/* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */

/*

 *

 *  (C) 2003 by Argonne National Laboratory.

 *      See COPYRIGHT in top-level directory.

 */

#include "mpi.h"

#include <stdio.h>

#include <stdlib.h>

#include "mpitest.h"

/*

static char MTEST_Descrip[] = "Test comm split";

*/

int main(int argc, char *argv[])

{

    int errs = 0;

    int rank, size, color, srank;

    MPI_Comm comm, scomm;

    MTest_Init(&argc, &argv);

    MPI_Comm_dup(MPI_COMM_WORLD, &comm);

    MPI_Comm_rank(comm, &rank;;

    MPI_Comm_size(comm, &size);

    if (size < 4) {

        fprintf(stderr, "This test requires at least four processes.");

        MPI_Abort(MPI_COMM_WORLD, 1);

    }

    color = MPI_UNDEFINED;

    if (rank < 2)

        color = 1;

    MPI_Comm_split(comm, color, size - rank, &scomm);

    if (rank < 2) {

        /* Check that the ranks are ordered correctly */

        MPI_Comm_rank(scomm, &srank);

        if (srank != 1 - rank) {

            errs++;

        }

        MPI_Comm_free(&scomm);

    }

    else {

        if (scomm != MPI_COMM_NULL) {

            errs++;

        }

    }

    MPI_Comm_free(&comm);

    MTest_Finalize(errs);

    MPI_Finalize();

    return 0;

}