1 static char help[] = "Partition a tiny grid using hierarchical partitioning.\n\n";
2
3 /*
4 Include "petscmat.h" so that we can use matrices. Note that this file
5 automatically includes:
6 petscsys.h - base PETSc routines petscvec.h - vectors
7 petscmat.h - matrices
8 petscis.h - index sets
9 petscviewer.h - viewers
10 */
11 #include <petscmat.h>
12
main(int argc,char ** args)13 int main(int argc, char **args)
14 {
15 Mat A;
16 PetscMPIInt rank, size;
17 PetscInt *ia, *ja;
18 MatPartitioning part;
19 IS is, isn, isrows;
20 IS coarseparts, fineparts;
21 MPI_Comm comm;
22
23 PetscFunctionBeginUser;
24 PetscCall(PetscInitialize(&argc, &args, NULL, help));
25 comm = PETSC_COMM_WORLD;
26 PetscCallMPI(MPI_Comm_size(comm, &size));
27 PetscCheck(size == 4, comm, PETSC_ERR_WRONG_MPI_SIZE, "Must run with 4 processors");
28 PetscCallMPI(MPI_Comm_rank(comm, &rank));
29
30 PetscCall(PetscMalloc1(5, &ia));
31 PetscCall(PetscMalloc1(16, &ja));
32 if (rank == 0) {
33 ja[0] = 1;
34 ja[1] = 4;
35 ja[2] = 0;
36 ja[3] = 2;
37 ja[4] = 5;
38 ja[5] = 1;
39 ja[6] = 3;
40 ja[7] = 6;
41 ja[8] = 2;
42 ja[9] = 7;
43 ia[0] = 0;
44 ia[1] = 2;
45 ia[2] = 5;
46 ia[3] = 8;
47 ia[4] = 10;
48 } else if (rank == 1) {
49 ja[0] = 0;
50 ja[1] = 5;
51 ja[2] = 8;
52 ja[3] = 1;
53 ja[4] = 4;
54 ja[5] = 6;
55 ja[6] = 9;
56 ja[7] = 2;
57 ja[8] = 5;
58 ja[9] = 7;
59 ja[10] = 10;
60 ja[11] = 3;
61 ja[12] = 6;
62 ja[13] = 11;
63 ia[0] = 0;
64 ia[1] = 3;
65 ia[2] = 7;
66 ia[3] = 11;
67 ia[4] = 14;
68 } else if (rank == 2) {
69 ja[0] = 4;
70 ja[1] = 9;
71 ja[2] = 12;
72 ja[3] = 5;
73 ja[4] = 8;
74 ja[5] = 10;
75 ja[6] = 13;
76 ja[7] = 6;
77 ja[8] = 9;
78 ja[9] = 11;
79 ja[10] = 14;
80 ja[11] = 7;
81 ja[12] = 10;
82 ja[13] = 15;
83 ia[0] = 0;
84 ia[1] = 3;
85 ia[2] = 7;
86 ia[3] = 11;
87 ia[4] = 14;
88 } else {
89 ja[0] = 8;
90 ja[1] = 13;
91 ja[2] = 9;
92 ja[3] = 12;
93 ja[4] = 14;
94 ja[5] = 10;
95 ja[6] = 13;
96 ja[7] = 15;
97 ja[8] = 11;
98 ja[9] = 14;
99 ia[0] = 0;
100 ia[1] = 2;
101 ia[2] = 5;
102 ia[3] = 8;
103 ia[4] = 10;
104 }
105 PetscCall(MatCreateMPIAdj(comm, 4, 16, ia, ja, NULL, &A));
106 PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
107 /*
108 Partition the graph of the matrix
109 */
110 PetscCall(MatPartitioningCreate(comm, &part));
111 PetscCall(MatPartitioningSetAdjacency(part, A));
112 PetscCall(MatPartitioningSetType(part, MATPARTITIONINGHIERARCH));
113 PetscCall(MatPartitioningHierarchicalSetNcoarseparts(part, 2));
114 PetscCall(MatPartitioningHierarchicalSetNfineparts(part, 2));
115 PetscCall(MatPartitioningSetFromOptions(part));
116 /* get new processor owner number of each vertex */
117 PetscCall(MatPartitioningApply(part, &is));
118 /* coarse parts */
119 PetscCall(MatPartitioningHierarchicalGetCoarseparts(part, &coarseparts));
120 PetscCall(ISView(coarseparts, PETSC_VIEWER_STDOUT_WORLD));
121 /* fine parts */
122 PetscCall(MatPartitioningHierarchicalGetFineparts(part, &fineparts));
123 PetscCall(ISView(fineparts, PETSC_VIEWER_STDOUT_WORLD));
124 /* partitioning */
125 PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD));
126 /* get new global number of each old global number */
127 PetscCall(ISPartitioningToNumbering(is, &isn));
128 PetscCall(ISView(isn, PETSC_VIEWER_STDOUT_WORLD));
129 PetscCall(ISBuildTwoSided(is, NULL, &isrows));
130 PetscCall(ISView(isrows, PETSC_VIEWER_STDOUT_WORLD));
131 PetscCall(ISDestroy(&is));
132 PetscCall(ISDestroy(&coarseparts));
133 PetscCall(ISDestroy(&fineparts));
134 PetscCall(ISDestroy(&isrows));
135 PetscCall(ISDestroy(&isn));
136 PetscCall(MatPartitioningDestroy(&part));
137 /*
138 Free work space. All PETSc objects should be destroyed when they
139 are no longer needed.
140 */
141 PetscCall(MatDestroy(&A));
142 PetscCall(PetscFinalize());
143 return 0;
144 }
145
146 /*TEST
147
148 test:
149 nsize: 4
150 requires: parmetis
151 TODO: tests cannot use parmetis because it produces different results on different machines
152
153 TEST*/
154