2: static char help[] = "Tests MatMeshToDual()\n\n";

  4: /*T
  5:    Concepts: Mat^mesh partitioning
  6:    Processors: n
  7: T*/

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

 20: int main(int argc,char **args)
 21: {
 22:   Mat             mesh,dual;
 23:   PetscErrorCode  ierr;
 24:   PetscInt        Nvertices = 6;       /* total number of vertices */
 25:   PetscInt        ncells    = 2;       /* number cells on this process */
 26:   PetscInt        *ii,*jj;
 27:   PetscMPIInt     size,rank;
 28:   MatPartitioning part;
 29:   IS              is;

 31:   PetscInitialize(&argc,&args,(char*)0,help);
 32:   MPI_Comm_size(MPI_COMM_WORLD,&size);
 33:   if (size != 2) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP,"This example is for exactly two processes");
 34:   MPI_Comm_rank(MPI_COMM_WORLD,&rank);

 36:   PetscMalloc1(3,&ii);
 37:   PetscMalloc1(6,&jj);
 38:   ii[0] = 0; ii[1] = 3; ii[2] = 6;
 39:   if (!rank) {
 40:     jj[0] = 0; jj[1] = 1; jj[2] = 2; jj[3] = 1; jj[4] = 2; jj[5] = 3;
 41:   } else {
 42:     jj[0] = 1; jj[1] = 4; jj[2] = 5; jj[3] = 1; jj[4] = 3; jj[5] = 5;
 43:   }
 44:   MatCreateMPIAdj(MPI_COMM_WORLD,ncells,Nvertices,ii,jj,NULL,&mesh);
 45:   MatMeshToCellGraph(mesh,2,&dual);
 46:   MatView(dual,PETSC_VIEWER_STDOUT_WORLD);

 48:   MatPartitioningCreate(MPI_COMM_WORLD,&part);
 49:   MatPartitioningSetAdjacency(part,dual);
 50:   MatPartitioningSetFromOptions(part);
 51:   MatPartitioningApply(part,&is);
 52:   ISView(is,PETSC_VIEWER_STDOUT_WORLD);
 53:   ISDestroy(&is);
 54:   MatPartitioningDestroy(&part);

 56:   MatDestroy(&mesh);
 57:   MatDestroy(&dual);
 58:   PetscFinalize();
 59:   return 0;
 60: }