get_left_connection Subroutine

  subroutine get_left_connection (iglo, iglo_left, iproc_left)
    use gs2_layouts, only: g_lo, proc_id, idx
    use gs2_layouts, only: ik_idx, it_idx, il_idx, ie_idx, is_idx
    implicit none
    integer, intent (in) :: iglo
    integer, intent (out) :: iglo_left, iproc_left
    integer :: ik, it, il, ie, is

    ik = ik_idx(g_lo,iglo)
    it = it_idx(g_lo,iglo)
    
    if (itleft(it, ik) < 0) then
       iglo_left = -1
       iproc_left = -1
       return
    end if

    il = il_idx(g_lo,iglo)
    ie = ie_idx(g_lo,iglo)
    is = is_idx(g_lo,iglo)

    iglo_left = idx(g_lo,ik,itleft(it, ik),il,ie,is)
    iproc_left = proc_id(g_lo,iglo_left)
  end subroutine get_left_connection