function dcdatetime_min_ff(diff1, diff2) result(result)
    !
    ! 2 つの引数の日時差を比較し, より小さい方を返します. 
    !
    use dc_date_generic, only: operator(<)
    use dc_date_types, only: DC_DATETIME, DC_DIFFTIME
    use dc_date_internal, only: dcdate_nondimcheck
    implicit none
    type(DC_DIFFTIME):: result
    type(DC_DIFFTIME), intent(in):: diff1, diff2
  continue
    if ( diff1 < diff2 ) then
      result = diff1
    else
      result = diff2
    end if
    call dcdate_nondimcheck('dc_date#min', diff1, diff2, result)
  end function dcdatetime_min_ff

  function dcdatetime_min_tt(time1, time2) result(result)
    !
    ! 2 つの引数の日時を比較し, より日時が遅れている方を返します. 
    !
    use dc_date_generic, only: operator(<)
    use dc_date_types, only: DC_DATETIME, DC_DIFFTIME
    implicit none
    type(DC_DATETIME):: result
    type(DC_DATETIME), intent(in):: time1, time2
  continue
    if ( time1 < time2 ) then
      result = time1
    else
      result = time2
    end if
  end function dcdatetime_min_tt