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MPI_Group_size(3) man page (version 1.8)

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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


INCLUDE ’mpif.h’
MPI_GROUP_SIZE(GROUP, SIZE, IERROR)
    INTEGER    GROUP, SIZE, 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.


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