1 2 #include <petsc/private/matimpl.h> /*I "petscmat.h" I*/ 3 4 /*@ 5 MatGetColumnVector - Gets the values from a given column of a matrix. 6 7 Not Collective 8 9 Input Parameters: 10 + A - the matrix 11 . yy - the vector 12 - col - the column requested (in global numbering) 13 14 Level: advanced 15 16 Notes: 17 Each processor for which this is called gets the values for its rows. 18 19 Since PETSc matrices are usually stored in compressed row format, this routine 20 will generally be slow. 21 22 The vector must have the same parallel row layout as the matrix. 23 24 Contributed by: Denis Vanderstraeten 25 26 .seealso: MatGetRow(), MatGetDiagonal() 27 28 @*/ 29 PetscErrorCode MatGetColumnVector(Mat A,Vec yy,PetscInt col) 30 { 31 PetscScalar *y; 32 const PetscScalar *v; 33 PetscErrorCode ierr; 34 PetscInt i,j,nz,N,Rs,Re,rs,re; 35 const PetscInt *idx; 36 37 PetscFunctionBegin; 38 PetscValidHeaderSpecific(A,MAT_CLASSID,1); 39 PetscValidHeaderSpecific(yy,VEC_CLASSID,2); 40 if (col < 0) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Requested negative column: %D",col); 41 ierr = MatGetSize(A,NULL,&N);CHKERRQ(ierr); 42 if (col >= N) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_ARG_OUTOFRANGE,"Requested column %D larger than number columns in matrix %D",col,N); 43 ierr = MatGetOwnershipRange(A,&Rs,&Re);CHKERRQ(ierr); 44 ierr = VecGetOwnershipRange(yy,&rs,&re);CHKERRQ(ierr); 45 if (Rs != rs || Re != re) SETERRQ4(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,"Matrix %D %D does not have same ownership range (size) as vector %D %D",Rs,Re,rs,re); 46 47 if (A->ops->getcolumnvector) { 48 ierr = (*A->ops->getcolumnvector)(A,yy,col);CHKERRQ(ierr); 49 } else { 50 ierr = VecSet(yy,0.0);CHKERRQ(ierr); 51 ierr = VecGetArray(yy,&y);CHKERRQ(ierr); 52 53 for (i=Rs; i<Re; i++) { 54 ierr = MatGetRow(A,i,&nz,&idx,&v);CHKERRQ(ierr); 55 if (nz && idx[0] <= col) { 56 /* 57 Should use faster search here 58 */ 59 for (j=0; j<nz; j++) { 60 if (idx[j] >= col) { 61 if (idx[j] == col) y[i-rs] = v[j]; 62 break; 63 } 64 } 65 } 66 ierr = MatRestoreRow(A,i,&nz,&idx,&v);CHKERRQ(ierr); 67 } 68 ierr = VecRestoreArray(yy,&y);CHKERRQ(ierr); 69 } 70 PetscFunctionReturn(0); 71 } 72 73 74 75 76 /*@ 77 MatGetColumnNorms - Gets the norms of each column of a sparse or dense matrix. 78 79 Input Parameter: 80 + A - the matrix 81 - type - NORM_2, NORM_1 or NORM_INFINITY 82 83 Output Parameter: 84 . norms - an array as large as the TOTAL number of columns in the matrix 85 86 Level: intermediate 87 88 Notes: 89 Each process has ALL the column norms after the call. Because of the way this is computed each process gets all the values, 90 if each process wants only some of the values it should extract the ones it wants from the array. 91 92 .seealso: NormType, MatNorm() 93 94 @*/ 95 PetscErrorCode MatGetColumnNorms(Mat A,NormType type,PetscReal norms[]) 96 { 97 PetscErrorCode ierr; 98 99 PetscFunctionBegin; 100 PetscValidHeaderSpecific(A,MAT_CLASSID,1); 101 if (A->ops->getcolumnnorms) { 102 ierr = (*A->ops->getcolumnnorms)(A,type,norms);CHKERRQ(ierr); 103 } else SETERRQ(PetscObjectComm((PetscObject)A),PETSC_ERR_SUP,"Not coded for this matrix type"); 104 PetscFunctionReturn(0); 105 } 106 107