Actual source code: ex80.c

  1: /*$Id: ex80.c,v 1.10 2001/04/10 19:35:44 bsmith Exp $*/

  3: static char help[] = "Partition tiny grid.\n\n";

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

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

 22: int main(int argc,char **args)
 23: {
 24:   Mat             A;
 25:   int             ierr,rank,*ia,*ja,size;
 26:   MatPartitioning part;
 27:   IS              is,isn;

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

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

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

 57:   /*
 58:        Partition the graph of the matrix 
 59:   */
 60:   MatPartitioningCreate(PETSC_COMM_WORLD,&part);
 61:   MatPartitioningSetAdjacency(part,A);
 62:   MatPartitioningSetFromOptions(part);
 63:   /* get new processor owner number of each vertex */
 64:   MatPartitioningApply(part,&is);
 65:   /* get new global number of each old global number */
 66:   ISPartitioningToNumbering(is,&isn);
 67:   ISView(isn,PETSC_VIEWER_STDOUT_WORLD);
 68:   ISDestroy(is);

 70:   ISDestroy(isn);
 71:   MatPartitioningDestroy(part);

 73:   /*
 74:        Free work space.  All PETSc objects should be destroyed when they
 75:        are no longer needed.
 76:   */
 77:   MatDestroy(A);


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