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3rdparty/boost_1_81_0/boost/numeric/interval/constants.hpp 3.1 KB
63e88f80   Hu Chunming   提交三方库
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  /* Boost interval/constants.hpp template implementation file
   *
   * Copyright 2002 Hervé Brönnimann, Guillaume Melquiond, Sylvain Pion
   *
   * Distributed under 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_NUMERIC_INTERVAL_CONSTANTS_HPP
  #define BOOST_NUMERIC_INTERVAL_CONSTANTS_HPP
  
  namespace boost {
  namespace numeric {
  namespace interval_lib {
  namespace constants {
  
  // These constants should be exactly computed.
  // Decimal representations wouldn't do it since the standard doesn't
  // specify the rounding (even nearest) that should be used.
  
  static const float pi_f_l = 13176794.0f/(1<<22);
  static const float pi_f_u = 13176795.0f/(1<<22);
  static const double pi_d_l = (3373259426.0 + 273688.0 / (1<<21)) / (1<<30);
  static const double pi_d_u = (3373259426.0 + 273689.0 / (1<<21)) / (1<<30);
  
  template<class T> inline T pi_lower() { return 3; }
  template<class T> inline T pi_upper() { return 4; }
  template<class T> inline T pi_half_lower() { return 1; }
  template<class T> inline T pi_half_upper() { return 2; }
  template<class T> inline T pi_twice_lower() { return 6; }
  template<class T> inline T pi_twice_upper() { return 7; }
  
  template<> inline float pi_lower<float>() { return pi_f_l; }
  template<> inline float pi_upper<float>() { return pi_f_u; }
  template<> inline float pi_half_lower<float>() { return pi_f_l / 2; }
  template<> inline float pi_half_upper<float>() { return pi_f_u / 2; }
  template<> inline float pi_twice_lower<float>() { return pi_f_l * 2; }
  template<> inline float pi_twice_upper<float>() { return pi_f_u * 2; }
  
  template<> inline double pi_lower<double>() { return pi_d_l; }
  template<> inline double pi_upper<double>() { return pi_d_u; }
  template<> inline double pi_half_lower<double>() { return pi_d_l / 2; }
  template<> inline double pi_half_upper<double>() { return pi_d_u / 2; }
  template<> inline double pi_twice_lower<double>() { return pi_d_l * 2; }
  template<> inline double pi_twice_upper<double>() { return pi_d_u * 2; }
  
  template<> inline long double pi_lower<long double>() { return pi_d_l; }
  template<> inline long double pi_upper<long double>() { return pi_d_u; }
  template<> inline long double pi_half_lower<long double>() { return pi_d_l / 2; }
  template<> inline long double pi_half_upper<long double>() { return pi_d_u / 2; }
  template<> inline long double pi_twice_lower<long double>() { return pi_d_l * 2; }
  template<> inline long double pi_twice_upper<long double>() { return pi_d_u * 2; }
  
  } // namespace constants
  
  template<class I> inline
  I pi()
  {
    typedef typename I::base_type T;
    return I(constants::pi_lower<T>(),
             constants::pi_upper<T>(), true);
  }
  
  template<class I> inline
  I pi_half()
  {
    typedef typename I::base_type T;
    return I(constants::pi_half_lower<T>(),
             constants::pi_half_upper<T>(), true);
  }
  
  template<class I> inline
  I pi_twice()
  {
    typedef typename I::base_type T;
    return I(constants::pi_twice_lower<T>(),
             constants::pi_twice_upper<T>(), true);
  }
  
  } // namespace interval_lib
  } // namespace numeric
  } // namespace boost
  
  #endif // BOOST_NUMERIC_INTERVAL_CONSTANTS_HPP