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.\n\n";

 5:  #include petscmat.h

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

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

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

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

 37:   PetscOptionsHasName(PETSC_NULL,"-keep_zeroed_rows",&keepzeroedrows);
 38:   if (keepzeroedrows) {
 39:     MatSetOption(C,MAT_KEEP_ZEROED_ROWS);
 40:   }

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

 44:   MatView(C,PETSC_VIEWER_STDOUT_SELF);

 46:   ISDestroy(isrow);
 47:   MatDestroy(C);
 48:   PetscFinalize();
 49:   return 0;
 50: }