Actual source code: ex60.c
petsc-3.4.2 2013-07-02

      2: static char help[] = "Tests MatGetColumnVector().";

      4: #include <petscmat.h>

      8: int main(int argc,char **args)
      9: {
     10:   Mat            C;
     11:   PetscInt       i,j,m = 3,n = 2,Ii,J,col = 0;
     12:   PetscMPIInt    size,rank;
     14:   PetscScalar    v;
     15:   Vec            yy;

     17:   PetscInitialize(&argc,&args,(char*)0,help);
     18:   PetscOptionsGetInt(NULL,"-col",&col,NULL);

     20:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
     21:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
     22:   n    = 2*size;

     24:   /* create the matrix for the five point stencil, YET AGAIN*/
     25:   MatCreateAIJ(PETSC_COMM_WORLD,PETSC_DECIDE,PETSC_DECIDE,
     26:                       m*n,m*n,5,NULL,5,NULL,&C);
     27:   for (i=0; i<m; i++) {
     28:     for (j=2*rank; j<2*rank+2; j++) {
     29:       v = -1.0;  Ii = j + n*i;
     30:       if (i>0)   {J = Ii - n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
     31:       if (i<m-1) {J = Ii + n; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
     32:       if (j>0)   {J = Ii - 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
     33:       if (j<n-1) {J = Ii + 1; MatSetValues(C,1,&Ii,1,&J,&v,INSERT_VALUES);}
     34:       v = 4.0; MatSetValues(C,1,&Ii,1,&Ii,&v,INSERT_VALUES);
     35:     }
     36:   }
     37:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
     38:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
     39:   MatView(C,PETSC_VIEWER_STDOUT_WORLD);

     41:   VecCreate(PETSC_COMM_WORLD,&yy);
     42:   VecSetSizes(yy,PETSC_DECIDE,m*n);
     43:   VecSetFromOptions(yy);

     45:   MatGetColumnVector(C,yy,col);

     47:   VecView(yy,PETSC_VIEWER_STDOUT_WORLD);

     49:   VecDestroy(&yy);
     50:   MatDestroy(&C);
     51:   PetscFinalize();
     52:   return 0;
     53: }