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94 lines
3.0 KiB
C++
94 lines
3.0 KiB
C++
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// example_policy_handling.cpp
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// Copyright Paul A. Bristow 2007, 2010.
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// Copyright John Maddock 2007.
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt
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// or copy at http://www.boost.org/LICENSE_1_0.txt)
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// See error_handling_example.cpp for use of
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// macro definition to change policy for
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// domain_error - negative degrees of freedom argument
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// for student's t distribution CDF,
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// and catching the exception.
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// See error_handling_policies.cpp for more examples.
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// Boost
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#include <boost/math/distributions/students_t.hpp>
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using boost::math::students_t_distribution; // Probability of students_t(df, t).
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using boost::math::students_t; // Probability of students_t(df, t) convenience typedef for double.
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using boost::math::policies::policy;
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using boost::math::policies::domain_error;
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using boost::math::policies::ignore_error;
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// std
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#include <iostream>
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using std::cout;
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using std::endl;
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#include <stdexcept>
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// Define a (bad?) policy to ignore domain errors ('bad' arguments):
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typedef policy<
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domain_error<ignore_error>
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> my_policy;
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// Define my_students_t distribution with this different domain error policy:
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typedef students_t_distribution<double, my_policy> my_students_t;
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int main()
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{ // Example of error handling of bad argument(s) to a distribution.
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cout << "Example error handling using Student's t function. " << endl;
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double degrees_of_freedom = -1; double t = -1.; // Two 'bad' arguments!
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try
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{
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cout << "Probability of ignore_error Student's t is "
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<< cdf(my_students_t(degrees_of_freedom), t) << endl;
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cout << "Probability of default error policy Student's t is " << endl;
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// By contrast the students_t distribution default domain error policy is to throw,
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cout << cdf(students_t(-1), -1) << endl; // so this will throw.
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/*`
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Message from thrown exception was:
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Error in function boost::math::students_t_distribution<double>::students_t_distribution:
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Degrees of freedom argument is -1, but must be > 0 !
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*/
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// We could also define a 'custom' distribution
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// with an "ignore overflow error policy" in a single statement:
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using boost::math::policies::overflow_error;
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students_t_distribution<double, policy<overflow_error<ignore_error> > > students_t_no_throw(-1);
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}
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catch(const std::exception& e)
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{
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std::cout <<
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"\n""Message from thrown exception was:\n " << e.what() << std::endl;
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}
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return 0;
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} // int main()
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/*
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Output:
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error_policy_example.cpp
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Generating code
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Finished generating code
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error_policy_example.vcxproj -> J:\Cpp\MathToolkit\test\Math_test\Release\error_policy_example.exe
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Example error handling using Student's t function.
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Probability of ignore_error Student's t is 1.#QNAN
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Probability of default error policy Student's t is
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Message from thrown exception was:
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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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*/
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