| // 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 |
| */ |