ceph/src/boost/libs/math/example/policy_eg_5.cpp

   1 //  Copyright John Maddock 2007.
   2 //  Copyright Paul A. Bristow 2010
   3 //  Use, modification and distribution are subject to the
   4 //  Boost Software License, Version 1.0. (See accompanying file
   5 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6
   7 // Note that this file contains quickbook mark-up as well as code
   8 // and comments, don't change any of the special comment mark-ups!
   9
  10 #include <iostream>
  11 using std::cout;  using std::endl;
  12 #include <cerrno> // for ::errno
  13
  14 //[policy_eg_5
  15
  16 #include <boost/math/special_functions.hpp>
  17 // using boost::math::tgamma; // Would create an ambiguity between
  18 // 'double boost::math::tgamma<int>(T)' and
  19 // 'double 'anonymous-namespace'::tgamma<int>(RT)'.
  20
  21 namespace mymath
  22 { // unnamed
  23
  24 using namespace boost::math::policies;
  25
  26 typedef policy<
  27    domain_error<errno_on_error>,
  28    pole_error<errno_on_error>,
  29    overflow_error<errno_on_error>,
  30    evaluation_error<errno_on_error>
  31 > c_policy;
  32
  33 BOOST_MATH_DECLARE_SPECIAL_FUNCTIONS(c_policy)
  34
  35 /*`
  36 So that when we call `mymath::tgamma(z)`, we really end up calling
  37  `boost::math::tgamma(z, anonymous-namespace::c_policy())`.
  38 */
  39
  40 } // close unnamed namespace
  41
  42 int main()
  43 {
  44    errno = 0;
  45    cout << "Result of tgamma(30000) is: "
  46       << mymath::tgamma(30000) << endl;
  47       // tgamma in unnamed namespace in this translation unit (file) only.
  48    cout << "errno = " << errno << endl;
  49    cout << "Result of tgamma(-10) is: "
  50       << mymath::tgamma(-10) << endl;
  51    cout << "errno = " << errno << endl;
  52    // Default tgamma policy would throw an exception, and abort.
  53 }
  54
  55 //] //[/policy_eg_5]
  56
  57 /*
  58 Output:
  59
  60   Result of tgamma(30000) is: 1.#INF
  61   errno = 34
  62   Result of tgamma(-10) is: 1.#QNAN
  63   errno = 33
  64
  65
  66 */