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- // example_policy_handling.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)
- // 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.cpp 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 for double.
- using boost::math::policies::policy;
- using boost::math::policies::domain_error;
- using boost::math::policies::ignore_error;
- // std
- #include <iostream>
- using std::cout;
- using std::endl;
- #include <stdexcept>
-
- // Define a (bad?) policy to ignore domain errors ('bad' arguments):
- typedef policy<
- domain_error<ignore_error>
- > my_policy;
- // Define my_students_t 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.; // Two '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;
- // By contrast the students_t distribution default domain error policy is to throw,
- cout << cdf(students_t(-1), -1) << endl; // so this will throw.
- /*`
- 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 !
- */
- // We could also define a 'custom' distribution
- // with an "ignore overflow error policy" in a single statement:
- using boost::math::policies::overflow_error;
- students_t_distribution<double, policy<overflow_error<ignore_error> > > students_t_no_throw(-1);
- }
- catch(const std::exception& e)
- {
- std::cout <<
- "\n""Message from thrown exception was:\n " << e.what() << std::endl;
- }
- return 0;
- } // int main()
- /*
- Output:
- error_policy_example.cpp
- Generating code
- Finished generating code
- error_policy_example.vcxproj -> J:\Cpp\MathToolkit\test\Math_test\Release\error_policy_example.exe
- 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 !
- */
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