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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