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
132 lines
2.7 KiB
C++
132 lines
2.7 KiB
C++
// (C) Copyright Matt Borland 2021.
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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_FLOOR_HPP
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#define BOOST_MATH_CCMATH_FLOOR_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/floor.hpp> can only be used in C++17 and later."
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#endif
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#include <boost/math/ccmath/abs.hpp>
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#include <boost/math/ccmath/isinf.hpp>
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#include <boost/math/ccmath/isnan.hpp>
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#include <limits>
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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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inline constexpr T floor_pos_impl(T arg) noexcept
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{
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constexpr auto max_comp_val = T(1) / std::numeric_limits<T>::epsilon();
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if (arg >= max_comp_val)
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{
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return arg;
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}
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T result = 1;
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if(result <= arg)
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{
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while(result < arg)
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{
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result *= 2;
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}
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while(result > arg)
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{
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--result;
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}
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return result;
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}
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else
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{
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return T(0);
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}
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}
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template <typename T>
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inline constexpr T floor_neg_impl(T arg) noexcept
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{
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T result = -1;
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if(result > arg)
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{
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while(result > arg)
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{
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result *= 2;
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}
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while(result < arg)
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{
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++result;
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}
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if(result != arg)
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{
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--result;
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}
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}
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return result;
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}
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template <typename T>
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inline constexpr T floor_impl(T arg) noexcept
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{
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if(arg > 0)
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{
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return floor_pos_impl(arg);
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}
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else
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{
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return floor_neg_impl(arg);
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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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inline constexpr Real floor(Real arg) noexcept
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{
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if(BOOST_MATH_IS_CONSTANT_EVALUATED(arg))
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{
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return boost::math::ccmath::abs(arg) == Real(0) ? arg :
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boost::math::ccmath::isinf(arg) ? arg :
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boost::math::ccmath::isnan(arg) ? arg :
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boost::math::ccmath::detail::floor_impl(arg);
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}
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else
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{
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using std::floor;
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return floor(arg);
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}
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}
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template <typename Z, std::enable_if_t<std::is_integral_v<Z>, bool> = true>
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inline constexpr double floor(Z arg) noexcept
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{
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return boost::math::ccmath::floor(static_cast<double>(arg));
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}
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inline constexpr float floorf(float arg) noexcept
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{
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return boost::math::ccmath::floor(arg);
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}
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#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
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inline constexpr long double floorl(long double arg) noexcept
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{
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return boost::math::ccmath::floor(arg);
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}
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#endif
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} // Namespaces
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#endif // BOOST_MATH_CCMATH_FLOOR_HPP
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