Actual source code: ex4.c
petsc-3.6.1 2015-08-06
2: static char help[] = "Demonstrates the use of fast Richardson for SOR. And tests\n\
3: the MatSOR() routines.\n\n";
5: #include <petscpc.h>
9: int main(int argc,char **args)
10: {
11: Mat mat;
12: Vec b,u;
13: PC pc;
15: PetscInt n = 5,i,col[3];
16: PetscScalar value[3];
18: PetscInitialize(&argc,&args,(char*)0,help);
20: /* Create vectors */
21: VecCreateSeq(PETSC_COMM_SELF,n,&b);
22: VecCreateSeq(PETSC_COMM_SELF,n,&u);
24: /* Create and assemble matrix */
25: MatCreateSeqDense(PETSC_COMM_SELF,n,n,NULL,&mat);
26: value[0] = -1.0; value[1] = 2.0; value[2] = -1.0;
27: for (i=1; i<n-1; i++) {
28: col[0] = i-1; col[1] = i; col[2] = i+1;
29: MatSetValues(mat,1,&i,3,col,value,INSERT_VALUES);
30: }
31: i = n - 1; col[0] = n - 2; col[1] = n - 1;
32: MatSetValues(mat,1,&i,2,col,value,INSERT_VALUES);
33: i = 0; col[0] = 0; col[1] = 1; value[0] = 2.0; value[1] = -1.0;
34: MatSetValues(mat,1,&i,2,col,value,INSERT_VALUES);
35: MatAssemblyBegin(mat,MAT_FINAL_ASSEMBLY);
36: MatAssemblyEnd(mat,MAT_FINAL_ASSEMBLY);
38: /* Create PC context and set up data structures */
39: PCCreate(PETSC_COMM_WORLD,&pc);
40: PCSetType(pc,PCSOR);
41: PCSetFromOptions(pc);
42: PCSetOperators(pc,mat,mat);
43: PCSetUp(pc);
45: value[0] = 1.0;
46: for (i=0; i<n; i++) {
47: VecSet(u,0.0);
48: VecSetValues(u,1,&i,value,INSERT_VALUES);
49: VecAssemblyBegin(u);
50: VecAssemblyEnd(u);
51: PCApply(pc,u,b);
52: VecView(b,PETSC_VIEWER_STDOUT_SELF);
53: }
55: /* Free data structures */
56: MatDestroy(&mat);
57: PCDestroy(&pc);
58: VecDestroy(&u);
59: VecDestroy(&b);
60: PetscFinalize();
61: return 0;
62: }