receive_real_4d_array Subroutine

  subroutine receive_real_4d_array (a, src, tag)
    implicit none
    real, dimension (:,:,:,:), intent (out) :: a
    integer, intent (in) :: src
    integer, intent (in), optional :: tag
# ifdef MPI
    integer :: ierror
    integer :: tagp
    integer, dimension (mp_status_size) :: status
    tagp = 0
    if (present(tag)) tagp = tag
    call mpi_recv (a, size(a), mpireal, src, tagp, mp_comm, &
        status, ierror)
# else
    call mp_abort ("receive")
    UNUSED_DUMMY(src); UNUSED_DUMMY(tag)
    a = 0
# endif
  end subroutine receive_real_4d_array