Merge commit '4ebe6417a5fce5f0994fc0c31bebf732be96a07c' as 'boost'

boost/libs/math/example/c_error_policy_example.cpp

@@ -0,0 +1,83 @@
+// C_error_policy_example.cpp
+
+// Copyright Paul A. Bristow 2007, 2010.
+// Copyright John Maddock 2007.
+
+// 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)
+
+// Suppose we want a call to tgamma  to behave in a C-compatible way
+// and set global ::errno rather than throw an exception.
+
+#include <cerrno> // for ::errno
+
+#include <boost/math/special_functions/gamma.hpp>
+using boost::math::tgamma;
+
+using boost::math::policies::policy;
+// Possible errors
+using boost::math::policies::overflow_error;
+using boost::math::policies::underflow_error;
+using boost::math::policies::domain_error;
+using boost::math::policies::pole_error;
+using boost::math::policies::denorm_error;
+using boost::math::policies::evaluation_error;
+
+using boost::math::policies::errno_on_error;
+using boost::math::policies::ignore_error;
+
+//using namespace boost::math::policies;
+//using namespace boost::math; // avoid potential ambiuity with std:: <random>
+
+// Define a policy:
+typedef policy<
+      domain_error<errno_on_error>, // 'bad' arguments.
+      pole_error<errno_on_error>, // argument is pole value.
+      overflow_error<errno_on_error>, // argument value causes overflow.
+      evaluation_error<errno_on_error>  // evaluation does not converge and may be inaccurate, or worse,
+      // or there is no way  known (yet) to implement this evaluation,
+      // for example, kurtosis of non-central beta distribution.
+      > C_error_policy;
+
+// std
+#include <iostream>
+   using std::cout;
+   using std::endl;   
+
+int main()
+{
+  // We can achieve this at the function call site
+  // with the previously defined policy C_error_policy.
+  double t = tgamma(4., C_error_policy());
+  cout << "tgamma(4., C_error_policy() = " << t << endl; // 6
+
+  // Alternatively we could use the function make_policy,
+  // provided for convenience,
+  // and define everything at the call site:
+  t = tgamma(4., make_policy(
+         domain_error<errno_on_error>(), 
+         pole_error<errno_on_error>(),
+         overflow_error<errno_on_error>(),
+         evaluation_error<errno_on_error>() 
+      ));
+  cout << "tgamma(4., make_policy(...) = " << t << endl; // 6
+
+  return 0;
+} // int main()
+
+/*
+
+Output
+
+  c_error_policy_example.cpp
+  Generating code
+  Finished generating code
+  c_error_policy_example.vcxproj -> J:\Cpp\MathToolkit\test\Math_test\Release\c_error_policy_example.exe
+  tgamma(4., C_error_policy() = 6
+  tgamma(4., make_policy(...) = 6
+  tgamma(4., C_error_policy() = 6
+  tgamma(4., make_policy(...) = 6
+
+*/