Actual source code: ex2.c
2: static char help[] = "Demonstrates creating a stride index set.\n\n";
4: /*T
5: Concepts: index sets^creating a stride index set;
6: Concepts: stride^creating a stride index set;
7: Concepts: IS^creating a stride index set;
8:
9: Description: Creates an index set based on a stride. Views that index set
10: and then destroys it.
11: T*/
13: /*
14: Include petscis.h so we can use PETSc IS objects. Note that this automatically
15: includes petsc.h.
16: */
18: #include petscis.h
22: int main(int argc,char **argv)
23: {
25: PetscInt i,n,*indices,first,step;
26: IS set;
28: PetscInitialize(&argc,&argv,(char*)0,help);
29:
30: n = 10;
31: first = 3;
32: step = 2;
34: /*
35: Create stride index set, starting at 3 with a stride of 2
36: Note each processor is generating its own index set
37: (in this case they are all identical)
38: */
39: ISCreateStride(PETSC_COMM_SELF,n,first,step,&set);
40: ISView(set,PETSC_VIEWER_STDOUT_SELF);
42: /*
43: Extract indices from set.
44: */
45: ISGetIndices(set,&indices);
46: PetscPrintf(PETSC_COMM_WORLD,"Printing indices directly\n");
47: for (i=0; i<n; i++) {
48: PetscPrintf(PETSC_COMM_WORLD,"%D\n",indices[i]);
49: }
51: ISRestoreIndices(set,&indices);
53: /*
54: Determine information on stride
55: */
56: ISStrideGetInfo(set,&first,&step);
57: if (first != 3 || step != 2) SETERRQ(1,"Stride info not correct!\n");
58: ISDestroy(set);
59: PetscFinalize();
60: return 0;
61: }