ceph/src/boost/libs/multiprecision/example/cpp_dec_float_snips.cpp

   1 ///////////////////////////////////////////////////////////////
   2 //  Copyright 2011 John Maddock. Distributed under the Boost
   3 //  Software License, Version 1.0. (See accompanying file
   4 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_
   5
   6    //[cpp_dec_float_eg
   7 #include <boost/multiprecision/cpp_dec_float.hpp>
   8 #include <boost/math/special_functions/gamma.hpp>
   9 #include <iostream>
  10
  11 int main()
  12 {
  13    using namespace boost::multiprecision;
  14
  15    // Operations at fixed precision and full numeric_limits support:
  16    cpp_dec_float_100 b = 2;
  17    std::cout << std::numeric_limits<cpp_dec_float_100>::digits << std::endl;
  18    // Note that digits10 is the same as digits, since we're base 10! :
  19    std::cout << std::numeric_limits<cpp_dec_float_100>::digits10 << std::endl;
  20    // We can use any C++ std lib function, lets print all the digits as well:
  21    std::cout << std::setprecision(std::numeric_limits<cpp_dec_float_100>::max_digits10)
  22       << log(b) << std::endl; // print log(2)
  23    // We can also use any function from Boost.Math:
  24    std::cout << boost::math::tgamma(b) << std::endl;
  25    // These even work when the argument is an expression template:
  26    std::cout << boost::math::tgamma(b * b) << std::endl;
  27    // And since we have an extended exponent range we can generate some really large
  28    // numbers here (4.0238726007709377354370243e+2564):
  29    std::cout << boost::math::tgamma(cpp_dec_float_100(1000)) << std::endl;
  30    return 0;
  31 }
  32 //]
  33