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 /* copy the b into temp work space according to permutation */ 20 for (i=0; i<n; i++) tmp[i] = b[i]; 21 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 } 32 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 } 41 42 /* copy tmp into x according to permutation */ 43 for (i=0; i<n; i++) x[i] = tmp[i]; 44 45 ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr); 46 ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr); 47 48 ierr = PetscLogFlops(2.0*a->nz-A->cmap->n);CHKERRQ(ierr); 49 PetscFunctionReturn(0); 50 } 51 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; 60 61 PetscFunctionBegin; 62 ierr = VecCopy(bb,xx);CHKERRQ(ierr); 63 ierr = VecGetArray(xx,&x);CHKERRQ(ierr); 64 65 /* forward solve the U^T */ 66 for (i=0; i<n; i++) { 67 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 ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr); 89 ierr = PetscLogFlops(2.0*(a->nz) - A->cmap->n);CHKERRQ(ierr); 90 PetscFunctionReturn(0); 91 } 92 93