sum_allreduce_real_array Subroutine

  subroutine sum_allreduce_real_array (a)
    implicit none
    real, dimension (:), intent (in out) :: a
# ifdef MPI
    integer :: ierror
!$OMP MASTER
    call time_message(.false., time_mp_collectives, ' MPI Collectives')
!$OMP END MASTER
    call mpi_allreduce &
         (MPI_IN_PLACE, a, size(a), mpireal, MPI_SUM, mp_comm, ierror)
!$OMP MASTER
    call time_message(.false., time_mp_collectives, ' MPI Collectives')
!$OMP END MASTER
# else
    UNUSED_DUMMY(a)
# endif
  end subroutine sum_allreduce_real_array