585da50d7d
This PR adds the code of Boost.Math as of version 1.89 into the third-party directory, as discussed in a recent RFC [1]. The goal is for this code to be used as a back-end for the C++17 Math Special Functions. As explained in third-paty/README.md, this code is cleared for usage inside libc++ for the Math Special functions, however the LLVM Foundation should be consulted before using this code anywhere else in the LLVM project, due to the fact that it is under the Boost Software License (as opposed to the usual LLVM license). See the RFC [1] for more details. [1]: https://discourse.llvm.org/t/rfc-libc-taking-a-dependency-on-boost-math-for-the-c-17-math-special-functions
94 lines
2.1 KiB
C++
94 lines
2.1 KiB
C++
// (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_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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