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,&C);
22: MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,N,N);
23: MatSetFromOptions(C);
24: MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY);
25: MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY);
27: /* create right hand side and solution */
29: VecCreateSeq(PETSC_COMM_SELF,N,&u);
30: VecDuplicate(u,&b);
31: VecDuplicate(u,&x);
32: VecSet(u,zero);
33: VecSet(b,zero);
35: VecAssemblyBegin(b);
36: VecAssemblyEnd(b);
39: /* solve linear system */
40: KSPCreate(PETSC_COMM_WORLD,&ksp);
41: KSPSetOperators(ksp,C,C,DIFFERENT_NONZERO_PATTERN);
42: KSPSetFromOptions(ksp);
43: KSPSolve(ksp,b,u);
45: MatMult(C,u,x);
46: VecAXPY(x,mone,b);
47: VecNorm(x,NORM_2,&norm);
48: printf("Norm of residual %g\n",norm);
50: KSPDestroy(ksp);
51: VecDestroy(u);
52: VecDestroy(x);
53: VecDestroy(b);
54: MatDestroy(C);
55: PetscFinalize();
56: return 0;
57: }