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3rdparty/boost_1_81_0/boost/math/ccmath/fmin.hpp 2.94 KB
63e88f80   Hu Chunming   提交三方库
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  //  (C) Copyright Matt Borland 2022.
  //  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_FMIN_HPP
  #define BOOST_MATH_CCMATH_FMIN_HPP
  
  #include <cmath>
  #include <limits>
  #include <type_traits>
  #include <boost/math/tools/is_constant_evaluated.hpp>
  #include <boost/math/ccmath/isnan.hpp>
  
  namespace boost::math::ccmath {
  
  namespace detail {
  
  template <typename T>
  inline constexpr T fmin_impl(const T x, const T y) noexcept
  {
      if (x < y)
      {
          return x;
      }
      else
      {
          return y;
      }
  }
  
  } // Namespace detail
  
  template <typename Real, std::enable_if_t<!std::is_integral_v<Real>, bool> = true>
  inline constexpr Real fmin(Real x, Real y) noexcept
  {
      if (BOOST_MATH_IS_CONSTANT_EVALUATED(x))
      {
          return boost::math::ccmath::isnan(x) && boost::math::ccmath::isnan(y) ? std::numeric_limits<Real>::quiet_NaN() :
                 boost::math::ccmath::isnan(x) ? y :
                 boost::math::ccmath::isnan(y) ? x :
                 boost::math::ccmath::detail::fmin_impl(x, y);
      }
      else
      {
          using std::fmin;
          return fmin(x, y);
      }
  }
  
  template <typename T1, typename T2>
  inline constexpr auto fmin(T1 x, T2 y) noexcept
  {
      if (BOOST_MATH_IS_CONSTANT_EVALUATED(x))
      {
          // If the type is an integer (e.g. epsilon == 0) then set the epsilon value to 1 so that type is at a minimum 
          // cast to double
          constexpr auto T1p = std::numeric_limits<T1>::epsilon() > 0 ? std::numeric_limits<T1>::epsilon() : 1;
          constexpr auto T2p = std::numeric_limits<T2>::epsilon() > 0 ? std::numeric_limits<T2>::epsilon() : 1;
          
          using promoted_type = 
                                #ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
                                std::conditional_t<T1p <= LDBL_EPSILON && T1p <= T2p, T1,
                                std::conditional_t<T2p <= LDBL_EPSILON && T2p <= T1p, T2,
                                #endif
                                std::conditional_t<T1p <= DBL_EPSILON && T1p <= T2p, T1,
                                std::conditional_t<T2p <= DBL_EPSILON && T2p <= T1p, T2, double
                                #ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
                                >>>>;
                                #else
                                >>;
                                #endif
  
          return boost::math::ccmath::fmin(promoted_type(x), promoted_type(y));
      }
      else
      {
          using std::fmin;
          return fmin(x, y);
      }
  }
  
  inline constexpr float fminf(float x, float y) noexcept
  {
      return boost::math::ccmath::fmin(x, y);
  }
  
  #ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
  inline constexpr long double fminl(long double x, long double y) noexcept
  {
      return boost::math::ccmath::fmin(x, y);
  }
  #endif
  
  } // Namespace boost::math::ccmath
  
  #endif // BOOST_MATH_CCMATH_FMIN_HPP