1 #include <../src/mat/impls/baij/seq/baij.h> 2 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; 13 14 PetscFunctionBegin; 15 ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr); 16 ierr = VecGetArray(xx,&x);CHKERRQ(ierr); 17 tmp = a->solve_work; 18 19 20 /* copy the b into temp work space according to permutation */ 21 for (i=0; i<n; i++) tmp[i] = b[i]; 22 23 /* forward solve the U^T */ 24 for (i=0; i<n; i++) { 25 v = aa + adiag[i+1] + 1; 26 vi = aj + adiag[i+1] + 1; 27 nz = adiag[i] - adiag[i+1] - 1; 28 s1 = tmp[i]; 29 s1 *= v[nz]; /* multiply by inverse of diagonal entry */ 30 for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j]; 31 tmp[i] = s1; 32 } 33 34 /* backward solve the L^T */ 35 for (i=n-1; i>=0; i--) { 36 v = aa + ai[i]; 37 vi = aj + ai[i]; 38 nz = ai[i+1] - ai[i]; 39 s1 = tmp[i]; 40 for (j=0; j<nz; j++) tmp[vi[j]] -= s1*v[j]; 41 } 42 43 /* copy tmp into x according to permutation */ 44 for (i=0; i<n; i++) x[i] = tmp[i]; 45 46 ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr); 47 ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr); 48 49 ierr = PetscLogFlops(2.0*a->nz-A->cmap->n);CHKERRQ(ierr); 50 PetscFunctionReturn(0); 51 } 52 53 PetscErrorCode MatSolveTranspose_SeqBAIJ_1_NaturalOrdering_inplace(Mat A,Vec bb,Vec xx) 54 { 55 Mat_SeqBAIJ *a=(Mat_SeqBAIJ*)A->data; 56 PetscErrorCode ierr; 57 PetscInt i,nz; 58 const PetscInt *diag = a->diag,n=a->mbs,*vi,*ai=a->i,*aj=a->j; 59 const MatScalar *aa =a->a,*v; 60 PetscScalar s1,*x; 61 62 PetscFunctionBegin; 63 ierr = VecCopy(bb,xx);CHKERRQ(ierr); 64 ierr = VecGetArray(xx,&x);CHKERRQ(ierr); 65 66 /* forward solve the U^T */ 67 for (i=0; i<n; i++) { 68 69 v = aa + diag[i]; 70 /* multiply by the inverse of the block diagonal */ 71 s1 = (*v++)*x[i]; 72 vi = aj + diag[i] + 1; 73 nz = ai[i+1] - diag[i] - 1; 74 while (nz--) { 75 x[*vi++] -= (*v++)*s1; 76 } 77 x[i] = s1; 78 } 79 /* backward solve the L^T */ 80 for (i=n-1; i>=0; i--) { 81 v = aa + diag[i] - 1; 82 vi = aj + diag[i] - 1; 83 nz = diag[i] - ai[i]; 84 s1 = x[i]; 85 while (nz--) { 86 x[*vi--] -= (*v--)*s1; 87 } 88 } 89 ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr); 90 ierr = PetscLogFlops(2.0*(a->nz) - A->cmap->n);CHKERRQ(ierr); 91 PetscFunctionReturn(0); 92 } 93 94