23 General utilities library [utilities]

23.16 Compile-time rational arithmetic [ratio]

23.16.5 Comparison of ratios [ratio.comparison]

template <class R1, class R2> struct ratio_equal : bool_constant<R1::num == R2::num && R1::den == R2::den> { }; template <class R1, class R2> struct ratio_not_equal : bool_constant<!ratio_equal_v<R1, R2>> { }; template <class R1, class R2> struct ratio_less : bool_constant<see below> { };
If R1​::​num × R2​::​den is less than R2​::​num × R1​::​den, ratio_­less<R1, R2> shall be derived from bool_­constant<true>; otherwise it shall be derived from bool_­constant<false>.
Implementations may use other algorithms to compute this relationship to avoid overflow.
If overflow occurs, the program is ill-formed.
template <class R1, class R2> struct ratio_less_equal : bool_constant<!ratio_less_v<R2, R1>> { }; template <class R1, class R2> struct ratio_greater : bool_constant<ratio_less_v<R2, R1>> { }; template <class R1, class R2> struct ratio_greater_equal : bool_constant<!ratio_less_v<R1, R2>> { };