &x));
63: /* forward solve the U^T */
64: for (i = 0; i < n; i++) {
65: v = aa + diag[i];
66: /* multiply by the inverse of the block diagonal */
67: s1 = (*v++) * x[i];
68: vi = aj + diag[i] + 1;
69: nz = ai[i + 1] - diag[i] - 1;
70: while (nz--) x[*vi++] -= (*v++) * s1;
71: x[i] = s1;
72: }
73: /* backward solve the L^T */
74: for (i = n - 1; i >= 0; i--) {
75: v = aa + diag[i] - 1;
76: vi = aj + diag[i] - 1;
77: nz = diag[i] - ai[i];
78: s1 = x[i];
79: while (nz--) x[*vi--] -= (*v--) * s1;
80: }
81: PetscCall(VecRestoreArray(xx, &x));
82: PetscCall(PetscLogFlops(2.0 * (a->nz) - A->cmap->n));
83: PetscFunctionReturn(PETSC_SUCCESS);
84: }