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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!
- // Define tgamma function with a no overflow policy
- // into a specific namespace-scope.
- #include <iostream>
- using std::cout; using std::endl;
- //[policy_ref_snip12
- #include <boost/math/special_functions/gamma.hpp>
- //using boost::math::tgamma;
- // Need not declare using boost::math::tgamma here,
- // because will define tgamma in myspace using macro below.
- namespace myspace
- {
- using namespace boost::math::policies;
- // Define a policy that does not throw on overflow:
- typedef policy<overflow_error<errno_on_error> > my_policy;
- // Define the special functions in this scope to use the policy:
- BOOST_MATH_DECLARE_SPECIAL_FUNCTIONS(my_policy)
- }
- // Now we can use myspace::tgamma etc.
- // They will automatically use "my_policy":
- //
- double t = myspace::tgamma(30.0); // Will *not* throw on overflow,
- // despite the large value of factorial 30 = 265252859812191058636308480000000
- // unlike default policy boost::math::tgamma;
- //]
- int main()
- {
- cout << "myspace::tgamma(30.0) = " << t << endl;
- }
- /*
- Output:
- myspace::tgamma(30.0) = 8.84176e+030
- */
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