1: static char help[] = "Example of using graph partitioning to partition a graph\n\n";

  3: #include <petscmat.h>

  5: int main(int argc, char **args)
  6: {
  7:   Mat             A;
  8:   MatPartitioning part;
  9:   IS              is;
 10:   PetscInt        r, N = 10, start, end, *vweights;
 11:   PetscBool       set_vweights = PETSC_FALSE, use_edge_weights = PETSC_FALSE;
 12:   PetscMPIInt     rank;
 13:   MPI_Comm        comm;

 15:   PetscFunctionBeginUser;
 16:   PetscCall(PetscInitialize(&argc, &args, NULL, help));
 17:   comm = PETSC_COMM_WORLD;
 18:   PetscCall(PetscOptionsGetInt(NULL, NULL, "-N", &N, NULL));
 19:   PetscCallMPI(MPI_Comm_rank(comm, &rank));
 20:   PetscCall(MatCreate(comm, &A));
 21:   PetscCall(MatSetSizes(A, PETSC_DECIDE, PETSC_DECIDE, N, N));
 22:   PetscCall(MatSetFromOptions(A));
 23:   PetscCall(MatSeqAIJSetPreallocation(A, 3, NULL));
 24:   PetscCall(MatMPIAIJSetPreallocation(A, 3, NULL, 2, NULL));
 25:   PetscCall(PetscOptionsGetBool(NULL, NULL, "-test_vertex_weights", &set_vweights, NULL));
 26:   PetscCall(PetscOptionsGetBool(NULL, NULL, "-test_use_edge_weights", &use_edge_weights, NULL));
 27:   /* Create a linear mesh */
 28:   PetscCall(MatGetOwnershipRange(A, &start, &end));
 29:   if (set_vweights) {
 30:     PetscCall(PetscMalloc1(end - start, &vweights));
 31:     for (r = start; r < end; ++r) vweights[r - start] = rank + 1;
 32:   }
 33:   for (r = start; r < end; ++r) {
 34:     if (r == 0) {
 35:       PetscInt    cols[2];
 36:       PetscScalar vals[2];

 38:       cols[0] = r;
 39:       cols[1] = r + 1;
 40:       vals[0] = 1.0;
 41:       vals[1] = use_edge_weights ? 2.0 : 1.0;

 43:       PetscCall(MatSetValues(A, 1, &r, 2, cols, vals, INSERT_VALUES));
 44:     } else if (r == N - 1) {
 45:       PetscInt    cols[2];
 46:       PetscScalar vals[2];

 48:       cols[0] = r - 1;
 49:       cols[1] = r;
 50:       vals[0] = use_edge_weights ? 3.0 : 1.0;
 51:       vals[1] = 1.0;

 53:       PetscCall(MatSetValues(A, 1, &r, 2, cols, vals, INSERT_VALUES));
 54:     } else {
 55:       PetscInt    cols[3];
 56:       PetscScalar vals[3];

 58:       cols[0] = r - 1;
 59:       cols[1] = r;
 60:       cols[2] = r + 1;
 61:       /* ADJ matrix needs to be symmetric */
 62:       vals[0] = use_edge_weights ? (cols[0] == 0 ? 2.0 : 5.0) : 1.0;
 63:       vals[1] = 1.0;
 64:       vals[2] = use_edge_weights ? (cols[2] == N - 1 ? 3.0 : 5.0) : 1.0;

 66:       PetscCall(MatSetValues(A, 1, &r, 3, cols, vals, INSERT_VALUES));
 67:     }
 68:   }
 69:   PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
 70:   PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));

 72:   PetscCall(MatPartitioningCreate(comm, &part));
 73:   PetscCall(MatPartitioningSetAdjacency(part, A));
 74:   if (set_vweights) PetscCall(MatPartitioningSetVertexWeights(part, vweights));
 75:   if (use_edge_weights) {
 76:     PetscCall(MatPartitioningSetUseEdgeWeights(part, use_edge_weights));

 78:     PetscCall(MatPartitioningGetUseEdgeWeights(part, &use_edge_weights));
 79:     PetscCheck(use_edge_weights, comm, PETSC_ERR_ARG_INCOMP, "use_edge_weights flag does not setup correctly ");
 80:   }
 81:   PetscCall(MatPartitioningSetFromOptions(part));
 82:   PetscCall(MatPartitioningApply(part, &is));
 83:   PetscCall(ISView(is, PETSC_VIEWER_STDOUT_WORLD));
 84:   PetscCall(ISDestroy(&is));
 85:   PetscCall(MatPartitioningDestroy(&part));

 87:   PetscCall(MatDestroy(&A));
 88:   PetscCall(PetscFinalize());
 89:   return 0;
 90: }

 92: /*TEST

 94:    test:
 95:       nsize: 3
 96:       requires: parmetis
 97:       args: -mat_partitioning_type parmetis

 99:    test:
100:       suffix: 2
101:       nsize: 3
102:       requires: ptscotch
103:       args: -mat_partitioning_type ptscotch

105:    test:
106:       suffix: 3
107:       nsize: 4
108:       requires: party
109:       args: -mat_partitioning_type party

111:    test:
112:       suffix: 4
113:       nsize: 3
114:       requires: chaco
115:       args: -mat_partitioning_type chaco

117:    test:
118:       suffix: 5
119:       nsize: 3
120:       requires: parmetis
121:       args: -mat_partitioning_type hierarch -mat_partitioning_hierarchical_nfineparts 3 -mat_partitioning_nparts 10 -N 100

123:    test:
124:       suffix: 6
125:       nsize: 3
126:       requires: parmetis
127:       args: -mat_partitioning_type hierarch -mat_partitioning_hierarchical_nfineparts 3 -mat_partitioning_nparts 10 -N 100 -test_vertex_weights 1 -mat_partitioning_use_edge_weights 1

129:    test:
130:       suffix: 7
131:       nsize: 2
132:       requires: parmetis
133:       args: -mat_partitioning_type hierarch -mat_partitioning_hierarchical_nfineparts 2 -mat_partitioning_nparts 10 -mat_partitioning_hierarchical_fineparttype hierarch -malloc_dump -N 100 -mat_partitioning_improve 1

135:    test:
136:       suffix: 8
137:       nsize: 2
138:       requires: parmetis
139:       args: -mat_partitioning_type parmetis -mat_partitioning_nparts 3 -test_use_edge_weights 1

141:    test:
142:       suffix: 9
143:       nsize: 2
144:       requires: ptscotch
145:       args: -mat_partitioning_type ptscotch -mat_partitioning_nparts 3 -test_use_edge_weights 1 -mat_partitioning_ptscotch_proc_weight 0

147: TEST*/