Further examples

[SVN r7586]

example/error_policy_example.cpp

@@ -0,0 +1,76 @@
+// example_policy_handling.cpp
+
+// Copyright Paul A. Bristow 2007.
+// 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)
+
+// See error_handling_example.cpp for use of
+// macro definition to change policy for
+// domain_error - negative degrees of freedom argument
+// for student's t distribution CDF,
+// and catching the exception.
+
+// See error_handling_policies for more examples.
+
+// Boost
+#include <boost/math/distributions/students_t.hpp>
+using boost::math::students_t_distribution;  // Probability of students_t(df, t).
+using boost::math::students_t;  // Probability of students_t(df, t) convenience typedef.
+
+// std
+#include <iostream>
+	using std::cout;
+	using std::endl;
+
+#include <stdexcept>
+	using std::exception;
+
+using boost::math::policy::policy;
+using boost::math::policy::domain_error;
+using boost::math::policy::ignore_error;
+
+// Define a (bad?) policy to ignore domain errors ('bad' arguments):
+typedef policy<
+      domain_error<ignore_error>
+      > my_policy;
+
+// Define my distribution with this different domain error policy:
+typedef students_t_distribution<double, my_policy> my_students_t;
+
+int main()
+{  // Example of error handling of bad argument(s) to a distribution.
+	cout << "Example error handling using Student's t function. " << endl;
+
+  double degrees_of_freedom = -1; double t = -1.; // Bad arguments!
+
+  try
+  {
+    cout << "Probability of ignore_error Student's t is " << cdf(my_students_t(degrees_of_freedom), t) << endl;
+    cout << "Probability of default error policy Student's t is " << endl;
+    cout << cdf(students_t(-1), -1) << endl;
+  }
+  catch(const std::exception& e)
+  {
+    std::cout <<
+      "\n""Message from thrown exception was:\n   " << e.what() << std::endl;
+  }
+
+	return 0;
+} // int main()
+
+/*
+
+Output:
+
+Example error handling using Student's t function. 
+Probability of ignore_error Student's t is 1.#QNAN
+Probability of default error policy Student's t is 
+Message from thrown exception was:
+   Error in function boost::math::students_t_distribution<double>::students_t_distribution:
+   Degrees of freedom argument is -1, but must be > 0 !
+
+*/