MPI_Group_size

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

C++ Syntax

#include <mpi.h>
int Group::Get_size() const

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. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI::Exception object.

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.