Sprout/sprout/math/pow.hpp
2012-05-04 23:23:39 +09:00

89 lines
2.5 KiB
C++

#ifndef SPROUT_MATH_POW_HPP
#define SPROUT_MATH_POW_HPP
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/math/exp.hpp>
#include <sprout/math/log.hpp>
#include <sprout/math/constants.hpp>
#include <sprout/utility/enabler_if.hpp>
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
# include <cmath>
#endif
namespace sprout {
namespace math {
namespace detail {
template<typename X, typename Y, typename Enable = void>
struct pow_promoted {};
template<typename X, typename Y>
struct pow_promoted<
X,
Y,
typename std::enable_if<
std::is_arithmetic<X>::value && std::is_arithmetic<Y>::value
&& (std::is_same<X, long double>::value || std::is_same<Y, long double>::value)
>::type
> {
public:
typedef long double type;
};
template<typename X, typename Y>
struct pow_promoted<
X,
Y,
typename std::enable_if<
std::is_arithmetic<X>::value && std::is_arithmetic<Y>::value
&& !(std::is_same<X, long double>::value || std::is_same<Y, long double>::value)
>::type
> {
public:
typedef double type;
};
} // namespace detail
//
// pow_promoted
//
template<typename X, typename Y>
struct pow_promoted
: public sprout::math::detail::pow_promoted<
typename std::remove_cv<X>::type,
typename std::remove_cv<Y>::type
>
{};
namespace detail {
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
pow(FloatType x, FloatType y) {
return sprout::math::detail::exp(y * sprout::math::detail::log(x));
}
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::math::pow_promoted<ArithmeticType1, ArithmeticType2>::type
pow(ArithmeticType1 x, ArithmeticType2 y) {
typedef typename sprout::math::pow_promoted<ArithmeticType1, ArithmeticType2>::type type;
return sprout::math::detail::pow(static_cast<type>(x), static_cast<type>(y));
}
} // namespace detail
# if SPROUT_USE_BUILTIN_CMATH_FUNCTION
using std::pow;
# else
using sprout::math::detail::pow;
# endif
} // namespace math
using sprout::math::pow;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_POW_HPP