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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)
// Note that this file contains quickbook mark-up as well as code
// and comments, don't change any of the special comment mark-ups!
//[policy_ref_snip1
#include <boost/math/special_functions/gamma.hpp>
using boost::math::tgamma;
//using namespace boost::math::policies; may also be convenient.
using boost::math::policies::policy;
using boost::math::policies::evaluation_error;
using boost::math::policies::domain_error;
using boost::math::policies::overflow_error;
using boost::math::policies::domain_error;
using boost::math::policies::pole_error;
using boost::math::policies::errno_on_error;
// Define a policy:
typedef policy<
domain_error<errno_on_error>,
pole_error<errno_on_error>,
overflow_error<errno_on_error>,
evaluation_error<errno_on_error>
> my_policy;
double my_value = 0.; //
// Call the function applying my_policy:
double t1 = tgamma(my_value, my_policy());
// Alternatively (and equivalently) we could use helpful function
// make_policy and define everything at the call site:
double t2 = tgamma(my_value,
make_policy(
domain_error<errno_on_error>(),
pole_error<errno_on_error>(),
overflow_error<errno_on_error>(),
evaluation_error<errno_on_error>() )
);
//]
#include <iostream>
using std::cout; using std::endl;
int main()
{
cout << "my_value = " << my_value << endl;
try
{ // First with default policy - throw an exception.
cout << "tgamma(my_value) = " << tgamma(my_value) << endl;
}
catch(const std::exception& e)
{
cout <<"\n""Message from thrown exception was:\n " << e.what() << endl;
}
cout << "tgamma(my_value, my_policy() = " << t1 << endl;
cout << "tgamma(my_value, make_policy(domain_error<errno_on_error>(), pole_error<errno_on_error>(), overflow_error<errno_on_error>(), evaluation_error<errno_on_error>() ) = " << t2 << endl;
}
/*
Output:
my_value = 0
Message from thrown exception was:
Error in function boost::math::tgamma<long double>(long double): Evaluation of tgamma at a negative integer 0.
tgamma(my_value, my_policy() = 1.#QNAN
tgamma(my_value, make_policy(domain_error<errno_on_error>(), pole_error<errno_on_error>(), overflow_error<errno_on_error>(), evaluation_error<errno_on_error>() ) = 1.#QNAN
*/
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