129 lines
4.2 KiB
C++
129 lines
4.2 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_FMA_HPP
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#define BOOST_MATH_CCMATH_FMA_HPP
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#include <cmath>
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#include <limits>
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#include <type_traits>
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#include <boost/math/tools/is_constant_evaluated.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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namespace boost::math::ccmath {
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namespace detail {
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template <typename T>
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constexpr T fma_imp(const T x, const T y, const T z) noexcept
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{
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#if defined(__GNUC__) && !defined(__clang__) && !defined(__INTEL_COMPILER) && !defined(__INTEL_LLVM_COMPILER)
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if constexpr (std::is_same_v<T, float>)
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{
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return __builtin_fmaf(x, y, z);
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}
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else if constexpr (std::is_same_v<T, double>)
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{
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return __builtin_fma(x, y, z);
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}
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else if constexpr (std::is_same_v<T, long double>)
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{
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return __builtin_fmal(x, y, z);
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}
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#endif
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// If we can't use compiler intrinsics hope that -fma flag optimizes this call to fma instruction
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return (x * y) + z;
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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 fma(Real x, Real y, Real z) 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 (x == 0 && boost::math::ccmath::isinf(y))
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{
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return std::numeric_limits<Real>::quiet_NaN();
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}
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else if (y == 0 && boost::math::ccmath::isinf(x))
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{
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return std::numeric_limits<Real>::quiet_NaN();
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}
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else if (boost::math::ccmath::isnan(x))
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{
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return std::numeric_limits<Real>::quiet_NaN();
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}
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else if (boost::math::ccmath::isnan(y))
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{
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return std::numeric_limits<Real>::quiet_NaN();
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}
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else if (boost::math::ccmath::isnan(z))
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{
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return std::numeric_limits<Real>::quiet_NaN();
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}
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return boost::math::ccmath::detail::fma_imp(x, y, z);
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}
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else
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{
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using std::fma;
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return fma(x, y, z);
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}
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}
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template <typename T1, typename T2, typename T3>
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constexpr auto fma(T1 x, T2 y, T3 z) 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 the type is an integer (e.g. epsilon == 0) then set the epsilon value to 1 so that type is at a minimum
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// cast to double
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constexpr auto T1p = std::numeric_limits<T1>::epsilon() > 0 ? std::numeric_limits<T1>::epsilon() : 1;
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constexpr auto T2p = std::numeric_limits<T2>::epsilon() > 0 ? std::numeric_limits<T2>::epsilon() : 1;
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constexpr auto T3p = std::numeric_limits<T3>::epsilon() > 0 ? std::numeric_limits<T3>::epsilon() : 1;
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using promoted_type =
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#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
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std::conditional_t<T1p <= LDBL_EPSILON && T1p <= T2p, T1,
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std::conditional_t<T2p <= LDBL_EPSILON && T2p <= T1p, T2,
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std::conditional_t<T3p <= LDBL_EPSILON && T3p <= T2p, T3,
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#endif
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std::conditional_t<T1p <= DBL_EPSILON && T1p <= T2p, T1,
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std::conditional_t<T2p <= DBL_EPSILON && T2p <= T1p, T2,
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std::conditional_t<T3p <= DBL_EPSILON && T3p <= T2p, T3, double
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#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
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>>>>>>;
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#else
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>>>;
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#endif
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return boost::math::ccmath::fma(promoted_type(x), promoted_type(y), promoted_type(z));
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}
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else
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{
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using std::fma;
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return fma(x, y, z);
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}
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}
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constexpr float fmaf(float x, float y, float z) noexcept
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{
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return boost::math::ccmath::fma(x, y, z);
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}
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#ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
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constexpr long double fmal(long double x, long double y, long double z) noexcept
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{
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return boost::math::ccmath::fma(x, y, z);
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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_FMA_HPP
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