Actual source code: ex1.c
1: /*$Id: ex1.c,v 1.18 2001/08/07 21:30:50 bsmith Exp $*/
3: static char help[] = "Tests solving linear system on 0 by 0 matrix.nn";
5: #include petscsles.h
7: int main(int argc,char **args)
8: {
9: Mat C;
10: int ierr,N = 0,its;
11: Vec u,b,x;
12: SLES sles;
13: PetscScalar zero = 0.0,mone = -1.0;
14: PetscReal norm;
16: PetscInitialize(&argc,&args,(char *)0,help);
18: /* create stiffness matrix */
19: MatCreate(PETSC_COMM_SELF,PETSC_DECIDE,PETSC_DECIDE,N,N,&C);
20: MatSetFromOptions(C);
21: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
22: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
24: /* create right hand side and solution */
26: VecCreateSeq(PETSC_COMM_SELF,N,&u);
27: VecDuplicate(u,&b);
28: VecDuplicate(u,&x);
29: VecSet(&zero,u);
30: VecSet(&zero,b);
32: VecAssemblyBegin(b);
33: VecAssemblyEnd(b);
36: /* solve linear system */
37: SLESCreate(PETSC_COMM_WORLD,&sles);
38: SLESSetOperators(sles,C,C,DIFFERENT_NONZERO_PATTERN);
39: SLESSetFromOptions(sles);
40: SLESSolve(sles,b,u,&its);
42: MatMult(C,u,x);
43: VecAXPY(&mone,b,x);
44: VecNorm(x,NORM_2,&norm);
45: printf("Norm of residual %gn",norm);
47: SLESDestroy(sles);
48: VecDestroy(u);
49: VecDestroy(x);
50: VecDestroy(b);
51: MatDestroy(C);
52: PetscFinalize();
53: return 0;
54: }