2: static char help[] = "Partition tiny grid using hierarchical partitioning and increase overlap using MatIncreaseOverlapSplit.\n\n";

  4: /*T
  5:    Concepts: partitioning
  6:    Processors: 4
  7: T*/

  9: /*
 10:   Include "petscmat.h" so that we can use matrices.  Note that this file
 11:   automatically includes:
 12:      petscsys.h       - base PETSc routines   petscvec.h - vectors
 13:      petscmat.h - matrices
 14:      petscis.h     - index sets
 15:      petscviewer.h - viewers
 16: */
 17: #include <petscmat.h>

 21: int main(int argc,char **args)
 22: {
 23:   Mat             A,B;
 24:   PetscErrorCode  ierr;
 25:   PetscMPIInt     rank,size,membershipKey;
 26:   PetscInt        *ia,*ja,*indices_sc,isrows_localsize;
 27:   const PetscInt  *indices;
 28:   MatPartitioning part;
 29:   IS              is,isrows,isrows_sc;
 30:   IS              coarseparts,fineparts;
 31:   MPI_Comm        comm,scomm;

 33:   PetscInitialize(&argc,&args,(char*)0,help);
 34:   comm = PETSC_COMM_WORLD;
 35:   MPI_Comm_size(comm,&size);
 36:   if (size != 4) SETERRQ(comm,1,"Must run with 4 processors \n");
 37:   MPI_Comm_rank(comm,&rank);
 38:   /*set a small matrix */
 39:   PetscMalloc1(5,&ia);
 40:   PetscMalloc1(16,&ja);
 41:   if (!rank) {
 42:     ja[0] = 1; ja[1] = 4; ja[2] = 0; ja[3] = 2; ja[4] = 5; ja[5] = 1; ja[6] = 3; ja[7] = 6;
 43:     ja[8] = 2; ja[9] = 7;
 44:     ia[0] = 0; ia[1] = 2; ia[2] = 5; ia[3] = 8; ia[4] = 10;
 45:     membershipKey = 0;
 46:   } else if (rank == 1) {
 47:     ja[0] = 0; ja[1] = 5; ja[2] = 8; ja[3] = 1; ja[4] = 4; ja[5] = 6; ja[6] = 9; ja[7] = 2;
 48:     ja[8] = 5; ja[9] = 7; ja[10] = 10; ja[11] = 3; ja[12] = 6; ja[13] = 11;
 49:     ia[0] = 0; ia[1] = 3; ia[2] = 7; ia[3] = 11; ia[4] = 14;
 50:     membershipKey = 0;
 51:   } else if (rank == 2) {
 52:     ja[0] = 4; ja[1] = 9; ja[2] = 12; ja[3] = 5; ja[4] = 8; ja[5] = 10; ja[6] = 13; ja[7] = 6;
 53:     ja[8] = 9; ja[9] = 11; ja[10] = 14; ja[11] = 7; ja[12] = 10; ja[13] = 15;
 54:     ia[0] = 0; ia[1] = 3; ia[2] = 7; ia[3] = 11; ia[4] = 14;
 55:     membershipKey = 1;
 56:   } else {
 57:     ja[0] = 8; ja[1] = 13; ja[2] = 9; ja[3] = 12; ja[4] = 14; ja[5] = 10; ja[6] = 13; ja[7] = 15;
 58:     ja[8] = 11; ja[9] = 14;
 59:     ia[0] = 0; ia[1] = 2; ia[2] = 5; ia[3] = 8; ia[4] = 10;
 60:     membershipKey = 1;
 61:   }
 62:   MatCreateMPIAdj(comm,4,16,ia,ja,NULL,&A);
 63:   MatView(A,PETSC_VIEWER_STDOUT_WORLD);
 64:   /*
 65:    Partition the graph of the matrix
 66:   */
 67:   MatPartitioningCreate(comm,&part);
 68:   MatPartitioningSetAdjacency(part,A);
 69:   MatPartitioningSetType(part,MATPARTITIONINGHIERARCH);
 70:   MatPartitioningHierarchicalSetNcoarseparts(part,2);
 71:   MatPartitioningHierarchicalSetNfineparts(part,2);
 72:   MatPartitioningSetFromOptions(part);
 73:   /* get new processor owner number of each vertex */
 74:   MatPartitioningApply(part,&is);
 75:   /* coarse parts */
 76:   MatPartitioningHierarchicalGetCoarseparts(part,&coarseparts);
 77:   ISView(coarseparts,PETSC_VIEWER_STDOUT_WORLD);
 78:   /* fine parts */
 79:   MatPartitioningHierarchicalGetFineparts(part,&fineparts);
 80:   ISView(fineparts,PETSC_VIEWER_STDOUT_WORLD);
 81:   /* partitioning */
 82:   ISView(is,PETSC_VIEWER_STDOUT_WORLD);
 83:   /* compute coming rows */
 84:   ISBuildTwoSided(is,NULL,&isrows);
 85:   ISView(isrows,PETSC_VIEWER_STDOUT_WORLD);
 86:   /*create a sub-communicator */
 87:   MPI_Comm_split(comm, membershipKey,rank,&scomm);
 88:   ISGetLocalSize(isrows,&isrows_localsize);
 89:   PetscCalloc1(isrows_localsize,&indices_sc);
 90:   ISGetIndices(isrows,&indices);
 91:   PetscMemcpy(indices_sc,indices,sizeof(PetscInt)*isrows_localsize);
 92:   ISRestoreIndices(isrows,&indices);
 93:   ISDestroy(&is);
 94:   ISDestroy(&coarseparts);
 95:   ISDestroy(&fineparts);
 96:   ISDestroy(&isrows);
 97:   MatPartitioningDestroy(&part);
 98:   /*create a sub-IS on the sub communicator  */
 99:   ISCreateGeneral(scomm,isrows_localsize,indices_sc,PETSC_OWN_POINTER,&isrows_sc);
100:   MatConvert(A,MATMPIAIJ,MAT_INITIAL_MATRIX,&B);
101: #if 1
102:   MatView(B,PETSC_VIEWER_STDOUT_WORLD);
103: #endif
104:   /*increase overlap */
105:   MatIncreaseOverlapSplit(B,1,&isrows_sc,1);
106:   ISView(isrows_sc,PETSC_NULL);
107:   ISDestroy(&isrows_sc);
108:   /*
109:     Free work space.  All PETSc objects should be destroyed when they
110:     are no longer needed.
111:   */
112:   MatDestroy(&A);
113:   MatDestroy(&B);
114:   PetscFinalize();
115:   return 0;
116: }