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;
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 petscsys.h.
16: */
18: #include <petscis.h>
19: #include <petscviewer.h>
21: int main(int argc,char **argv)
22: {
24: PetscInt i,n,first,step;
25: IS set;
26: const PetscInt *indices;
28: PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
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(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Stride info not correct!\n");
58: ISDestroy(&set);
59: PetscFinalize();
60: return ierr;
61: }
63: /*TEST
65: test:
67: TEST*/