1: static char help[] = "Partition a tiny grid using hierarchical partitioning.\n\n";

  3: /*
  4:   Include "petscmat.h" so that we can use matrices.  Note that this file
  5:   automatically includes:
  6:      petscsys.h - base PETSc routines
  7:      petscvec.h - vectors
  8:      petscis.h  - index sets
  9: */
 10: #include <petscmat.h>

 12: int main(int argc, char **args)
 13: {
 14:   Mat             A;
 15:   PetscMPIInt     rank, size;
 16:   PetscInt       *ia, *ja;
 17:   MatPartitioning part;
 18:   IS              is, isn, isrows;
 19:   IS              coarseparts, fineparts;
 20:   MPI_Comm        comm;

 22:   PetscFunctionBeginUser;
 23:   PetscCall(PetscInitialize(&argc, &args, NULL, help));
 24:   comm = PETSC_COMM_WORLD;
 25:   PetscCallMPI(MPI_Comm_size(comm, &size));
 26:   PetscCheck(size == 4, comm, PETSC_ERR_WRONG_MPI_SIZE, "Must run with 4 processors");
 27:   PetscCallMPI(MPI_Comm_rank(comm, &rank));

 29:   PetscCall(PetscMalloc1(5, &ia));
 30:   PetscCall(PetscMalloc1(16, &ja));
 31:   if (rank == 0) {
 32:     ja[0] = 1;
 33:     ja[1] = 4;
 34:     ja[2] = 0;
 35:     ja[3] = 2;
 36:     ja[4] = 5;
 37:     ja[5] = 1;
 38:     ja[6] = 3;
 39:     ja[7] = 6;
 40:     ja[8] = 2;
 41:     ja[9] = 7;
 42:     ia[0] = 0;
 43:     ia[1] = 2;
 44:     ia[2] = 5;
 45:     ia[3] = 8;
 46:     ia[4] = 10;
 47:   } else if (rank == 1) {
 48:     ja[0]  = 0;
 49:     ja[1]  = 5;
 50:     ja[2]  = 8;
 51:     ja[3]  = 1;
 52:     ja[4]  = 4;
 53:     ja[5]  = 6;
 54:     ja[6]  = 9;
 55:     ja[7]  = 2;
 56:     ja[8]  = 5;
 57:     ja[9]  = 7;
 58:     ja[10] = 10;
 59:     ja[11] = 3;
 60:     ja[12] = 6;
 61:     ja[13] = 11;
 62:     ia[0]  = 0;
 63:     ia[1]  = 3;
 64:     ia[2]  = 7;
 65:     ia[3]  = 11;
 66:     ia[4]  = 14;
 67:   } else if (rank == 2) {
 68:     ja[0]  = 4;
 69:     ja[1]  = 9;
 70:     ja[2]  = 12;
 71:     ja[3]  = 5;
 72:     ja[4]  = 8;
 73:     ja[5]  = 10;
 74:     ja[6]  = 13;
 75:     ja[7]  = 6;
 76:     ja[8]  = 9;
 77:     ja[9]  = 11;
 78:     ja[10] = 14;
 79:     ja[11] = 7;
 80:     ja[12] = 10;
 81:     ja[13] = 15;
 82:     ia[0]  = 0;
 83:     ia[1]  = 3;
 84:     ia[2]  = 7;
 85:     ia[3]  = 11;
 86:     ia[4]  = 14;
 87:   } else {
 88:     ja[0] = 8;
 89:     ja[1] = 13;
 90:     ja[2] = 9;
 91:     ja[3] = 12;
 92:     ja[4] = 14;
 93:     ja[5] = 10;
 94:     ja[6] = 13;
 95:     ja[7] = 15;
 96:     ja[8] = 11;
 97:     ja[9] = 14;
 98:     ia[0] = 0;
 99:     ia[1] = 2;
100:     ia[2] = 5;
101:     ia[3] = 8;
102:     ia[4] = 10;
103:   }
104:   PetscCall(MatCreateMPIAdj(comm, 4, 16, ia, ja, NULL, &A));
105:   PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
106:   /*
107:    Partition the graph of the matrix
108:   */
109:   PetscCall(MatPartitioningCreate(comm, &part));
110:   PetscCall(MatPartitioningSetAdjacency(part, A));
111:   PetscCall(MatPartitioningSetType(part, MATPARTITIONINGHIERARCH));
112:   PetscCall(MatPartitioningHierarchicalSetNcoarseparts(part, 2));
113:   PetscCall(MatPartitioningHierarchicalSetNfineparts(part, 2));
114:   PetscCall(MatPartitioningSetFromOptions(part));
115:   /* get new processor owner number of each vertex */
116:   PetscCall(MatPartitioningApply(part, &is));
117:   /* coarse parts */
118:   PetscCall(MatPartitioningHierarchicalGetCoarseparts(part, &coarseparts));
119:   PetscCall(ISView(coarseparts, PETSC_VIEWER_STDOUT_WORLD));
120:   /* fine parts */
121:   PetscCall(MatPartitioningHierarchicalGetFineparts(part, &fineparts));
122:   PetscCall(ISView(fineparts, PETSC_VIEWER_STDOUT_WORLD));
123:   /* partitioning */
124:   PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD));
125:   /* get new global number of each old global number */
126:   PetscCall(ISPartitioningToNumbering(is, &isn));
127:   PetscCall(ISView(isn, PETSC_VIEWER_STDOUT_WORLD));
128:   PetscCall(ISBuildTwoSided(is, NULL, &isrows));
129:   PetscCall(ISView(isrows, PETSC_VIEWER_STDOUT_WORLD));
130:   PetscCall(ISDestroy(&is));
131:   PetscCall(ISDestroy(&coarseparts));
132:   PetscCall(ISDestroy(&fineparts));
133:   PetscCall(ISDestroy(&isrows));
134:   PetscCall(ISDestroy(&isn));
135:   PetscCall(MatPartitioningDestroy(&part));
136:   /*
137:     Free work space.  All PETSc objects should be destroyed when they
138:     are no longer needed.
139:   */
140:   PetscCall(MatDestroy(&A));
141:   PetscCall(PetscFinalize());
142:   return 0;
143: }

145: /*TEST

147:    test:
148:       nsize: 4
149:       requires: parmetis
150:       TODO: tests cannot use ParMETIS because it produces different results on different machines

152: TEST*/