20 General utilities library [utilities]

20.16 Compile-time rational arithmetic [ratio]

20.16.1 In general [ratio.general]

Subclause [ratio] describes the ratio library.
It provides a class template ratio which exactly represents any finite rational number with a numerator and denominator representable by compile-time constants of type intmax_­t.
Throughout subclause [ratio], the names of template parameters are used to express type requirements.
If a template parameter is named R1 or R2, and the template argument is not a specialization of the ratio template, the program is ill-formed.