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: }