1 /*$Id: getcolv.c,v 1.10 2000/04/09 04:36:57 bsmith Exp bsmith $*/ 2 3 #include "src/mat/matimpl.h" /*I "mat.h" I*/ 4 5 #undef __FUNC__ 6 #define __FUNC__ /*<a name=""></a>*/"MatGetColumnVector" 7 /*@ 8 MatGetColumnVector - Gets the values from a given column of a matrix. 9 10 Collective on Mat and Vec 11 12 Input Parameters: 13 + X - the matrix 14 . v - the vector 15 - c - the column requested 16 17 Level: advanced 18 19 Contributed by: Denis Vanderstraeten 20 21 .keywords: matrix, column, get 22 23 .seealso: MatGetRow(), MatGetDiagonal() 24 25 @*/ 26 int MatGetColumnVector(Mat A,Vec yy,int col) 27 { 28 Scalar *y,*v,zero = 0.0; 29 int ierr,i,j,nz,*idx,M,N,Mv,Rs,Re,rs,re; 30 31 PetscFunctionBegin; 32 PetscValidHeaderSpecific(A,MAT_COOKIE); 33 PetscValidHeaderSpecific(yy,VEC_COOKIE); 34 35 if (col < 0) SETERRQ1(1,1,"Requested negative column: %d",col); 36 ierr = MatGetSize(A,&M,&N);CHKERRQ(ierr); 37 if (col >= N) SETERRQ2(1,1,"Requested column %d larger than number columns in matrix %d",col,N); 38 39 ierr = VecGetSize(yy,&Mv);CHKERRQ(ierr); 40 if (M != Mv) SETERRQ2(1,1,"Matrix does not have same number of columns %d as vector %d",M,Mv); 41 42 ierr = MatGetOwnershipRange(A,&Rs,&Re);CHKERRQ(ierr); 43 ierr = VecGetOwnershipRange(yy,&rs,&re);CHKERRQ(ierr); 44 if (Rs != rs || Re != re) SETERRQ4(1,1,"Matrix %d %d does not have same ownership range as vector %d %d",Rs,Re,rs,re); 45 46 ierr = VecSet(&zero,yy);CHKERRQ(ierr); 47 ierr = VecGetArray(yy,&y);CHKERRQ(ierr); 48 49 for (i=Rs; i<Re; i++) { 50 ierr = MatGetRow(A,i,&nz,&idx,&v);CHKERRQ(ierr); 51 if (nz && idx[0] <= col) { 52 /* 53 Should use faster search here 54 */ 55 for (j=0; j<nz; j++) { 56 if (idx[j] >= col) { 57 if (idx[j] == col) y[i-rs] = v[j]; 58 break; 59 } 60 } 61 } 62 ierr = MatRestoreRow(A,i,&nz,&idx,&v);CHKERRQ(ierr); 63 } 64 65 ierr = VecRestoreArray(yy,&y);CHKERRQ(ierr); 66 PetscFunctionReturn(0); 67 } 68