Actual source code: ex2.c
2: /* "$Id: ex2.c,v 1.20 2001/03/23 23:21:14 balay Exp $"; */
4: static char help[] = "Demonstrates creating a stride index set.nn";
6: /*T
7: Concepts: index sets^creating a stride index set;
8: Concepts: stride^creating a stride index set;
9: Concepts: IS^creating a stride index set;
10:
11: Description: Creates an index set based on a stride. Views that index set
12: and then destroys it.
13: T*/
15: /*
16: Include petscis.h so we can use PETSc IS objects. Note that this automatically
17: includes petsc.h.
18: */
20: #include petscis.h
22: int main(int argc,char **argv)
23: {
24: int i,n,ierr, *indices,first,step;
25: IS set;
27: PetscInitialize(&argc,&argv,(char*)0,help);
28:
29: n = 10;
30: first = 3;
31: step = 2;
33: /*
34: Create stride index set, starting at 3 with a stride of 2
35: Note each processor is generating its own index set
36: (in this case they are all identical)
37: */
38: ISCreateStride(PETSC_COMM_SELF,n,first,step,&set);
39: ISView(set,PETSC_VIEWER_STDOUT_SELF);
41: /*
42: Extract indices from set.
43: */
44: ISGetIndices(set,&indices);
45: PetscPrintf(PETSC_COMM_WORLD,"Printing indices directlyn");
46: for (i=0; i<n; i++) {
47: PetscPrintf(PETSC_COMM_WORLD,"%dn",indices[i]);
48: }
50: ISRestoreIndices(set,&indices);
52: /*
53: Determine information on stride
54: */
55: ISStrideGetInfo(set,&first,&step);
56: if (first != 3 || step != 2) SETERRQ(1,"Stride info not correct!n");
57: ISDestroy(set);
58: PetscFinalize();
59: return 0;
60: }