Actual source code: ex3.c
2: static char help[] = "Demonstrates creating a blocked index set.\n\n";
4: /*T
5: Concepts: index sets^creating a block index set;
6: Concepts: IS^creating a block index set;
8: Description: Creates an index set based on blocks of integers. Views that index set
9: and then destroys it.
10: T*/
12: #include <petscis.h>
13: #include <petscviewer.h>
15: int main(int argc,char **argv)
16: {
17: PetscInt i,n = 4, inputindices[] = {0,1,3,4},bs = 3,issize;
18: const PetscInt *indices;
19: IS set;
20: PetscBool isblock;
22: PetscInitialize(&argc,&argv,(char*)0,help);
24: /*
25: Create a block index set. The index set has 4 blocks each of size 3.
26: The indices are {0,1,2,3,4,5,9,10,11,12,13,14}
27: Note each processor is generating its own index set
28: (in this case they are all identical)
29: */
30: ISCreateBlock(PETSC_COMM_SELF,bs,n,inputindices,PETSC_COPY_VALUES,&set);
31: ISView(set,PETSC_VIEWER_STDOUT_SELF);
33: /*
34: Extract indices from set.
35: */
36: ISGetLocalSize(set,&issize);
37: ISGetIndices(set,&indices);
38: PetscPrintf(PETSC_COMM_SELF,"Printing indices directly\n");
39: for (i=0; i<issize; i++) {
40: PetscPrintf(PETSC_COMM_SELF,"%" PetscInt_FMT "\n",indices[i]);
41: }
42: ISRestoreIndices(set,&indices);
44: /*
45: Extract the block indices. This returns one index per block.
46: */
47: ISBlockGetIndices(set,&indices);
48: PetscPrintf(PETSC_COMM_SELF,"Printing block indices directly\n");
49: for (i=0; i<n; i++) {
50: PetscPrintf(PETSC_COMM_SELF,"%" PetscInt_FMT "\n",indices[i]);
51: }
52: ISBlockRestoreIndices(set,&indices);
54: /*
55: Check if this is really a block index set
56: */
57: PetscObjectTypeCompare((PetscObject)set,ISBLOCK,&isblock);
60: /*
61: Determine the block size of the index set
62: */
63: ISGetBlockSize(set,&bs);
66: /*
67: Get the number of blocks
68: */
69: ISBlockGetLocalSize(set,&n);
72: ISDestroy(&set);
73: PetscFinalize();
74: return 0;
75: }
77: /*TEST
79: test:
81: TEST*/