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- // (C) Copyright Matt Borland 2021.
- // Use, modification and distribution are subject to the
- // Boost Software License, Version 1.0. (See accompanying file
- // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
- #ifndef BOOST_MATH_CCMATH_ILOGB_HPP
- #define BOOST_MATH_CCMATH_ILOGB_HPP
- #include <boost/math/ccmath/detail/config.hpp>
- #ifdef BOOST_MATH_NO_CCMATH
- #error "The header <boost/math/ilogb.hpp> can only be used in C++17 and later."
- #endif
- #include <boost/math/ccmath/logb.hpp>
- #include <boost/math/ccmath/isinf.hpp>
- #include <boost/math/ccmath/isnan.hpp>
- #include <boost/math/ccmath/abs.hpp>
- namespace boost::math::ccmath {
- // If arg is not zero, infinite, or NaN, the value returned is exactly equivalent to static_cast<int>(std::logb(arg))
- template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
- inline constexpr int ilogb(Real arg) noexcept
- {
- if(BOOST_MATH_IS_CONSTANT_EVALUATED(arg))
- {
- return boost::math::ccmath::abs(arg) == Real(0) ? FP_ILOGB0 :
- boost::math::ccmath::isinf(arg) ? INT_MAX :
- boost::math::ccmath::isnan(arg) ? FP_ILOGBNAN :
- static_cast<int>(boost::math::ccmath::logb(arg));
- }
- else
- {
- using std::ilogb;
- return ilogb(arg);
- }
- }
- template <typename Z, std::enable_if_t<std::is_integral_v<Z>, bool> = true>
- inline constexpr int ilogb(Z arg) noexcept
- {
- return boost::math::ccmath::ilogb(static_cast<double>(arg));
- }
- inline constexpr int ilogbf(float arg) noexcept
- {
- return boost::math::ccmath::ilogb(arg);
- }
- #ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
- inline constexpr int ilogbl(long double arg) noexcept
- {
- return boost::math::ccmath::ilogb(arg);
- }
- #endif
- } // Namespaces
- #endif // BOOST_MATH_CCMATH_ILOGB_HPP
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