1 /* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- */
3 * (C) 2011 by Argonne National Laboratory.
4 * See COPYRIGHT in top-level directory.
7 #include "mpitestconf.h"
13 int main(int argc, char *argv[])
15 int size, rank, i, *excl;
16 MPI_Group world_group, even_group;
19 MPI_Init(&argc, &argv);
21 MPI_Comm_size(MPI_COMM_WORLD, &size);
22 MPI_Comm_rank(MPI_COMM_WORLD, &rank);
25 fprintf(stderr, "this program requires a multiple of 2 number of processes\n");
26 MPI_Abort(MPI_COMM_WORLD, 1);
29 excl = malloc((size / 2) * sizeof(int));
32 /* exclude the odd ranks */
33 for (i = 0; i < size / 2; i++)
34 excl[i] = (2 * i) + 1;
36 /* Create some groups */
37 MPI_Comm_group(MPI_COMM_WORLD, &world_group);
38 MPI_Group_excl(world_group, size / 2, excl, &even_group);
39 MPI_Group_free(&world_group);
42 /* Even processes create a group for themselves */
43 MPI_Comm_create_group(MPI_COMM_WORLD, even_group, 0, &even_comm);
44 MPI_Barrier(even_comm);
45 MPI_Comm_free(&even_comm);
48 MPI_Group_free(&even_group);
49 MPI_Barrier(MPI_COMM_WORLD);
52 printf(" No errors\n");