numeric/interval/constants.hpp

0001 /* Boost interval/constants.hpp template implementation file
0002  *
0003  * Copyright 2002 Hervé Brönnimann, Guillaume Melquiond, Sylvain Pion
0004  *
0005  * Distributed under the Boost Software License, Version 1.0.
0006  * (See accompanying file LICENSE_1_0.txt or
0007  * copy at http://www.boost.org/LICENSE_1_0.txt)
0008  */
0009
0010 #ifndef BOOST_NUMERIC_INTERVAL_CONSTANTS_HPP
0011 #define BOOST_NUMERIC_INTERVAL_CONSTANTS_HPP
0012
0013 namespace boost {
0014 namespace numeric {
0015 namespace interval_lib {
0016 namespace constants {
0017
0018 // These constants should be exactly computed.
0019 // Decimal representations wouldn't do it since the standard doesn't
0020 // specify the rounding (even nearest) that should be used.
0021
0022 static const float pi_f_l = 13176794.0f/(1<<22);
0023 static const float pi_f_u = 13176795.0f/(1<<22);
0024 static const double pi_d_l = (3373259426.0 + 273688.0 / (1<<21)) / (1<<30);
0025 static const double pi_d_u = (3373259426.0 + 273689.0 / (1<<21)) / (1<<30);
0026
0027 template<class T> inline T pi_lower() { return 3; }
0028 template<class T> inline T pi_upper() { return 4; }
0029 template<class T> inline T pi_half_lower() { return 1; }
0030 template<class T> inline T pi_half_upper() { return 2; }
0031 template<class T> inline T pi_twice_lower() { return 6; }
0032 template<class T> inline T pi_twice_upper() { return 7; }
0033
0034 template<> inline float pi_lower<float>() { return pi_f_l; }
0035 template<> inline float pi_upper<float>() { return pi_f_u; }
0036 template<> inline float pi_half_lower<float>() { return pi_f_l / 2; }
0037 template<> inline float pi_half_upper<float>() { return pi_f_u / 2; }
0038 template<> inline float pi_twice_lower<float>() { return pi_f_l * 2; }
0039 template<> inline float pi_twice_upper<float>() { return pi_f_u * 2; }
0040
0041 template<> inline double pi_lower<double>() { return pi_d_l; }
0042 template<> inline double pi_upper<double>() { return pi_d_u; }
0043 template<> inline double pi_half_lower<double>() { return pi_d_l / 2; }
0044 template<> inline double pi_half_upper<double>() { return pi_d_u / 2; }
0045 template<> inline double pi_twice_lower<double>() { return pi_d_l * 2; }
0046 template<> inline double pi_twice_upper<double>() { return pi_d_u * 2; }
0047
0048 template<> inline long double pi_lower<long double>() { return pi_d_l; }
0049 template<> inline long double pi_upper<long double>() { return pi_d_u; }
0050 template<> inline long double pi_half_lower<long double>() { return pi_d_l / 2; }
0051 template<> inline long double pi_half_upper<long double>() { return pi_d_u / 2; }
0052 template<> inline long double pi_twice_lower<long double>() { return pi_d_l * 2; }
0053 template<> inline long double pi_twice_upper<long double>() { return pi_d_u * 2; }
0054
0055 } // namespace constants
0056
0057 template<class I> inline
0058 I pi()
0059 {
0060   typedef typename I::base_type T;
0061   return I(constants::pi_lower<T>(),
0062            constants::pi_upper<T>(), true);
0063 }
0064
0065 template<class I> inline
0066 I pi_half()
0067 {
0068   typedef typename I::base_type T;
0069   return I(constants::pi_half_lower<T>(),
0070            constants::pi_half_upper<T>(), true);
0071 }
0072
0073 template<class I> inline
0074 I pi_twice()
0075 {
0076   typedef typename I::base_type T;
0077   return I(constants::pi_twice_lower<T>(),
0078            constants::pi_twice_upper<T>(), true);
0079 }
0080
0081 } // namespace interval_lib
0082 } // namespace numeric
0083 } // namespace boost
0084
0085 #endif // BOOST_NUMERIC_INTERVAL_CONSTANTS_HPP