1 #include <../src/mat/impls/baij/seq/baij.h> 2 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 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