Actual source code: ex3.c
2: static char help[] = "Demonstrates the use of fast Richardson for SOR. And\n\
3: also tests the MatSOR() routines. Input parameters are:\n\
4: -n <n> : problem dimension\n\n";
6: #include <petscksp.h>
7: #include <petscpc.h>
9: int main(int argc, char **args)
10: {
11: Mat mat; /* matrix */
12: Vec b, ustar, u; /* vectors (RHS, exact solution, approx solution) */
13: PC pc; /* PC context */
14: KSP ksp; /* KSP context */
15: PetscInt n = 10, i, its, col[3];
16: PetscScalar value[3];
17: KSPType kspname;
18: PCType pcname;
20: PetscFunctionBeginUser;
21: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
22: PetscCall(PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL));
24: /* Create and initialize vectors */
25: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &b));
26: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &ustar));
27: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &u));
28: PetscCall(VecSet(ustar, 1.0));
29: PetscCall(VecSet(u, 0.0));
31: /* Create and assemble matrix */
32: PetscCall(MatCreate(PETSC_COMM_SELF, &mat));
33: PetscCall(MatSetType(mat, MATSEQAIJ));
34: PetscCall(MatSetSizes(mat, n, n, n, n));
35: PetscCall(MatSetFromOptions(mat));
36: PetscCall(MatSeqAIJSetPreallocation(mat, 3, NULL));
37: PetscCall(MatSeqBAIJSetPreallocation(mat, 1, 3, NULL));
38: PetscCall(MatSeqSBAIJSetPreallocation(mat, 1, 3, NULL));
39: PetscCall(MatSeqSELLSetPreallocation(mat, 3, NULL));
40: value[0] = -1.0;
41: value[1] = 2.0;
42: value[2] = -1.0;
43: for (i = 1; i < n - 1; i++) {
44: col[0] = i - 1;
45: col[1] = i;
46: col[2] = i + 1;
47: PetscCall(MatSetValues(mat, 1, &i, 3, col, value, INSERT_VALUES));
48: }
49: i = n - 1;
50: col[0] = n - 2;
51: col[1] = n - 1;
52: PetscCall(MatSetValues(mat, 1, &i, 2, col, value, INSERT_VALUES));
53: i = 0;
54: col[0] = 0;
55: col[1] = 1;
56: value[0] = 2.0;
57: value[1] = -1.0;
58: PetscCall(MatSetValues(mat, 1, &i, 2, col, value, INSERT_VALUES));
59: PetscCall(MatAssemblyBegin(mat, MAT_FINAL_ASSEMBLY));
60: PetscCall(MatAssemblyEnd(mat, MAT_FINAL_ASSEMBLY));
62: /* Compute right-hand-side vector */
63: PetscCall(MatMult(mat, ustar, b));
65: /* Create PC context and set up data structures */
66: PetscCall(PCCreate(PETSC_COMM_WORLD, &pc));
67: PetscCall(PCSetType(pc, PCNONE));
68: PetscCall(PCSetFromOptions(pc));
69: PetscCall(PCSetOperators(pc, mat, mat));
70: PetscCall(PCSetUp(pc));
72: /* Create KSP context and set up data structures */
73: PetscCall(KSPCreate(PETSC_COMM_WORLD, &ksp));
74: PetscCall(KSPSetType(ksp, KSPRICHARDSON));
75: PetscCall(KSPSetFromOptions(ksp));
76: PetscCall(PCSetOperators(pc, mat, mat));
77: PetscCall(KSPSetPC(ksp, pc));
78: PetscCall(KSPSetUp(ksp));
80: /* Solve the problem */
81: PetscCall(KSPGetType(ksp, &kspname));
82: PetscCall(PCGetType(pc, &pcname));
83: PetscCall(PetscPrintf(PETSC_COMM_SELF, "Running %s with %s preconditioning\n", kspname, pcname));
84: PetscCall(KSPSolve(ksp, b, u));
85: PetscCall(KSPGetIterationNumber(ksp, &its));
86: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Number of iterations %" PetscInt_FMT "\n", its));
88: /* Free data structures */
89: PetscCall(KSPDestroy(&ksp));
90: PetscCall(VecDestroy(&u));
91: PetscCall(VecDestroy(&ustar));
92: PetscCall(VecDestroy(&b));
93: PetscCall(MatDestroy(&mat));
94: PetscCall(PCDestroy(&pc));
95: PetscCall(PetscFinalize());
96: return 0;
97: }
99: /*TEST
101: testset:
102: args: -ksp_type gmres -ksp_monitor_short -pc_type sor -pc_sor_symmetric
103: output_file: output/ex3_1.out
104: test:
105: suffix: sor_aij
106: test:
107: suffix: sor_seqbaij
108: args: -mat_type seqbaij
109: test:
110: suffix: sor_seqsbaij
111: args: -mat_type seqbaij
112: test:
113: suffix: sor_seqsell
114: args: -mat_type seqsell
116: TEST*/