nb_sum_allreduce_sub_complex_2array Subroutine

  subroutine nb_sum_allreduce_sub_complex_2array (z,sub_comm,request)
    implicit none
    complex, dimension (:,:), intent (in out) :: z
    integer, intent(in) :: sub_comm
    integer, intent(out) :: request
# ifdef MPI3
    integer :: ierror
!$OMP MASTER
    call time_message(.false., time_mp_collectives, ' MPI Collectives')
!$OMP END MASTER
    call mpi_iallreduce &
         (MPI_IN_PLACE, z, size(z), mpicmplx, MPI_SUM, sub_comm, request, ierror)
!$OMP MASTER
    call time_message(.false., time_mp_collectives, ' MPI Collectives')
!$OMP END MASTER
# else
    call sum_allreduce_sub(z, sub_comm)
    request = mp_request_null
# endif
  end subroutine nb_sum_allreduce_sub_complex_2array