Actual source code: baijsolvtran1.c

  1: #include <../src/mat/impls/baij/seq/baij.h>
  2: #include <petsc/private/kernels/blockinvert.h>

  4: PetscErrorCode MatSolveTranspose_SeqBAIJ_1(Mat A, Vec bb, Vec xx)
  5: {
  6:   Mat_SeqBAIJ       *a     = (Mat_SeqBAIJ *)A->data;
  7:   IS                 iscol = a->col, isrow = a->row;
  8:   const PetscInt    *rout, *cout, *r, *c, *adiag = a->diag, *ai = a->i, *aj = a->j, *vi;
  9:   PetscInt           i, n = a->mbs, j;
 10:   PetscInt           nz;
 11:   PetscScalar       *x, *tmp, s1;
 12:   const MatScalar   *aa = a->a, *v;
 13:   const PetscScalar *b;

 15:   VecGetArrayRead(bb, &b);
 16:   VecGetArray(xx, &x);
 17:   tmp = a->solve_work;

 19:   ISGetIndices(isrow, &rout);
 20:   r = rout;
 21:   ISGetIndices(iscol, &cout);
 22:   c = cout;

 24:   /* copy the b into temp work space according to permutation */
 25:   for (i = 0; i < n; i++) tmp[i] = b[c[i]];

 27:   /* forward solve the U^T */
 28:   for (i = 0; i < n; i++) {
 29:     v  = aa + adiag[i + 1] + 1;
 30:     vi = aj + adiag[i + 1] + 1;
 31:     nz = adiag[i] - adiag[i + 1] - 1;
 32:     s1 = tmp[i];
 33:     s1 *= v[nz]; /* multiply by inverse of diagonal entry */
 34:     for (j = 0; j < nz; j++) tmp[vi[j]] -= s1 * v[j];
 35:     tmp[i] = s1;
 36:   }

 38:   /* backward solve the L^T */
 39:   for (i = n - 1; i >= 0; i--) {
 40:     v  = aa + ai[i];
 41:     vi = aj + ai[i];
 42:     nz = ai[i + 1] - ai[i];
 43:     s1 = tmp[i];
 44:     for (j = 0; j < nz; j++) tmp[vi[j]] -= s1 * v[j];
 45:   }

 47:   /* copy tmp into x according to permutation */
 48:   for (i = 0; i < n; i++) x[r[i]] = tmp[i];

 50:   ISRestoreIndices(isrow, &rout);
 51:   ISRestoreIndices(iscol, &cout);
 52:   VecRestoreArrayRead(bb, &b);
 53:   VecRestoreArray(xx, &x);

 55:   PetscLogFlops(2.0 * a->nz - A->cmap->n);
 56:   return 0;
 57: }

 59: PetscErrorCode MatSolveTranspose_SeqBAIJ_1_inplace(Mat A, Vec bb, Vec xx)
 60: {
 61:   Mat_SeqBAIJ       *a     = (Mat_SeqBAIJ *)A->data;
 62:   IS                 iscol = a->col, isrow = a->row;
 63:   const PetscInt    *r, *c, *rout, *cout;
 64:   const PetscInt    *diag = a->diag, n = a->mbs, *vi, *ai = a->i, *aj = a->j;
 65:   PetscInt           i, nz;
 66:   const MatScalar   *aa = a->a, *v;
 67:   PetscScalar        s1, *x, *t;
 68:   const PetscScalar *b;

 70:   VecGetArrayRead(bb, &b);
 71:   VecGetArray(xx, &x);
 72:   t = a->solve_work;

 74:   ISGetIndices(isrow, &rout);
 75:   r = rout;
 76:   ISGetIndices(iscol, &cout);
 77:   c = cout;

 79:   /* copy the b into temp work space according to permutation */
 80:   for (i = 0; i < n; i++) t[i] = b[c[i]];

 82:   /* forward solve the U^T */
 83:   for (i = 0; i < n; i++) {
 84:     v = aa + diag[i];
 85:     /* multiply by the inverse of the block diagonal */
 86:     s1 = (*v++) * t[i];
 87:     vi = aj + diag[i] + 1;
 88:     nz = ai[i + 1] - diag[i] - 1;
 89:     while (nz--) t[*vi++] -= (*v++) * s1;
 90:     t[i] = s1;
 91:   }
 92:   /* backward solve the L^T */
 93:   for (i = n - 1; i >= 0; i--) {
 94:     v  = aa + diag[i] - 1;
 95:     vi = aj + diag[i] - 1;
 96:     nz = diag[i] - ai[i];
 97:     s1 = t[i];
 98:     while (nz--) t[*vi--] -= (*v--) * s1;
 99:   }

101:   /* copy t into x according to permutation */
102:   for (i = 0; i < n; i++) x[r[i]] = t[i];

104:   ISRestoreIndices(isrow, &rout);
105:   ISRestoreIndices(iscol, &cout);
106:   VecRestoreArrayRead(bb, &b);
107:   VecRestoreArray(xx, &x);
108:   PetscLogFlops(2.0 * (a->nz) - A->cmap->n);
109:   return 0;
110: }