subroutine gather_tmp4(u_i)

  use m_parameters
  use m_io
  use m_work
  implicit none

  integer :: i,j,k
  real*8, dimension(nx,ny,nz_all) :: u_i

!======================================================================

  ! --- defining the size of whole array
  count = nx*ny*nz

  if (myid.ne.master) then
     id_to = master
     tag = myid
     call MPI_SEND(tmp4,count,MPI_REAL8,master,tag,MPI_COMM_TASK,mpi_err)
  else
     u_i(:,:,1:nz) = tmp4(:,:,:)

     do id_from=1,numprocs-1
        tag = id_from
        call MPI_RECV(tmp4,count,MPI_REAL8,id_from,tag,MPI_COMM_TASK,mpi_status,mpi_err)
        u_i(:,:,id_from*nz+1:id_from*nz+nz) = tmp4(:,:,:)
     end do
  end if

!======================================================================  

  return
end subroutine gather_tmp4