Initial commit

libs/math/example/policy_eg_5.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)
+
+// 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 <iostream>
+using std::cout;  using std::endl;
+#include <cerrno> // for ::errno
+
+//[policy_eg_5
+
+#include <boost/math/special_functions.hpp>
+// using boost::math::tgamma; // Would create an ambiguity between
+// 'double boost::math::tgamma<int>(T)' and
+// 'double 'anonymous-namespace'::tgamma<int>(RT)'.
+
+namespace mymath
+{ // unnamed
+
+using namespace boost::math::policies;
+
+typedef policy<
+   domain_error<errno_on_error>,
+   pole_error<errno_on_error>,
+   overflow_error<errno_on_error>,
+   evaluation_error<errno_on_error>
+> c_policy;
+
+BOOST_MATH_DECLARE_SPECIAL_FUNCTIONS(c_policy)
+
+/*`
+So that when we call `mymath::tgamma(z)`, we really end up calling
+ `boost::math::tgamma(z, anonymous-namespace::c_policy())`.
+*/
+
+} // close unnamed namespace
+
+int main()
+{
+   errno = 0;
+   cout << "Result of tgamma(30000) is: "
+      << mymath::tgamma(30000) << endl;
+      // tgamma in unnamed namespace in this translation unit (file) only.
+   cout << "errno = " << errno << endl;
+   cout << "Result of tgamma(-10) is: "
+      << mymath::tgamma(-10) << endl;
+   cout << "errno = " << errno << endl;
+   // Default tgamma policy would throw an exception, and abort.
+}
+
+//] //[/policy_eg_5]
+
+/*
+Output:
+
+  Result of tgamma(30000) is: 1.#INF
+  errno = 34
+  Result of tgamma(-10) is: 1.#QNAN
+  errno = 33
+
+
+*/