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;

 27:   PetscFunctionBeginUser;
 28:   PetscCall(PetscInitialize(&argc, &args, NULL, help));
 29:   comm = PETSC_COMM_WORLD;
 30:   PetscCallMPI(MPI_Comm_size(comm, &size));
 31:   PetscOptionsBegin(comm, NULL, "ex193", "hierarchical partitioning");
 32:   m = 15;
 33:   PetscCall(PetscOptionsInt("-M", "Number of mesh points in the x-direction", "partitioning", m, &m, NULL));
 34:   n = 15;
 35:   PetscCall(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:   PetscCall(MatCreate(comm, &A));
 42:   PetscCall(MatSetSizes(A, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
 43:   PetscCall(MatSetFromOptions(A));
 44:   PetscCall(MatSetUp(A));
 45:   PetscCall(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:       PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 53:     }
 54:     if (i < m - 1) {
 55:       J = Ii + n;
 56:       PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 57:     }
 58:     if (j > 0) {
 59:       J = Ii - 1;
 60:       PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 61:     }
 62:     if (j < n - 1) {
 63:       J = Ii + 1;
 64:       PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
 65:     }
 66:     v = 4.0;
 67:     PetscCall(MatSetValues(A, 1, &Ii, 1, &Ii, &v, INSERT_VALUES));
 68:   }
 69:   PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
 70:   PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
 71:   PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
 72:   /*
 73:    Partition the graph of the matrix
 74:   */
 75:   PetscCall(MatPartitioningCreate(comm, &part));
 76:   PetscCall(MatPartitioningSetAdjacency(part, A));
 77:   PetscCall(MatPartitioningSetType(part, MATPARTITIONINGHIERARCH));
 78:   PetscCall(MatPartitioningHierarchicalSetNcoarseparts(part, 2));
 79:   PetscCall(MatPartitioningHierarchicalSetNfineparts(part, 4));
 80:   PetscCall(MatPartitioningSetFromOptions(part));
 81:   /* get new processor owner number of each vertex */
 82:   PetscCall(MatPartitioningApply(part, &is));
 83:   /* coarse parts */
 84:   PetscCall(MatPartitioningHierarchicalGetCoarseparts(part, &coarseparts));
 85:   PetscCall(ISView(coarseparts, PETSC_VIEWER_STDOUT_WORLD));
 86:   /* fine parts */
 87:   PetscCall(MatPartitioningHierarchicalGetFineparts(part, &fineparts));
 88:   PetscCall(ISView(fineparts, PETSC_VIEWER_STDOUT_WORLD));
 89:   /* partitioning */
 90:   PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD));
 91:   /* get new global number of each old global number */
 92:   PetscCall(ISPartitioningToNumbering(is, &isn));
 93:   PetscCall(ISView(isn, PETSC_VIEWER_STDOUT_WORLD));
 94:   PetscCall(ISBuildTwoSided(is, NULL, &isrows));
 95:   PetscCall(ISView(isrows, PETSC_VIEWER_STDOUT_WORLD));
 96:   PetscCall(ISDestroy(&is));
 97:   PetscCall(ISDestroy(&coarseparts));
 98:   PetscCall(ISDestroy(&fineparts));
 99:   PetscCall(ISDestroy(&isrows));
100:   PetscCall(ISDestroy(&isn));
101:   PetscCall(MatPartitioningDestroy(&part));
102:   PetscCall(MatDestroy(&A));
103:   PetscCall(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*/