1 #include <../src/mat/impls/baij/seq/baij.h>
2
MatSolveTranspose_SeqBAIJ_2_NaturalOrdering_inplace(Mat A,Vec bb,Vec xx)3 PetscErrorCode MatSolveTranspose_SeqBAIJ_2_NaturalOrdering_inplace(Mat A, Vec bb, Vec xx)
4 {
5 Mat_SeqBAIJ *a = (Mat_SeqBAIJ *)A->data;
6 PetscInt i, nz, idx, idt, oidx;
7 const PetscInt *diag = a->diag, *vi, n = a->mbs, *ai = a->i, *aj = a->j;
8 const MatScalar *aa = a->a, *v;
9 PetscScalar s1, s2, x1, x2, *x;
10
11 PetscFunctionBegin;
12 PetscCall(VecCopy(bb, xx));
13 PetscCall(VecGetArray(xx, &x));
14
15 /* forward solve the U^T */
16 idx = 0;
17 for (i = 0; i < n; i++) {
18 v = aa + 4 * diag[i];
19 /* multiply by the inverse of the block diagonal */
20 x1 = x[idx];
21 x2 = x[1 + idx];
22 s1 = v[0] * x1 + v[1] * x2;
23 s2 = v[2] * x1 + v[3] * x2;
24 v += 4;
25
26 vi = aj + diag[i] + 1;
27 nz = ai[i + 1] - diag[i] - 1;
28 while (nz--) {
29 oidx = 2 * (*vi++);
30 x[oidx] -= v[0] * s1 + v[1] * s2;
31 x[oidx + 1] -= v[2] * s1 + v[3] * s2;
32 v += 4;
33 }
34 x[idx] = s1;
35 x[1 + idx] = s2;
36 idx += 2;
37 }
38 /* backward solve the L^T */
39 for (i = n - 1; i >= 0; i--) {
40 v = aa + 4 * diag[i] - 4;
41 vi = aj + diag[i] - 1;
42 nz = diag[i] - ai[i];
43 idt = 2 * i;
44 s1 = x[idt];
45 s2 = x[1 + idt];
46 while (nz--) {
47 idx = 2 * (*vi--);
48 x[idx] -= v[0] * s1 + v[1] * s2;
49 x[idx + 1] -= v[2] * s1 + v[3] * s2;
50 v -= 4;
51 }
52 }
53 PetscCall(VecRestoreArray(xx, &x));
54 PetscCall(PetscLogFlops(2.0 * 4.0 * (a->nz) - 2.0 * A->cmap->n));
55 PetscFunctionReturn(PETSC_SUCCESS);
56 }
57
MatSolveTranspose_SeqBAIJ_2_NaturalOrdering(Mat A,Vec bb,Vec xx)58 PetscErrorCode MatSolveTranspose_SeqBAIJ_2_NaturalOrdering(Mat A, Vec bb, Vec xx)
59 {
60 Mat_SeqBAIJ *a = (Mat_SeqBAIJ *)A->data;
61 const PetscInt n = a->mbs, *vi, *ai = a->i, *aj = a->j, *diag = a->diag;
62 PetscInt nz, idx, idt, j, i, oidx;
63 const PetscInt bs = A->rmap->bs, bs2 = a->bs2;
64 const MatScalar *aa = a->a, *v;
65 PetscScalar s1, s2, x1, x2, *x;
66
67 PetscFunctionBegin;
68 PetscCall(VecCopy(bb, xx));
69 PetscCall(VecGetArray(xx, &x));
70
71 /* forward solve the U^T */
72 idx = 0;
73 for (i = 0; i < n; i++) {
74 v = aa + bs2 * diag[i];
75 /* multiply by the inverse of the block diagonal */
76 x1 = x[idx];
77 x2 = x[1 + idx];
78 s1 = v[0] * x1 + v[1] * x2;
79 s2 = v[2] * x1 + v[3] * x2;
80 v -= bs2;
81
82 vi = aj + diag[i] - 1;
83 nz = diag[i] - diag[i + 1] - 1;
84 for (j = 0; j > -nz; j--) {
85 oidx = bs * vi[j];
86 x[oidx] -= v[0] * s1 + v[1] * s2;
87 x[oidx + 1] -= v[2] * s1 + v[3] * s2;
88 v -= bs2;
89 }
90 x[idx] = s1;
91 x[1 + idx] = s2;
92 idx += bs;
93 }
94 /* backward solve the L^T */
95 for (i = n - 1; i >= 0; i--) {
96 v = aa + bs2 * ai[i];
97 vi = aj + ai[i];
98 nz = ai[i + 1] - ai[i];
99 idt = bs * i;
100 s1 = x[idt];
101 s2 = x[1 + idt];
102 for (j = 0; j < nz; j++) {
103 idx = bs * vi[j];
104 x[idx] -= v[0] * s1 + v[1] * s2;
105 x[idx + 1] -= v[2] * s1 + v[3] * s2;
106 v += bs2;
107 }
108 }
109 PetscCall(VecRestoreArray(xx, &x));
110 PetscCall(PetscLogFlops(2.0 * bs2 * (a->nz) - bs * A->cmap->n));
111 PetscFunctionReturn(PETSC_SUCCESS);
112 }
113