Actual source code: baijsolvtrannat1.c

  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;

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

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

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

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

 45:   VecRestoreArrayRead(bb,&b);
 46:   VecRestoreArray(xx,&x);

 48:   PetscLogFlops(2.0*a->nz-A->cmap->n);
 49:   return(0);
 50: }

 52: PetscErrorCode MatSolveTranspose_SeqBAIJ_1_NaturalOrdering_inplace(Mat A,Vec bb,Vec xx)
 53: {
 54:   Mat_SeqBAIJ     *a=(Mat_SeqBAIJ*)A->data;
 55:   PetscErrorCode  ierr;
 56:   PetscInt        i,nz;
 57:   const PetscInt  *diag = a->diag,n=a->mbs,*vi,*ai=a->i,*aj=a->j;
 58:   const MatScalar *aa   =a->a,*v;
 59:   PetscScalar     s1,*x;

 62:   VecCopy(bb,xx);
 63:   VecGetArray(xx,&x);

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

 68:     v = aa + diag[i];
 69:     /* multiply by the inverse of the block diagonal */
 70:     s1 = (*v++)*x[i];
 71:     vi = aj + diag[i] + 1;
 72:     nz = ai[i+1] - diag[i] - 1;
 73:     while (nz--) {
 74:       x[*vi++] -= (*v++)*s1;
 75:     }
 76:     x[i] = s1;
 77:   }
 78:   /* backward solve the L^T */
 79:   for (i=n-1; i>=0; i--) {
 80:     v  = aa + diag[i] - 1;
 81:     vi = aj + diag[i] - 1;
 82:     nz = diag[i] - ai[i];
 83:     s1 = x[i];
 84:     while (nz--) {
 85:       x[*vi--] -=  (*v--)*s1;
 86:     }
 87:   }
 88:   VecRestoreArray(xx,&x);
 89:   PetscLogFlops(2.0*(a->nz) - A->cmap->n);
 90:   return(0);
 91: }