Actual source code: ex193.c
1: /*
2: * ex193.c
3: *
4: * Created on: Jul 29, 2015
5: * Author: Fande Kong fdkong.jd@gmail.com
6: */
7: /*
8: * An example demonstrates how to use hierarchical partitioning approach
9: */
11: #include <petscmat.h>
13: static char help[] = "Illustrates use of hierarchical partitioning.\n";
15: int main(int argc, char **args)
16: {
17: Mat A; /* matrix */
18: PetscInt m, n; /* mesh dimensions in x- and y- directions */
19: PetscInt i, j, Ii, J, Istart, Iend;
20: PetscMPIInt size;
21: PetscScalar v;
22: MatPartitioning part;
23: IS coarseparts, fineparts;
24: IS is, isn, isrows;
25: MPI_Comm comm;
28: PetscInitialize(&argc, &args, (char *)0, help);
29: comm = PETSC_COMM_WORLD;
30: MPI_Comm_size(comm, &size);
31: PetscOptionsBegin(comm, NULL, "ex193", "hierarchical partitioning");
32: m = 15;
33: PetscOptionsInt("-M", "Number of mesh points in the x-direction", "partitioning", m, &m, NULL);
34: n = 15;
35: PetscOptionsInt("-N", "Number of mesh points in the y-direction", "partitioning", n, &n, NULL);
36: PetscOptionsEnd();
38: /*
39: Assemble the matrix for the five point stencil (finite difference), YET AGAIN
40: */
41: MatCreate(comm, &A);
42: MatSetSizes(A, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n);
43: MatSetFromOptions(A);
44: MatSetUp(A);
45: MatGetOwnershipRange(A, &Istart, &Iend);
46: for (Ii = Istart; Ii < Iend; Ii++) {
47: v = -1.0;
48: i = Ii / n;
49: j = Ii - i * n;
50: if (i > 0) {
51: J = Ii - n;
52: MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES);
53: }
54: if (i < m - 1) {
55: J = Ii + n;
56: MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES);
57: }
58: if (j > 0) {
59: J = Ii - 1;
60: MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES);
61: }
62: if (j < n - 1) {
63: J = Ii + 1;
64: MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES);
65: }
66: v = 4.0;
67: MatSetValues(A, 1, &Ii, 1, &Ii, &v, INSERT_VALUES);
68: }
69: MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY);
70: MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY);
71: MatView(A, PETSC_VIEWER_STDOUT_WORLD);
72: /*
73: Partition the graph of the matrix
74: */
75: MatPartitioningCreate(comm, &part);
76: MatPartitioningSetAdjacency(part, A);
77: MatPartitioningSetType(part, MATPARTITIONINGHIERARCH);
78: MatPartitioningHierarchicalSetNcoarseparts(part, 2);
79: MatPartitioningHierarchicalSetNfineparts(part, 4);
80: MatPartitioningSetFromOptions(part);
81: /* get new processor owner number of each vertex */
82: MatPartitioningApply(part, &is);
83: /* coarse parts */
84: MatPartitioningHierarchicalGetCoarseparts(part, &coarseparts);
85: ISView(coarseparts, PETSC_VIEWER_STDOUT_WORLD);
86: /* fine parts */
87: MatPartitioningHierarchicalGetFineparts(part, &fineparts);
88: ISView(fineparts, PETSC_VIEWER_STDOUT_WORLD);
89: /* partitioning */
90: ISView(is, PETSC_VIEWER_STDOUT_WORLD);
91: /* get new global number of each old global number */
92: ISPartitioningToNumbering(is, &isn);
93: ISView(isn, PETSC_VIEWER_STDOUT_WORLD);
94: ISBuildTwoSided(is, NULL, &isrows);
95: ISView(isrows, PETSC_VIEWER_STDOUT_WORLD);
96: ISDestroy(&is);
97: ISDestroy(&coarseparts);
98: ISDestroy(&fineparts);
99: ISDestroy(&isrows);
100: ISDestroy(&isn);
101: MatPartitioningDestroy(&part);
102: MatDestroy(&A);
103: PetscFinalize();
104: return 0;
105: }
107: /*TEST
109: test:
110: nsize: 4
111: args: -mat_partitioning_hierarchical_Nfineparts 2
112: requires: parmetis
113: TODO: cannot run because parmetis does reproduce across all machines, probably due to nonportable random number generator
115: TEST*/