text: ///////////////////////////////////////////////////////////////////////////////
  //  Copyright 2016 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_0.txt)
  
  
  #include <boost/multiprecision/cpp_bin_float.hpp>
  
  int main()
  {
     typedef boost::multiprecision::number<boost::multiprecision::backends::cpp_bin_float<256> > ext_float_t;
     typedef boost::multiprecision::number<boost::multiprecision::backends::cpp_bin_float<2046> > long_ext_float_t;
  
     ext_float_t x = 5e15;
     x += 0.5;
     ext_float_t x1 = x + 255.0 / (1 << 20); // + 2^-12 - eps
     ext_float_t x2 = x + 257.0 / (1 << 20); // + 2^-12 + eps
     double d1 = x1.convert_to<double>();
     double d2 = x2.convert_to<double>();
  
     std::cout << std::setprecision(18) << d1 << std::endl;
     std::cout << std::setprecision(18) << d2 << std::endl;
  
     x = 1e7 + 0.5;
     x1 = x + ldexp(255.0, -38); // + 2^-30 - eps
     x2 = x + ldexp(257.0, -38); // + 2^-30 + eps
     float f1 = x1.convert_to<float>();
     float f2 = x2.convert_to<float>();
  
     std::cout << std::setprecision(9) << f1 << std::endl;
     std::cout << std::setprecision(9) << f2 << std::endl;
  
     long_ext_float_t lf(1);
     lf += std::numeric_limits<long_ext_float_t>::epsilon();
     lf += std::numeric_limits<float>::epsilon() / 2;
     BOOST_ASSERT(lf != 1);
     float f3 = lf.convert_to<float>();
     std::cout << std::setprecision(9) << f3 << std::endl;
  
     return (d1 == d2) && (f1 == f2) && (f3 != 1) ? 0 : 1;
  }
  
  