1
2 static char help[] = "Partition tiny grid.\n\n";
3
4 /*T
5 Concepts: partitioning
6 Processors: 4
7 T*/
8
9 /*
10 Include "petscmat.h" so that we can use matrices. Note that this file
11 automatically includes:
12 petscsys.h - base PETSc routines petscvec.h - vectors
13 petscmat.h - matrices
14 petscis.h - index sets
15 petscviewer.h - viewers
16 */
17 #include <petscmat.h>
18
main(int argc,char ** args)19 int main(int argc,char **args)
20 {
21 Mat A;
22 PetscErrorCode ierr;
23 PetscMPIInt rank,size;
24 PetscInt *ia,*ja;
25 MatPartitioning part;
26 IS is,isn;
27
28 ierr = PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
29 ierr = MPI_Comm_size(PETSC_COMM_WORLD,&size);CHKERRQ(ierr);
30 if (size != 4) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"Must run with 4 processors");
31 ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRQ(ierr);
32
33 ierr = PetscMalloc1(5,&ia);CHKERRQ(ierr);
34 ierr = PetscMalloc1(16,&ja);CHKERRQ(ierr);
35 if (!rank) {
36 ja[0] = 1; ja[1] = 4; ja[2] = 0; ja[3] = 2; ja[4] = 5; ja[5] = 1; ja[6] = 3; ja[7] = 6;
37 ja[8] = 2; ja[9] = 7;
38 ia[0] = 0; ia[1] = 2; ia[2] = 5; ia[3] = 8; ia[4] = 10;
39 } else if (rank == 1) {
40 ja[0] = 0; ja[1] = 5; ja[2] = 8; ja[3] = 1; ja[4] = 4; ja[5] = 6; ja[6] = 9; ja[7] = 2;
41 ja[8] = 5; ja[9] = 7; ja[10] = 10; ja[11] = 3; ja[12] = 6; ja[13] = 11;
42 ia[0] = 0; ia[1] = 3; ia[2] = 7; ia[3] = 11; ia[4] = 14;
43 } else if (rank == 2) {
44 ja[0] = 4; ja[1] = 9; ja[2] = 12; ja[3] = 5; ja[4] = 8; ja[5] = 10; ja[6] = 13; ja[7] = 6;
45 ja[8] = 9; ja[9] = 11; ja[10] = 14; ja[11] = 7; ja[12] = 10; ja[13] = 15;
46 ia[0] = 0; ia[1] = 3; ia[2] = 7; ia[3] = 11; ia[4] = 14;
47 } else {
48 ja[0] = 8; ja[1] = 13; ja[2] = 9; ja[3] = 12; ja[4] = 14; ja[5] = 10; ja[6] = 13; ja[7] = 15;
49 ja[8] = 11; ja[9] = 14;
50 ia[0] = 0; ia[1] = 2; ia[2] = 5; ia[3] = 8; ia[4] = 10;
51 }
52
53 ierr = MatCreateMPIAdj(PETSC_COMM_WORLD,4,16,ia,ja,NULL,&A);CHKERRQ(ierr);
54 ierr = MatView(A,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
55
56 /*
57 Partition the graph of the matrix
58 */
59 ierr = MatPartitioningCreate(PETSC_COMM_WORLD,&part);CHKERRQ(ierr);
60 ierr = MatPartitioningSetAdjacency(part,A);CHKERRQ(ierr);
61 ierr = MatPartitioningSetFromOptions(part);CHKERRQ(ierr);
62 /* get new processor owner number of each vertex */
63 ierr = MatPartitioningApply(part,&is);CHKERRQ(ierr);
64 /* get new global number of each old global number */
65 ierr = ISPartitioningToNumbering(is,&isn);CHKERRQ(ierr);
66 ierr = ISView(isn,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
67 ierr = ISDestroy(&is);CHKERRQ(ierr);
68
69 ierr = ISDestroy(&isn);CHKERRQ(ierr);
70 ierr = MatPartitioningDestroy(&part);CHKERRQ(ierr);
71
72 /*
73 Free work space. All PETSc objects should be destroyed when they
74 are no longer needed.
75 */
76 ierr = MatDestroy(&A);CHKERRQ(ierr);
77
78
79 ierr = PetscFinalize();
80 return ierr;
81 }
82
83