math/ccmath/scalbn.hpp

0001 //  (C) Copyright Matt Borland 2021.
0002 //  (C) Copyright John Maddock 2021.
0003 //  Use, modification and distribution are subject to the
0004 //  Boost Software License, Version 1.0. (See accompanying file
0005 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006
0007 #ifndef BOOST_MATH_CCMATH_SCALBN_HPP
0008 #define BOOST_MATH_CCMATH_SCALBN_HPP
0009
0010 #include <boost/math/ccmath/detail/config.hpp>
0011
0012 #ifdef BOOST_MATH_NO_CCMATH
0013 #error "The header <boost/math/scalbn.hpp> can only be used in C++17 and later."
0014 #endif
0015
0016 #include <cfloat>
0017 #include <boost/math/ccmath/abs.hpp>
0018 #include <boost/math/ccmath/isinf.hpp>
0019 #include <boost/math/ccmath/isnan.hpp>
0020
0021 namespace boost::math::ccmath {
0022
0023 namespace detail {
0024
0025 template <typename Real, typename Z>
0026 inline constexpr Real scalbn_impl(Real arg, Z exp) noexcept
0027 {
0028     while(exp > 0)
0029     {
0030         arg *= FLT_RADIX;
0031         --exp;
0032     }
0033     while(exp < 0)
0034     {
0035         arg /= FLT_RADIX;
0036         ++exp;
0037     }
0038
0039     return arg;
0040 }
0041
0042 } // Namespace detail
0043
0044 template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
0045 inline constexpr Real scalbn(Real arg, int exp) noexcept
0046 {
0047     if(BOOST_MATH_IS_CONSTANT_EVALUATED(arg))
0048     {
0049         return boost::math::ccmath::abs(arg) == Real(0) ? arg :
0050                boost::math::ccmath::isinf(arg) ? arg :
0051                boost::math::ccmath::isnan(arg) ? arg :
0052                boost::math::ccmath::detail::scalbn_impl(arg, exp);
0053     }
0054     else
0055     {
0056         using std::scalbn;
0057         return scalbn(arg, exp);
0058     }
0059 }
0060
0061 template <typename Z, std::enable_if_t<std::is_integral_v<Z>, bool> = true>
0062 inline constexpr double scalbn(Z arg, int exp) noexcept
0063 {
0064     return boost::math::ccmath::scalbn(static_cast<double>(arg), exp);
0065 }
0066
0067 inline constexpr float scalbnf(float arg, int exp) noexcept
0068 {
0069     return boost::math::ccmath::scalbn(arg, exp);
0070 }
0071
0072 #ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
0073 inline constexpr long double scalbnl(long double arg, int exp) noexcept
0074 {
0075     return boost::math::ccmath::scalbn(arg, exp);
0076 }
0077 #endif
0078
0079 } // Namespaces
0080
0081 #endif // BOOST_MATH_CCMATH_SCALBN_HPP