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dealing with exponent during sqrt

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fixes #58
This commit is contained in:
Oliver Schönrock
2020-02-15 14:08:27 +00:00
committed by Mateusz Pusz
parent fc62c04a46
commit 291d3d1eb7
2 changed files with 17 additions and 4 deletions
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17
src/include/units/ratio.h
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@@ -200,10 +200,23 @@ constexpr std::intmax_t sqrt_impl(std::intmax_t v, std::intmax_t l, std::intmax_
static constexpr std::intmax_t sqrt_impl(std::intmax_t v) { return sqrt_impl(v, 1, v); }
template<Ratio R>
constexpr std::tuple<std::intmax_t, std::intmax_t, std::intmax_t> make_exp_even()
{
if constexpr (R::exp % 2 == 0)
return {R::num, R::den, R::exp}; // already even (incl zero)
// safely make exp even, so it can be divided by 2 for square root
if constexpr (R::exp > 0)
return {R::num * 10, R::den, R::exp - 1};
else
return {R::num, R::den * 10, R::exp + 1};
}
template<typename R>
struct ratio_sqrt_impl {
// TODO(#58) Provide sqrt on exp
using type = ratio<detail::sqrt_impl(R::num), detail::sqrt_impl(R::den) /* , exp */>;
constexpr static auto even = detail::make_exp_even<R>();
using type = ratio<detail::sqrt_impl(std::get<0>(even)), detail::sqrt_impl(std::get<1>(even)), std::get<2>(even) / 2>;
};
template<std::intmax_t Den>

4
test/unit_test/static/math_test.cpp
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@@ -36,7 +36,7 @@ namespace {
static_assert(std::is_same_v<decltype(pow<2>(2km)), decltype(4km2)>);
static_assert(std::is_same_v<decltype(pow<2>(2ft)), decltype(4ft2)>);
static_assert(std::is_same_v<decltype(sqrt(4m2)), decltype(2m)>);
// static_assert(std::is_same_v<decltype(sqrt(4km2)), decltype(2km)>);
// static_assert(std::is_same_v<decltype(sqrt(4ft2)), decltype(2ft)>);
static_assert(std::is_same_v<decltype(sqrt(4km2)), decltype(2km)>);
static_assert(std::is_same_v<decltype(sqrt(4ft2)), decltype(2ft)>);
} // namespace