Actual source code: ex1.c
2: static char help[] = "Tests solving linear system on 0 by 0 matrix.\n\n";
4: #include petscksp.h
8: int main(int argc,char **args)
9: {
10: Mat C;
12: PetscInt N = 0;
13: Vec u,b,x;
14: KSP ksp;
15: PetscScalar zero = 0.0,mone = -1.0;
16: PetscReal norm;
18: PetscInitialize(&argc,&args,(char *)0,help);
20: /* create stiffness matrix */
21: MatCreate(PETSC_COMM_SELF,PETSC_DECIDE,PETSC_DECIDE,N,N,&C);
22: MatSetFromOptions(C);
23: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
24: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
26: /* create right hand side and solution */
28: VecCreateSeq(PETSC_COMM_SELF,N,&u);
29: VecDuplicate(u,&b);
30: VecDuplicate(u,&x);
31: VecSet(&zero,u);
32: VecSet(&zero,b);
34: VecAssemblyBegin(b);
35: VecAssemblyEnd(b);
38: /* solve linear system */
39: KSPCreate(PETSC_COMM_WORLD,&ksp);
40: KSPSetOperators(ksp,C,C,DIFFERENT_NONZERO_PATTERN);
41: KSPSetFromOptions(ksp);
42: KSPSolve(ksp,b,u);
44: MatMult(C,u,x);
45: VecAXPY(&mone,b,x);
46: VecNorm(x,NORM_2,&norm);
47: printf("Norm of residual %g\n",norm);
49: KSPDestroy(ksp);
50: VecDestroy(u);
51: VecDestroy(x);
52: VecDestroy(b);
53: MatDestroy(C);
54: PetscFinalize();
55: return 0;
56: }