56 lines
1.5 KiB
Markdown
56 lines
1.5 KiB
Markdown
[ratio.comparison]
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# 21 Metaprogramming library [[meta]](./#meta)
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## 21.5 Compile-time rational arithmetic [[ratio]](ratio#comparison)
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### 21.5.5 Comparison of ratios [ratio.comparison]
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[ð](#lib:ratio_equal)
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`template<class R1, class R2>
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struct ratio_equal : bool_constant<R1::num == R2::num && R1::den == R2::den> { };
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`
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[ð](#lib:ratio_not_equal)
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`template<class R1, class R2>
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struct ratio_not_equal : bool_constant<!ratio_equal_v<R1, R2>> { };
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`
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[ð](#lib:ratio_less)
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`template<class R1, class R2>
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struct ratio_less : bool_constant<see below> { };
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`
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/meta.tex#L7242)
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If R1::num × R2::den is less than R2::num × R1::den,ratio_less<R1, R2> shall be
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derived from bool_constant<true>; otherwise it shall be derived frombool_constant<false>[.](#1.sentence-1)
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Implementations may use other algorithms to
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compute this relationship to avoid overflow[.](#1.sentence-2)
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If overflow occurs, the program is ill-formed[.](#1.sentence-3)
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[ð](#lib:ratio_less_equal)
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`template<class R1, class R2>
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struct ratio_less_equal : bool_constant<!ratio_less_v<R2, R1>> { };
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`
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[ð](#lib:ratio_greater)
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`template<class R1, class R2>
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struct ratio_greater : bool_constant<ratio_less_v<R2, R1>> { };
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`
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[ð](#lib:ratio_greater_equal)
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`template<class R1, class R2>
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struct ratio_greater_equal : bool_constant<!ratio_less_v<R1, R2>> { };
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`
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