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:   const PetscInt    *adiag = a->diag,*ai = a->i,*aj = a->j,*vi;
  7:   PetscInt          i,n = a->mbs,j;
  8:   PetscInt          nz;
  9:   PetscScalar       *x,*tmp,s1;
 10:   const MatScalar   *aa = a->a,*v;
 11:   const PetscScalar *b;

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

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

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

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

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

 43:   VecRestoreArrayRead(bb,&b);
 44:   VecRestoreArray(xx,&x);

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

 50: PetscErrorCode MatSolveTranspose_SeqBAIJ_1_NaturalOrdering_inplace(Mat A,Vec bb,Vec xx)
 51: {
 52:   Mat_SeqBAIJ     *a=(Mat_SeqBAIJ*)A->data;
 53:   PetscInt        i,nz;
 54:   const PetscInt  *diag = a->diag,n=a->mbs,*vi,*ai=a->i,*aj=a->j;
 55:   const MatScalar *aa   =a->a,*v;
 56:   PetscScalar     s1,*x;

 58:   VecCopy(bb,xx);
 59:   VecGetArray(xx,&x);

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

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