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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!
#include <boost/config.hpp>
#ifdef _MSC_VER
# pragma warning (disable : 4189) // 'd' : local variable is initialized but not referenced
#endif
#ifdef BOOST_GCC
# pragma GCC diagnostic ignored "-Wunused-variable"
#endif
#include <iostream>
using std::cout; using std::endl;
#include <stdexcept>
using std::domain_error;
//[policy_ref_snip13
#include <boost/math/distributions/cauchy.hpp>
namespace myspace
{ // using namespace boost::math::policies; // May be convenient in myspace.
// Define a policy called my_policy to use.
using boost::math::policies::policy;
// In this case we want all the distribution accessor functions to compile,
// even if they are mathematically undefined, so
// make the policy assert_undefined.
using boost::math::policies::assert_undefined;
typedef policy<assert_undefined<false> > my_policy;
// Finally apply this policy to type double.
BOOST_MATH_DECLARE_DISTRIBUTIONS(double, my_policy)
} // namespace myspace
// Now we can use myspace::cauchy etc, which will use policy
// myspace::mypolicy:
//
// This compiles but throws a domain error exception at runtime.
// Caution! If you omit the try'n'catch blocks,
// it will just silently terminate, giving no clues as to why!
// So try'n'catch blocks are very strongly recommended.
void test_cauchy()
{
try
{
double d = mean(myspace::cauchy()); // Cauchy does not have a mean!
(void) d;
}
catch(const std::domain_error& e)
{
cout << e.what() << endl;
}
}
//] //[/policy_ref_snip13]
int main()
{
test_cauchy();
}
/*
Output:
policy_snip_13.vcxproj -> J:\Cpp\MathToolkit\test\Math_test\Release\policy_snip_13.exe
Error in function boost::math::mean(cauchy<double>&): The Cauchy distribution does not have a mean: the only possible return value is 1.#QNAN.
*/
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