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.