Actual source code: ex8.c
1: /*$Id: ex8.c,v 1.18 2001/08/07 03:03:07 balay Exp $*/
3: static char help[] = "Tests automatic allocation of matrix storage space.nn";
5: #include petscmat.h
7: int main(int argc,char **args)
8: {
9: Mat C;
10: int i,j,m = 3,n = 3,I,J,ierr;
11: PetscScalar v;
12: MatInfo info;
14: PetscInitialize(&argc,&args,(char *)0,help);
15: PetscOptionsGetInt(PETSC_NULL,"-m",&m,PETSC_NULL);
16: PetscOptionsGetInt(PETSC_NULL,"-n",&n,PETSC_NULL);
18: /* create the matrix for the five point stencil, YET AGAIN */
19: MatCreate(PETSC_COMM_SELF,PETSC_DECIDE,PETSC_DECIDE,m*n,m*n,&C);
20: MatSetFromOptions(C);
21: for (i=0; i<m; i++) {
22: for (j=0; j<n; j++) {
23: v = -1.0; I = j + n*i;
24: if (i>0) {J=I-n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
25: if (i<m-1) {J=I+n; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
26: if (j>0) {J=I-1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
27: if (j<n-1) {J=I+1; MatSetValues(C,1,&I,1,&J,&v,INSERT_VALUES);}
28: v = 4.0; MatSetValues(C,1,&I,1,&I,&v,INSERT_VALUES);
29: }
30: }
31: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
32: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
33: MatView(C,PETSC_VIEWER_STDOUT_SELF);
35: MatGetInfo(C,MAT_LOCAL,&info);
36: PetscPrintf(PETSC_COMM_SELF,"matrix nonzeros = %d, allocated nonzeros = %dn",
37: (int)info.nz_used,(int)info.nz_allocated);
39: MatDestroy(C);
40: PetscFinalize();
41: return 0;
42: }