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: }