1 #ifdef PETSC_RCS_HEADER 2 static char vcid[] = "$Id: getcolv.c,v 1.3 1998/04/13 17:43:46 bsmith Exp bsmith $"; 3 #endif 4 5 #include "src/mat/matimpl.h" /*I "mat.h" I*/ 6 7 #undef __FUNC__ 8 #define __FUNC__ "MatGetColumnVector" 9 /*@ 10 MatGetColumnVector - Gets the values from a given column of a matrix. 11 12 Collective on Mat and Vec 13 14 Input Parameters: 15 + X - the matrix 16 . v - the vector 17 - c - the column requested 18 19 Contributed by: Denis Vanderstraeten 20 21 .keywords: matrix, column, get 22 23 @*/ 24 int MatGetColumnVector(Mat A, Vec yy, int col) 25 { 26 Scalar *y,*v,zero = 0.0; 27 int ierr,i,j,nz,*idx,M,N,Mv,Rs,Re,rs,re; 28 29 PetscFunctionBegin; 30 PetscValidHeaderSpecific(A,MAT_COOKIE); 31 PetscValidHeaderSpecific(yy,VEC_COOKIE); 32 33 if (col < 0) SETERRQ(1,1,"Requested negative column"); 34 ierr = MatGetSize(A,&M,&N); CHKERRQ(ierr); 35 if (col >= N) SETERRQ(1,1,"Requested column larger than number columns in matrix"); 36 37 ierr = VecGetSize(yy,&Mv); CHKERRQ(ierr); 38 if (M != Mv) SETERRQ(1,1,"Matrix does not have same number of columns as vector"); 39 40 ierr = MatGetOwnershipRange(A,&Rs,&Re);CHKERRQ(ierr); 41 ierr = VecGetOwnershipRange(yy,&rs,&re);CHKERRQ(ierr); 42 if (Rs != rs || Re != re) SETERRQ(1,1,"Matrix does not have same ownership range as vector"); 43 44 ierr = VecSet(&zero,yy);CHKERRQ(ierr); 45 ierr = VecGetArray(yy,&y);CHKERRQ(ierr); 46 47 for ( i=Rs; i<Re; i++ ) { 48 ierr = MatGetRow(A,i,&nz,&idx,&v);CHKERRQ(ierr); 49 if (nz && idx[0] <= col) { 50 /* 51 Should use faster search here 52 */ 53 for ( j=0; j<nz; j++ ) { 54 if (idx[j] >= col) { 55 if (idx[j] == col) y[i-rs] = v[j]; 56 break; 57 } 58 } 59 } 60 ierr = MatRestoreRow(A,i,&nz,&idx,&v);CHKERRQ(ierr); 61 } 62 63 ierr = VecRestoreArray(yy,&y);CHKERRQ(ierr); 64 PetscFunctionReturn(0); 65 } 66