ceph/src/boost/libs/multiprecision/example/float128_snips.cpp

   1 ///////////////////////////////////////////////////////////////
   2 //  Copyright 2013 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 //[float128_eg
   7 #include <boost/multiprecision/float128.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 128-bit precision and full numeric_limits support:
  16    float128 b = 2;
  17    // There are 113-bits of precision:
  18    std::cout << std::numeric_limits<float128>::digits << std::endl;
  19    // Or 34 decimal places:
  20    std::cout << std::numeric_limits<float128>::digits10 << std::endl;
  21    // We can use any C++ std lib function, lets print all the digits as well:
  22    std::cout << std::setprecision(std::numeric_limits<float128>::max_digits10)
  23       << log(b) << std::endl; // print log(2) = 0.693147180559945309417232121458176575
  24    // We can also use any function from Boost.Math:
  25    std::cout << boost::math::tgamma(b) << std::endl;
  26    // And since we have an extended exponent range we can generate some really large
  27    // numbers here (4.02387260077093773543702433923004111e+2564):
  28    std::cout << boost::math::tgamma(float128(1000)) << std::endl;
  29    //
  30    // We can declare constants using GCC or Intel's native types, and the Q suffix,
  31    // these can be declared constexpr if required:
  32    /*<-*/
  33 #ifndef BOOST_NO_CXX11_CONSTEXPR
  34    /*->*/
  35    constexpr float128 pi = 3.1415926535897932384626433832795028841971693993751058Q;
  36    /*<-*/
  37 #endif
  38    /*->*/
  39    return 0;
  40 }
  41 //]
  42