87 lines
3.2 KiB
C++
87 lines
3.2 KiB
C++
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// Copyright (c) 2011 John Maddock
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MATH_TOOLS_BIG_CONSTANT_HPP
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#define BOOST_MATH_TOOLS_BIG_CONSTANT_HPP
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#include <boost/math/tools/config.hpp>
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#ifndef BOOST_MATH_NO_LEXICAL_CAST
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#include <boost/lexical_cast.hpp>
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#endif
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#include <boost/type_traits/is_convertible.hpp>
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namespace boost{ namespace math{
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namespace tools{
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template <class T>
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struct numeric_traits : public std::numeric_limits< T > {};
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#ifdef BOOST_MATH_USE_FLOAT128
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typedef __float128 largest_float;
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#define BOOST_MATH_LARGEST_FLOAT_C(x) x##Q
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template <>
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struct numeric_traits<__float128>
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{
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static const int digits = 113;
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static const int digits10 = 33;
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static const int max_exponent = 16384;
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static const bool is_specialized = true;
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};
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#else
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typedef long double largest_float;
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#define BOOST_MATH_LARGEST_FLOAT_C(x) x##L
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#endif
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template <class T>
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inline BOOST_CONSTEXPR_OR_CONST T make_big_value(largest_float v, const char*, mpl::true_ const&, mpl::false_ const&) BOOST_MATH_NOEXCEPT(T)
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{
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return static_cast<T>(v);
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}
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template <class T>
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inline BOOST_CONSTEXPR_OR_CONST T make_big_value(largest_float v, const char*, mpl::true_ const&, mpl::true_ const&) BOOST_MATH_NOEXCEPT(T)
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{
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return static_cast<T>(v);
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}
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#ifndef BOOST_MATH_NO_LEXICAL_CAST
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template <class T>
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inline T make_big_value(largest_float, const char* s, mpl::false_ const&, mpl::false_ const&)
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{
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return boost::lexical_cast<T>(s);
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}
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#endif
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template <class T>
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inline BOOST_MATH_CONSTEXPR const char* make_big_value(largest_float, const char* s, mpl::false_ const&, mpl::true_ const&) BOOST_MATH_NOEXCEPT(T)
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{
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return s;
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}
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//
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// For constants which might fit in a long double (if it's big enough):
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//
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#define BOOST_MATH_BIG_CONSTANT(T, D, x)\
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boost::math::tools::make_big_value<T>(\
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BOOST_MATH_LARGEST_FLOAT_C(x), \
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BOOST_STRINGIZE(x), \
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mpl::bool_< (is_convertible<boost::math::tools::largest_float, T>::value) && \
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((D <= boost::math::tools::numeric_traits<boost::math::tools::largest_float>::digits) \
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|| is_floating_point<T>::value \
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|| (boost::math::tools::numeric_traits<T>::is_specialized && \
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(boost::math::tools::numeric_traits<T>::digits10 <= boost::math::tools::numeric_traits<boost::math::tools::largest_float>::digits10))) >(), \
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boost::is_convertible<const char*, T>())
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//
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// For constants too huge for any conceivable long double (and which generate compiler errors if we try and declare them as such):
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//
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#define BOOST_MATH_HUGE_CONSTANT(T, D, x)\
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boost::math::tools::make_big_value<T>(0.0L, BOOST_STRINGIZE(x), \
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mpl::bool_<is_floating_point<T>::value || (boost::math::tools::numeric_traits<T>::is_specialized && boost::math::tools::numeric_traits<T>::max_exponent <= boost::math::tools::numeric_traits<boost::math::tools::largest_float>::max_exponent && boost::math::tools::numeric_traits<T>::digits <= boost::math::tools::numeric_traits<boost::math::tools::largest_float>::digits)>(), \
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boost::is_convertible<const char*, T>())
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}}} // namespaces
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#endif
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