fmax.hpp
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// (C) Copyright Matt Borland 2022.
// Use, modification and distribution are subject to 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 BOOST_MATH_CCMATH_FMAX_HPP
#define BOOST_MATH_CCMATH_FMAX_HPP
#include <cmath>
#include <limits>
#include <type_traits>
#include <boost/math/tools/is_constant_evaluated.hpp>
#include <boost/math/ccmath/isnan.hpp>
namespace boost::math::ccmath {
namespace detail {
template <typename T>
inline constexpr T fmax_impl(const T x, const T y) noexcept
{
if (x > y)
{
return x;
}
else
{
return y;
}
}
} // Namespace detail
template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
inline constexpr Real fmax(Real x, Real y) noexcept
{
if (BOOST_MATH_IS_CONSTANT_EVALUATED(x))
{
return boost::math::ccmath::isnan(x) && boost::math::ccmath::isnan(y) ? std::numeric_limits<Real>::quiet_NaN() :
boost::math::ccmath::isnan(x) ? y :
boost::math::ccmath::isnan(y) ? x :
boost::math::ccmath::detail::fmax_impl(x, y);
}
else
{
using std::fmax;
return fmax(x, y);
}
}
template <typename T1, typename T2>
inline constexpr auto fmax(T1 x, T2 y) noexcept
{
if (BOOST_MATH_IS_CONSTANT_EVALUATED(x))
{
// If the type is an integer (e.g. epsilon == 0) then set the epsilon value to 1 so that type is at a minimum
// cast to double
constexpr auto T1p = std::numeric_limits<T1>::epsilon() > 0 ? std::numeric_limits<T1>::epsilon() : 1;
constexpr auto T2p = std::numeric_limits<T2>::epsilon() > 0 ? std::numeric_limits<T2>::epsilon() : 1;
using promoted_type =
#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
std::conditional_t<T1p <= LDBL_EPSILON && T1p <= T2p, T1,
std::conditional_t<T2p <= LDBL_EPSILON && T2p <= T1p, T2,
#endif
std::conditional_t<T1p <= DBL_EPSILON && T1p <= T2p, T1,
std::conditional_t<T2p <= DBL_EPSILON && T2p <= T1p, T2, double
#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
>>>>;
#else
>>;
#endif
return boost::math::ccmath::fmax(promoted_type(x), promoted_type(y));
}
else
{
using std::fmax;
return fmax(x, y);
}
}
inline constexpr float fmaxf(float x, float y) noexcept
{
return boost::math::ccmath::fmax(x, y);
}
#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
inline constexpr long double fmaxl(long double x, long double y) noexcept
{
return boost::math::ccmath::fmax(x, y);
}
#endif
} // Namespace boost::math::ccmath
#endif // BOOST_MATH_CCMATH_FMAX_HPP