text: ///////////////////////////////////////////////////////////////
  //  Copyright 2012 John Maddock. 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_
  
  #ifndef BOOST_MATH_CONCEPTS_ER_HPP
  #define BOOST_MATH_CONCEPTS_ER_HPP
  
  #include <iostream>
  #include <sstream>
  #include <iomanip>
  #include <cmath>
  #include <boost/cstdint.hpp>
  #include <boost/multiprecision/number.hpp>
  #include <boost/math/special_functions/fpclassify.hpp>
  #include <boost/mpl/list.hpp>
  
  namespace boost{
  namespace multiprecision{
  namespace concepts{
  
  #ifdef BOOST_MSVC
  #pragma warning(push)
  #pragma warning(disable:4244)
  #endif
  
  struct number_backend_float_architype
  {
     typedef mpl::list<boost::long_long_type>                 signed_types;
     typedef mpl::list<boost::ulong_long_type>        unsigned_types;
     typedef mpl::list<long double>               float_types;
     typedef int                                  exponent_type;
  
     number_backend_float_architype()
     {
        std::cout << "Default construct" << std::endl;
     }
     number_backend_float_architype(const number_backend_float_architype& o)
     {
        std::cout << "Copy construct" << std::endl;
        m_value = o.m_value;
     }
     number_backend_float_architype& operator = (const number_backend_float_architype& o)
     {
        m_value = o.m_value;
        std::cout << "Assignment (" << m_value << ")" << std::endl;
        return *this;
     }
     number_backend_float_architype& operator = (boost::ulong_long_type i)
     {
        m_value = i;
        std::cout << "UInt Assignment (" << i << ")" << std::endl;
        return *this;
     }
     number_backend_float_architype& operator = (boost::long_long_type i)
     {
        m_value = i;
        std::cout << "Int Assignment (" << i << ")" << std::endl;
        return *this;
     }
     number_backend_float_architype& operator = (long double d)
     {
        m_value = d;
        std::cout << "long double Assignment (" << d << ")" << std::endl;
        return *this;
     }
     number_backend_float_architype& operator = (const char* s)
     {
  #ifndef BOOST_NO_EXCEPTIONS
        try
        {
  #endif
           m_value = boost::lexical_cast<long double>(s);
  #ifndef BOOST_NO_EXCEPTIONS
        }
        catch(const std::exception&)
        {
           BOOST_THROW_EXCEPTION(std::runtime_error(std::string("Unable to parse input string: \"") + s + std::string("\" as a valid floating point number.")));
        }
  #endif
        std::cout << "const char* Assignment (" << s << ")" << std::endl;
        return *this;
     }
     void swap(number_backend_float_architype& o)
     {
        std::cout << "Swapping (" << m_value << " with " << o.m_value << ")" << std::endl;
        std::swap(m_value, o.m_value);
     }
     std::string str(std::streamsize digits, std::ios_base::fmtflags f)const
     {
        std::stringstream ss;
        ss.flags(f);
        if(digits)
           ss.precision(digits);
        else
           ss.precision(std::numeric_limits<long double>::digits10 + 3);
        boost::intmax_t i = m_value;
        boost::uintmax_t u = m_value;
        if(!(f & std::ios_base::scientific) && m_value == i)
           ss << i;
        else if(!(f & std::ios_base::scientific) && m_value == u)
           ss << u;
        else
           ss << m_value;
        std::string s = ss.str();
        std::cout << "Converting to string (" << s << ")" << std::endl;
        return s;
     }
     void negate()
     {
        std::cout << "Negating (" << m_value << ")" << std::endl;
        m_value = -m_value;
     }
     int compare(const number_backend_float_architype& o)const
     {
        std::cout << "Comparison" << std::endl;
        return m_value > o.m_value ? 1 : (m_value < o.m_value ? -1 : 0);
     }
     int compare(boost::long_long_type i)const
     {
        std::cout << "Comparison with int" << std::endl;
        return m_value > i ? 1 : (m_value < i ? -1 : 0);
     }
     int compare(boost::ulong_long_type i)const
     {
        std::cout << "Comparison with unsigned" << std::endl;
        return m_value > i ? 1 : (m_value < i ? -1 : 0);
     }
     int compare(long double d)const
     {
        std::cout << "Comparison with long double" << std::endl;
        return m_value > d ? 1 : (m_value < d ? -1 : 0);
     }
     long double m_value;
  };
  
  inline void eval_add(number_backend_float_architype& result, const number_backend_float_architype& o)
  {
     std::cout << "Addition (" << result.m_value << " += " << o.m_value << ")" << std::endl;
     result.m_value += o.m_value;
  }
  inline void eval_subtract(number_backend_float_architype& result, const number_backend_float_architype& o)
  {
     std::cout << "Subtraction (" << result.m_value << " -= " << o.m_value << ")" << std::endl;
     result.m_value -= o.m_value;
  }
  inline void eval_multiply(number_backend_float_architype& result, const number_backend_float_architype& o)
  {
     std::cout << "Multiplication (" << result.m_value << " *= " << o.m_value << ")" << std::endl;
     result.m_value *= o.m_value;
  }
  inline void eval_divide(number_backend_float_architype& result, const number_backend_float_architype& o)
  {
     std::cout << "Division (" << result.m_value << " /= " << o.m_value << ")" << std::endl;
     result.m_value /= o.m_value;
  }
  
  inline void eval_convert_to(boost::ulong_long_type* result, const number_backend_float_architype& val)
  {
     *result = static_cast<boost::ulong_long_type>(val.m_value);
  }
  inline void eval_convert_to(boost::long_long_type* result, const number_backend_float_architype& val)
  {
     *result = static_cast<boost::long_long_type>(val.m_value);
  }
  inline void eval_convert_to(long double* result, number_backend_float_architype& val)
  {
     *result = val.m_value;
  }
  
  inline void eval_frexp(number_backend_float_architype& result, const number_backend_float_architype& arg, int* exp)
  {
     result = std::frexp(arg.m_value, exp);
  }
  
  inline void eval_ldexp(number_backend_float_architype& result, const number_backend_float_architype& arg, int exp)
  {
     result = std::ldexp(arg.m_value, exp);
  }
  
  inline void eval_floor(number_backend_float_architype& result, const number_backend_float_architype& arg)
  {
     result = std::floor(arg.m_value);
  }
  
  inline void eval_ceil(number_backend_float_architype& result, const number_backend_float_architype& arg)
  {
     result = std::ceil(arg.m_value);
  }
  
  inline void eval_sqrt(number_backend_float_architype& result, const number_backend_float_architype& arg)
  {
     result = std::sqrt(arg.m_value);
  }
  
  inline int eval_fpclassify(const number_backend_float_architype& arg)
  {
     return (boost::math::fpclassify)(arg.m_value);
  }
  
  typedef boost::multiprecision::number<number_backend_float_architype> mp_number_float_architype;
  
  } // namespace
  
  template<>
  struct number_category<concepts::number_backend_float_architype> : public mpl::int_<number_kind_floating_point>{};
  
  }} // namespaces
  
  namespace std{
  
  template <boost::multiprecision::expression_template_option ExpressionTemplates>
  class numeric_limits<boost::multiprecision::number<boost::multiprecision::concepts::number_backend_float_architype, ExpressionTemplates> > : public std::numeric_limits<long double>
  {
     typedef std::numeric_limits<long double> base_type;
     typedef boost::multiprecision::number<boost::multiprecision::concepts::number_backend_float_architype, ExpressionTemplates> number_type;
  public:
     static number_type (min)() BOOST_NOEXCEPT { return (base_type::min)(); }
     static number_type (max)() BOOST_NOEXCEPT { return (base_type::max)(); }
     static number_type lowest() BOOST_NOEXCEPT { return -(max)(); }
     static number_type epsilon() BOOST_NOEXCEPT { return base_type::epsilon(); }
     static number_type round_error() BOOST_NOEXCEPT { return base_type::round_error(); }
     static number_type infinity() BOOST_NOEXCEPT { return base_type::infinity(); }
     static number_type quiet_NaN() BOOST_NOEXCEPT { return base_type::quiet_NaN(); }
     static number_type signaling_NaN() BOOST_NOEXCEPT { return base_type::signaling_NaN(); }
     static number_type denorm_min() BOOST_NOEXCEPT { return base_type::denorm_min(); }
  };
  
  }
  
  #ifdef BOOST_MSVC
  #pragma warning(pop)
  #endif
  
  #endif
  