17.2.189. MPI_Group_incl

MPI_Group_incl - Produces a group by reordering an existing group and taking only listed members. Syntax C Syntax

#include <mpi.h>

int MPI_Group_incl(MPI_Group group, int n, const int ranks[],
    MPI_Group *newgroup) Fortran Syntax

! or the older form: INCLUDE 'mpif.h'

    INTEGER GROUP, N, RANKS(*), NEWGROUP, IERROR Fortran 2008 Syntax

USE mpi_f08

MPI_Group_incl(group, n, ranks, newgroup, ierror)
    TYPE(MPI_Group), INTENT(IN) :: group
    INTEGER, INTENT(IN) :: n, ranks(n)
    TYPE(MPI_Group), INTENT(OUT) :: newgroup
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror Input Parameters

  • group : Group (handle).

  • n : Number of elements in array ranks (and size of newgroup)(integer).

  • ranks : Ranks of processes in group to appear in newgroup (array of integers). Output Parameters

  • newgroup : New group derived from above, in the order defined by ranks (handle).

  • IERROR : Fortran only: Error status (integer). Description

The function MPI_Group_incl creates a group group_out that consists of the n processes in group with ranks rank[0], …, rank[n-1]; the process with rank i in group_out is the process with rank ranks[i] in group. Each of the n elements of ranks must be a valid rank in group and all elements must be distinct, or else the program is erroneous. If n = 0, then group_out is MPI_GROUP_EMPTY. This function can, for instance, be used to reorder the elements of a group. Note

This implementation does not currently check to ensure that there are no duplicates in the list of ranks. Errors

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.

Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.