1*3d81755aSBarry Smith /*$Id: getcolv.c,v 1.22 2001/08/08 15:46:54 bsmith Exp bsmith $*/ 20925cdddSBarry Smith 3e090d566SSatish Balay #include "src/mat/matimpl.h" /*I "petscmat.h" I*/ 40925cdddSBarry Smith 54a2ae208SSatish Balay #undef __FUNCT__ 64a2ae208SSatish Balay #define __FUNCT__ "MatGetColumnVector" 70925cdddSBarry Smith /*@ 882bf6240SBarry Smith MatGetColumnVector - Gets the values from a given column of a matrix. 90925cdddSBarry Smith 1072257631SBarry Smith Not Collective 11fee21e36SBarry Smith 1298a79cdbSBarry Smith Input Parameters: 135ed6d96aSBarry Smith + A - the matrix 145ed6d96aSBarry Smith . yy - the vector 155ed6d96aSBarry Smith - c - the column requested (in global numbering) 1698a79cdbSBarry Smith 1715091d37SBarry Smith Level: advanced 1815091d37SBarry Smith 199d006df2SBarry Smith Notes: 209d006df2SBarry Smith Each processor for which this is called gets the values for its rows. 219d006df2SBarry Smith 229d006df2SBarry Smith Since PETSc matrices are usually stored in compressed row format, this routine 239d006df2SBarry Smith will generally be slow. 249d006df2SBarry Smith 25*3d81755aSBarry Smith The vector must have the same parallel row layout as the matrix. 26*3d81755aSBarry Smith 2782bf6240SBarry Smith Contributed by: Denis Vanderstraeten 280925cdddSBarry Smith 2982bf6240SBarry Smith .keywords: matrix, column, get 300925cdddSBarry Smith 3115091d37SBarry Smith .seealso: MatGetRow(), MatGetDiagonal() 3215091d37SBarry Smith 330925cdddSBarry Smith @*/ 3482bf6240SBarry Smith int MatGetColumnVector(Mat A,Vec yy,int col) 350925cdddSBarry Smith { 36ea709b57SSatish Balay PetscScalar *y,*v,zero = 0.0; 374a2ae208SSatish Balay int ierr,i,j,nz,*idx,N,Rs,Re,rs,re; 38011b8408SBarry Smith MPI_Comm comm; 390925cdddSBarry Smith 400925cdddSBarry Smith PetscFunctionBegin; 4182bf6240SBarry Smith PetscValidHeaderSpecific(A,MAT_COOKIE); 4282bf6240SBarry Smith PetscValidHeaderSpecific(yy,VEC_COOKIE); 430925cdddSBarry Smith 4429bbc08cSBarry Smith if (col < 0) SETERRQ1(1,"Requested negative column: %d",col); 45011b8408SBarry Smith ierr = MatGetSize(A,PETSC_NULL,&N);CHKERRQ(ierr); 4629bbc08cSBarry Smith if (col >= N) SETERRQ2(1,"Requested column %d larger than number columns in matrix %d",col,N); 470925cdddSBarry Smith 4882bf6240SBarry Smith ierr = MatGetOwnershipRange(A,&Rs,&Re);CHKERRQ(ierr); 49011b8408SBarry Smith 50011b8408SBarry Smith ierr = PetscObjectGetComm((PetscObject)yy,&comm);CHKERRQ(ierr); 5182bf6240SBarry Smith ierr = VecGetOwnershipRange(yy,&rs,&re);CHKERRQ(ierr); 5229bbc08cSBarry Smith if (Rs != rs || Re != re) SETERRQ4(1,"Matrix %d %d does not have same ownership range (size) as vector %d %d",Rs,Re,rs,re); 5382bf6240SBarry Smith 5482bf6240SBarry Smith ierr = VecSet(&zero,yy);CHKERRQ(ierr); 5582bf6240SBarry Smith ierr = VecGetArray(yy,&y);CHKERRQ(ierr); 5682bf6240SBarry Smith 5782bf6240SBarry Smith for (i=Rs; i<Re; i++) { 5882bf6240SBarry Smith ierr = MatGetRow(A,i,&nz,&idx,&v);CHKERRQ(ierr); 5982bf6240SBarry Smith if (nz && idx[0] <= col) { 6082bf6240SBarry Smith /* 6182bf6240SBarry Smith Should use faster search here 6282bf6240SBarry Smith */ 6382bf6240SBarry Smith for (j=0; j<nz; j++) { 6482bf6240SBarry Smith if (idx[j] >= col) { 6582bf6240SBarry Smith if (idx[j] == col) y[i-rs] = v[j]; 6682bf6240SBarry Smith break; 670925cdddSBarry Smith } 680925cdddSBarry Smith } 690925cdddSBarry Smith } 7082bf6240SBarry Smith ierr = MatRestoreRow(A,i,&nz,&idx,&v);CHKERRQ(ierr); 710925cdddSBarry Smith } 720925cdddSBarry Smith 7382bf6240SBarry Smith ierr = VecRestoreArray(yy,&y);CHKERRQ(ierr); 740925cdddSBarry Smith PetscFunctionReturn(0); 750925cdddSBarry Smith } 76