Actual source code: baijsolvtrannat1.c
petsc-3.14.6 2021-03-30
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: PetscErrorCode ierr;
7: const PetscInt *adiag = a->diag,*ai = a->i,*aj = a->j,*vi;
8: PetscInt i,n = a->mbs,j;
9: PetscInt nz;
10: PetscScalar *x,*tmp,s1;
11: const MatScalar *aa = a->a,*v;
12: const PetscScalar *b;
15: VecGetArrayRead(bb,&b);
16: VecGetArray(xx,&x);
17: tmp = a->solve_work;
20: /* copy the b into temp work space according to permutation */
21: for (i=0; i<n; i++) tmp[i] = b[i];
23: /* forward solve the U^T */
24: for (i=0; i<n; i++) {
25: v = aa + adiag[i+1] + 1;
26: vi = aj + adiag[i+1] + 1;
27: nz = adiag[i] - adiag[i+1] - 1;
28: s1 = tmp[i];
29: s1 *= v[nz]; /* multiply by inverse of diagonal entry */
30: for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j];
31: tmp[i] = s1;
32: }
34: /* backward solve the L^T */
35: for (i=n-1; i>=0; i--) {
36: v = aa + ai[i];
37: vi = aj + ai[i];
38: nz = ai[i+1] - ai[i];
39: s1 = tmp[i];
40: for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j];
41: }
43: /* copy tmp into x according to permutation */
44: for (i=0; i<n; i++) x[i] = tmp[i];
46: VecRestoreArrayRead(bb,&b);
47: VecRestoreArray(xx,&x);
49: PetscLogFlops(2.0*a->nz-A->cmap->n);
50: return(0);
51: }
53: PetscErrorCode MatSolveTranspose_SeqBAIJ_1_NaturalOrdering_inplace(Mat A,Vec bb,Vec xx)
54: {
55: Mat_SeqBAIJ *a=(Mat_SeqBAIJ*)A->data;
56: PetscErrorCode ierr;
57: PetscInt i,nz;
58: const PetscInt *diag = a->diag,n=a->mbs,*vi,*ai=a->i,*aj=a->j;
59: const MatScalar *aa =a->a,*v;
60: PetscScalar s1,*x;
63: VecCopy(bb,xx);
64: VecGetArray(xx,&x);
66: /* forward solve the U^T */
67: for (i=0; i<n; i++) {
69: v = aa + diag[i];
70: /* multiply by the inverse of the block diagonal */
71: s1 = (*v++)*x[i];
72: vi = aj + diag[i] + 1;
73: nz = ai[i+1] - diag[i] - 1;
74: while (nz--) {
75: x[*vi++] -= (*v++)*s1;
76: }
77: x[i] = s1;
78: }
79: /* backward solve the L^T */
80: for (i=n-1; i>=0; i--) {
81: v = aa + diag[i] - 1;
82: vi = aj + diag[i] - 1;
83: nz = diag[i] - ai[i];
84: s1 = x[i];
85: while (nz--) {
86: x[*vi--] -= (*v--)*s1;
87: }
88: }
89: VecRestoreArray(xx,&x);
90: PetscLogFlops(2.0*(a->nz) - A->cmap->n);
91: return(0);
92: }