Actual source code: ex11.c

  1: /*$Id: ex11.c,v 1.18 2001/08/07 03:03:07 balay Exp $*/

  3: static char help[] = "Tests the use of MatZeroRows() for uniprocessor matrices.nn";

 5:  #include petscmat.h

  7: int main(int argc,char **args)
  8: {
  9:   Mat         C;
 10:   int         i,j,m = 5,n = 5,I,J,ierr;
 11:   PetscScalar v,five = 5.0;
 12:   IS          isrow;
 13:   PetscTruth  keepzeroedrows;

 15:   PetscInitialize(&argc,&args,(char *)0,help);

 17:   /* create the matrix for the five point stencil, YET AGAIN*/
 18:   MatCreate(PETSC_COMM_SELF,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n,&C);
 19:   MatSetFromOptions(C);
 20:   for (i=0; i<m; i++) {
 21:     for (j=0; j<n; j++) {
 22:       v = -1.0;  I = j + n*i;
 23:       if (i>0)   {J = I - n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 24:       if (i<m-1) {J = I + n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 25:       if (j>0)   {J = I - 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 26:       if (j<n-1) {J = I + 1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
 27:       v = 4.0; MatSetValues(C,1,&I,1,&I,&v,INSERT_VALUES);
 28:     }
 29:   }
 30:   MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
 31:   MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);

 33:   ISCreateStride(PETSC_COMM_SELF,(m*n)/2,0,2,&isrow);

 35:   PetscOptionsHasName(PETSC_NULL,"-keep_zeroed_rows",&keepzeroedrows);
 36:   if (keepzeroedrows) {
 37:     MatSetOption(C,MAT_KEEP_ZEROED_ROWS);
 38:   }

 40:   MatZeroRows(C,isrow,&five);

 42:   MatView(C,PETSC_VIEWER_STDOUT_SELF);

 44:   ISDestroy(isrow);
 45:   MatDestroy(C);
 46:   PetscFinalize();
 47:   return 0;
 48: }