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); r = rout;
 20:   ISGetIndices(iscol,&cout); c = cout;

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

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

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

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

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

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

 57: PetscErrorCode MatSolveTranspose_SeqBAIJ_1_inplace(Mat A,Vec bb,Vec xx)
 58: {
 59:   Mat_SeqBAIJ       *a   =(Mat_SeqBAIJ*)A->data;
 60:   IS                iscol=a->col,isrow=a->row;
 61:   const PetscInt    *r,*c,*rout,*cout;
 62:   const PetscInt    *diag=a->diag,n=a->mbs,*vi,*ai=a->i,*aj=a->j;
 63:   PetscInt          i,nz;
 64:   const MatScalar   *aa=a->a,*v;
 65:   PetscScalar       s1,*x,*t;
 66:   const PetscScalar *b;

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

 72:   ISGetIndices(isrow,&rout); r = rout;
 73:   ISGetIndices(iscol,&cout); c = cout;

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

 78:   /* forward solve the U^T */
 79:   for (i=0; i<n; i++) {

 81:     v = aa + diag[i];
 82:     /* multiply by the inverse of the block diagonal */
 83:     s1 = (*v++)*t[i];
 84:     vi = aj + diag[i] + 1;
 85:     nz = ai[i+1] - diag[i] - 1;
 86:     while (nz--) {
 87:       t[*vi++] -= (*v++)*s1;
 88:     }
 89:     t[i] = s1;
 90:   }
 91:   /* backward solve the L^T */
 92:   for (i=n-1; i>=0; i--) {
 93:     v  = aa + diag[i] - 1;
 94:     vi = aj + diag[i] - 1;
 95:     nz = diag[i] - ai[i];
 96:     s1 = t[i];
 97:     while (nz--) {
 98:       t[*vi--] -=  (*v--)*s1;
 99:     }
100:   }

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

105:   ISRestoreIndices(isrow,&rout);
106:   ISRestoreIndices(iscol,&cout);
107:   VecRestoreArrayRead(bb,&b);
108:   VecRestoreArray(xx,&x);
109:   PetscLogFlops(2.0*(a->nz) - A->cmap->n);
110:   return 0;
111: }