Sprout/sprout/math/atan2.hpp
2013-08-07 00:15:09 +09:00

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#ifndef SPROUT_MATH_ATAN2_HPP
#define SPROUT_MATH_ATAN2_HPP
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/limits.hpp>
#include <sprout/math/detail/config.hpp>
#include <sprout/math/detail/float_compute.hpp>
#include <sprout/math/constants.hpp>
#include <sprout/math/isnan.hpp>
#include <sprout/math/signbit.hpp>
#include <sprout/math/copysign.hpp>
#include <sprout/math/signbit.hpp>
#include <sprout/math/atan.hpp>
#include <sprout/type_traits/float_promote.hpp>
#include <sprout/type_traits/enabler_if.hpp>
namespace sprout {
namespace math {
namespace detail {
template<typename T>
inline SPROUT_CONSTEXPR T
atan2_impl(T y, T x) {
return x < 0 ? sprout::math::atan(y / x) + (
y < 0 ? -sprout::math::pi<T>()
: sprout::math::pi<T>()
)
: sprout::math::atan(y / x)
;
}
template<
typename FloatType,
typename sprout::enabler_if<std::is_floating_point<FloatType>::value>::type = sprout::enabler
>
inline SPROUT_CONSTEXPR FloatType
atan2(FloatType y, FloatType x) {
return sprout::math::isnan(y)
? sprout::math::isnan(x)
? sprout::math::signbit(y) && sprout::math::signbit(x) ? -sprout::numeric_limits<FloatType>::quiet_NaN()
: sprout::numeric_limits<FloatType>::quiet_NaN()
: y
: sprout::math::isnan(x) ? x
: x == -sprout::numeric_limits<FloatType>::infinity()
? y == sprout::numeric_limits<FloatType>::infinity() ? sprout::math::three_quarters_pi<FloatType>()
: y == -sprout::numeric_limits<FloatType>::infinity() ? -sprout::math::three_quarters_pi<FloatType>()
: sprout::math::copysign(sprout::math::pi<FloatType>(), y)
: x == sprout::numeric_limits<FloatType>::infinity()
? y == sprout::numeric_limits<FloatType>::infinity() ? sprout::math::quarter_pi<FloatType>()
: y == -sprout::numeric_limits<FloatType>::infinity() ? -sprout::math::quarter_pi<FloatType>()
: FloatType(0) * y
: y == sprout::numeric_limits<FloatType>::infinity() ? sprout::math::half_pi<FloatType>()
: y == -sprout::numeric_limits<FloatType>::infinity() ? -sprout::math::half_pi<FloatType>()
#if SPROUT_USE_BUILTIN_CMATH_FUNCTION
: std::atan2(y, x)
#else
: y == 0
? x < 0 ? sprout::math::copysign(sprout::math::pi<FloatType>(), y)
: x > 0 ? FloatType(0) * y
: sprout::math::signbit(x) ? sprout::math::copysign(sprout::math::pi<FloatType>(), y)
: FloatType(0) * y
: x == 0
? y < 0 ? -sprout::math::half_pi<FloatType>()
: sprout::math::half_pi<FloatType>()
: static_cast<FloatType>(
sprout::math::detail::atan2_impl(
static_cast<typename sprout::math::detail::float_compute<FloatType>::type>(y),
static_cast<typename sprout::math::detail::float_compute<FloatType>::type>(x)
)
)
#endif
;
}
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
atan2(ArithmeticType1 y, ArithmeticType2 x) {
typedef typename sprout::float_promote<ArithmeticType1, ArithmeticType2>::type type;
return sprout::math::detail::atan2(static_cast<type>(y), static_cast<type>(x));
}
} // namespace detail
//
// issue:
// [ !SPROUT_USE_BUILTIN_CMATH_FUNCTION ]
// atan2(<28>}0, -0) returns <20>}<7D><> .
// # returns <20>}0 . ( same as atan2(<28>}0, +0) )
// atan2(-0, x) returns -<2D><> for x < 0.
// # returns +<2B><> . ( same as atan2(+0, x) )
// atan2(-NaN, -NaN) returns -NaN .
// # returns +NaN . ( same as atan2(+NaN, +NaN) )
//
using sprout::math::detail::atan2;
} // namespace math
using sprout::math::atan2;
} // namespace sprout
#endif // #ifndef SPROUT_MATH_ATAN2_HPP