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MPI_Group_size(3) man page (version 5.0.0rc2)

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Name

MPI_Group_size - Returns the size of a group.

Syntax

C Syntax


#include <mpi.h>
int MPI_Group_size(MPI_Group group, int *size)

Fortran Syntax


USE MPI
! or the older form: INCLUDE ’mpif.h’
MPI_GROUP_SIZE(GROUP, SIZE, IERROR)
    INTEGER    GROUP, SIZE, IERROR

Fortran 2008 Syntax


USE mpi_f08
MPI_Group_size(group, size, ierror)
    TYPE(MPI_Group), INTENT(IN) :: group
    INTEGER, INTENT(OUT) :: size
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror

Input Parameters

group
Group (handle).

Output Parameters

size
Number of processes in the group (integer).
IERROR
Fortran only: Error status (integer).

Description

MPI_Group_size returns in size the number of processes in the group. Thus, if group = MPI_GROUP_EMPTY, then the call will return size = 0. On the other hand, a call with group = MPI_GROUP_NULL is erroneous.

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.


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