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add math functions: logb, ilogb

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bolero-MURAKAMI 2013-02-07 18:14:50 +09:00
parent 4b3d4e82d7
commit d05b597e80
13 changed files with 218 additions and 11 deletions
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102
sprout/math/logb.hpp Normal file
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#ifndef SPROUT_MATH_LOGB_HPP
#define SPROUT_MATH_LOGB_HPP
#include <climits>
#include <cfloat>
#include <cstdint>
#include <type_traits>
#include <stdexcept>
#include <sprout/config.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/detail/pow.hpp>
#include <sprout/math/log_a.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
logb_impl_2_neg_lo(T x, T x0, T base, T exp) {
return base < 1 ? sprout::math::detail::logb_impl_2_neg_lo(x, x0 * FLT_RADIX, x / (x0 / FLT_RADIX), exp - 1)
: exp
;
}
template<typename T>
inline SPROUT_CONSTEXPR T
logb_impl_2_neg_hi(T x, T x0, T base, T exp) {
return !(base < FLT_RADIX) ? sprout::math::detail::logb_impl_2_neg_hi(x, x0 / FLT_RADIX, x / (x0 * FLT_RADIX), exp + 1)
: exp
;
}
template<typename T>
inline SPROUT_CONSTEXPR T
logb_impl_2_pos_lo(T x, T x0, T base, T exp) {
return base < 1 ? sprout::math::detail::logb_impl_2_pos_lo(x, x0 * FLT_RADIX, x / (x0 / FLT_RADIX), exp + 1)
: exp
;
}
template<typename T>
inline SPROUT_CONSTEXPR T
logb_impl_2_pos_hi(T x, T x0, T base, T exp) {
return !(base < FLT_RADIX) ? sprout::math::detail::logb_impl_2_pos_hi(x, x0 / FLT_RADIX, x / (x0 * FLT_RADIX), exp - 1)
: exp
;
}
template<typename T>
inline SPROUT_CONSTEXPR T
logb_impl_2(T x, T x0, T base, T exp) {
return exp < 0
? base < 1 ? sprout::math::detail::logb_impl_2_neg_lo(x, x0 * FLT_RADIX, x / (x0 / FLT_RADIX), exp - 1)
: !(base < FLT_RADIX) ? sprout::math::detail::logb_impl_2_neg_hi(x, x0 / FLT_RADIX, x / (x0 * FLT_RADIX), exp + 1)
: exp
: base < 1 ? sprout::math::detail::logb_impl_2_pos_lo(x, x0 * FLT_RADIX, x / (x0 / FLT_RADIX), exp + 1)
: !(base < FLT_RADIX) ? sprout::math::detail::logb_impl_2_pos_hi(x, x0 / FLT_RADIX, x / (x0 * FLT_RADIX), exp - 1)
: exp
;
}
template<typename T>
inline SPROUT_CONSTEXPR T
logb_impl_1(T x, T x0, T exp) {
return sprout::math::detail::logb_impl_2(x, x0, x / x0, exp);
}
template<typename T>
inline SPROUT_CONSTEXPR T
logb_impl(T x, T exp) {
return std::numeric_limits<std::intmax_t>::max() < exp || std::numeric_limits<std::intmax_t>::min() > exp
? SPROUT_MATH_THROW_LARGE_FLOAT_ROUNDING(std::domain_error("trunc: large float rounding."), exp)
: sprout::math::detail::logb_impl_1(
x, sprout::detail::pow_n(T(FLT_RADIX), static_cast<std::intmax_t>(exp)),
static_cast<T>(static_cast<std::intmax_t>(exp))
)
;
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
logb(FloatType x) {
return x < 0 ? sprout::math::detail::logb_impl(-x, sprout::math::trunc(sprout::math::log_a(FloatType(FLT_RADIX), -x)))
: sprout::math::detail::logb_impl(x, sprout::math::trunc(sprout::math::log_a(FloatType(FLT_RADIX), x)))
;
}
template<
typename IntType,
typename sprout::enabler_if<std::is_integral<IntType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR double
logb(IntType x) {
return sprout::math::detail::logb(static_cast<double>(x));
}
} // namespace detail
using NS_SPROUT_MATH_DETAIL::logb;
} // namespace math
using sprout::math::logb;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_LOGB_HPP