WSJT-X/boost/libs/math/example/policy_eg_2.cpp

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// Copyright John Maddock 2007.
// Copyright Paul A. Bristow 2010
// Use, modification and distribution are subject to 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 <iostream>
using std::cout; using std::endl;
#include <cerrno> // for ::errno
//[policy_eg_2
#include <boost/math/special_functions/gamma.hpp>
using boost::math::tgamma;
int main()
{
// using namespace boost::math::policies; // or
using boost::math::policies::errno_on_error;
using boost::math::policies::make_policy;
using boost::math::policies::pole_error;
using boost::math::policies::domain_error;
using boost::math::policies::overflow_error;
using boost::math::policies::evaluation_error;
errno = 0;
std::cout << "Result of tgamma(30000) is: "
<< boost::math::tgamma(
30000,
make_policy(
domain_error<errno_on_error>(),
pole_error<errno_on_error>(),
overflow_error<errno_on_error>(),
evaluation_error<errno_on_error>()
)
) << std::endl;
// Check errno was set:
std::cout << "errno = " << errno << std::endl;
// and again with evaluation at a pole:
std::cout << "Result of tgamma(-10) is: "
<< boost::math::tgamma(
-10,
make_policy(
domain_error<errno_on_error>(),
pole_error<errno_on_error>(),
overflow_error<errno_on_error>(),
evaluation_error<errno_on_error>()
)
) << std::endl;
// Check errno was set:
std::cout << "errno = " << errno << std::endl;
}
//] //[/policy_eg_2]
/*
Output:
Result of tgamma(30000) is: 1.#INF
errno = 34
Result of tgamma(-10) is: 1.#QNAN
errno = 33
*/