Sprout/sprout/math/log_a.hpp
2017-07-29 14:20:01 +09:00

64 lines
2.3 KiB
C++

/*=============================================================================
Copyright (c) 2011-2017 Bolero MURAKAMI
https://github.com/bolero-MURAKAMI/Sprout
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#ifndef SPROUT_MATH_LOG_A_HPP
#define SPROUT_MATH_LOG_A_HPP
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/detail/float_compute.hpp>
#include <sprout/math/constants.hpp>
#include <sprout/math/log.hpp>
#include <sprout/type_traits/enabler_if.hpp>
#include <sprout/type_traits/float_promote.hpp>
namespace sprout {
namespace math {
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
log_a_impl(T x, T y) {
return x == 2 ? sprout::math::log(y) / sprout::math::ln_two<T>()
: x == 10 ? sprout::math::log(y) / sprout::math::ln_ten<T>()
: sprout::math::log(y) / sprout::math::log(x)
;
}
} // namespace detail
//
// log_a
//
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
log_a(FloatType x, FloatType y) {
return static_cast<FloatType>(sprout::math::detail::log_a_impl(
static_cast<typename sprout::math::detail::float_compute<FloatType>::type>(x),
static_cast<typename sprout::math::detail::float_compute<FloatType>::type>(y)
));
}
template<
typename ArithmeticType1,
typename ArithmeticType2,
typename sprout::enabler_if<
std::is_arithmetic<ArithmeticType1>::value && std::is_arithmetic<ArithmeticType2>::value
>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type
log_a(ArithmeticType1 x, ArithmeticType2 y) {
typedef typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type type;
return sprout::math::log_a(static_cast<type>(x), static_cast<type>(y));
}
} // namespace math
using sprout::math::log_a;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_LOG_A_HPP