94 lines
2.1 KiB
C++
94 lines
2.1 KiB
C++
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// (C) Copyright Matt Borland 2022.
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MATH_CCMATH_FDIM_HPP
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#define BOOST_MATH_CCMATH_FDIM_HPP
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#include <boost/math/ccmath/detail/config.hpp>
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#ifdef BOOST_MATH_NO_CCMATH
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#error "The header <boost/math/fdim.hpp> can only be used in C++17 and later."
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#endif
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#include <boost/math/tools/promotion.hpp>
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#include <boost/math/ccmath/isnan.hpp>
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namespace boost::math::ccmath {
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namespace detail {
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template <typename T>
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constexpr T fdim_impl(const T x, const T y) noexcept
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{
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if (x <= y)
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{
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return 0;
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}
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else if ((y < 0) && (x > (std::numeric_limits<T>::max)() + y))
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{
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return std::numeric_limits<T>::infinity();
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}
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else
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{
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return x - y;
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}
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}
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} // Namespace detail
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template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
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constexpr Real fdim(Real x, Real y) noexcept
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{
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if (BOOST_MATH_IS_CONSTANT_EVALUATED(x))
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{
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if (boost::math::ccmath::isnan(x))
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{
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return x;
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}
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else if (boost::math::ccmath::isnan(y))
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{
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return y;
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}
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return boost::math::ccmath::detail::fdim_impl(x, y);
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}
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else
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{
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using std::fdim;
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return fdim(x, y);
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}
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}
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template <typename T1, typename T2>
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constexpr auto fdim(T1 x, T2 y) noexcept
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{
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if (BOOST_MATH_IS_CONSTANT_EVALUATED(x))
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{
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using promoted_type = boost::math::tools::promote_args_2_t<T1, T2>;
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return boost::math::ccmath::fdim(promoted_type(x), promoted_type(y));
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}
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else
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{
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using std::fdim;
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return fdim(x, y);
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}
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}
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constexpr float fdimf(float x, float y) noexcept
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{
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return boost::math::ccmath::fdim(x, y);
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}
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#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
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constexpr long double fdiml(long double x, long double y) noexcept
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{
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return boost::math::ccmath::fdim(x, y);
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}
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#endif
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} // Namespace boost::math::ccmath
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#endif // BOOST_MATH_CCMATH_FDIM_HPP
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