Actual source code: ex80.c
petsc-3.4.2 2013-07-02

      2: static char help[] = "Partition tiny grid.\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;
     24:   PetscErrorCode  ierr;
     25:   PetscMPIInt     rank,size;
     26:   PetscInt        *ia,*ja;
     27:   MatPartitioning part;
     28:   IS              is,isn;

     30:   PetscInitialize(&argc,&args,(char*)0,help);
     31:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
     32:   if (size != 4) SETERRQ(PETSC_COMM_WORLD,1,"Must run with 4 processors");
     33:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);

     35:   PetscMalloc(5*sizeof(PetscInt),&ia);
     36:   PetscMalloc(16*sizeof(PetscInt),&ja);
     37:   if (!rank) {
     38:     ja[0] = 1; ja[1] = 4; ja[2] = 0; ja[3] = 2; ja[4] = 5; ja[5] = 1; ja[6] = 3; ja[7] = 6;
     39:     ja[8] = 2; ja[9] = 7;
     40:     ia[0] = 0; ia[1] = 2; ia[2] = 5; ia[3] = 8; ia[4] = 10;
     41:   } else if (rank == 1) {
     42:     ja[0] = 0; ja[1] = 5; ja[2] = 8; ja[3] = 1; ja[4] = 4; ja[5] = 6; ja[6] = 9; ja[7] = 2;
     43:     ja[8] = 5; ja[9] = 7; ja[10] = 10; ja[11] = 3; ja[12] = 6; ja[13] = 11;
     44:     ia[0] = 0; ia[1] = 3; ia[2] = 7; ia[3] = 11; ia[4] = 14;
     45:   } else if (rank == 2) {
     46:     ja[0] = 4; ja[1] = 9; ja[2] = 12; ja[3] = 5; ja[4] = 8; ja[5] = 10; ja[6] = 13; ja[7] = 6;
     47:     ja[8] = 9; ja[9] = 11; ja[10] = 14; ja[11] = 7; ja[12] = 10; ja[13] = 15;
     48:     ia[0] = 0; ia[1] = 3; ia[2] = 7; ia[3] = 11; ia[4] = 14;
     49:   } else {
     50:     ja[0] = 8; ja[1] = 13; ja[2] = 9; ja[3] = 12; ja[4] = 14; ja[5] = 10; ja[6] = 13; ja[7] = 15;
     51:     ja[8] = 11; ja[9] = 14;
     52:     ia[0] = 0; ia[1] = 2; ia[2] = 5; ia[3] = 8; ia[4] = 10;
     53:   }

     55:   MatCreateMPIAdj(PETSC_COMM_WORLD,4,16,ia,ja,NULL,&A);
     56:   MatView(A,PETSC_VIEWER_STDOUT_WORLD);

     58:   /*
     59:        Partition the graph of the matrix
     60:   */
     61:   MatPartitioningCreate(PETSC_COMM_WORLD,&part);
     62:   MatPartitioningSetAdjacency(part,A);
     63:   MatPartitioningSetFromOptions(part);
     64:   /* get new processor owner number of each vertex */
     65:   MatPartitioningApply(part,&is);
     66:   /* get new global number of each old global number */
     67:   ISPartitioningToNumbering(is,&isn);
     68:   ISView(isn,PETSC_VIEWER_STDOUT_WORLD);
     69:   ISDestroy(&is);

     71:   ISDestroy(&isn);
     72:   MatPartitioningDestroy(&part);

     74:   /*
     75:        Free work space.  All PETSc objects should be destroyed when they
     76:        are no longer needed.
     77:   */
     78:   MatDestroy(&A);

     81:   PetscFinalize();
     82:   return 0;
     83: }