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e602f59025
Updated distribution docs to bring them into synch with the policy based code. Still a few "TODO" sections at present. [SVN r7545]
76 lines
2.4 KiB
Plaintext
76 lines
2.4 KiB
Plaintext
[section:error_eg Error Handling Example]
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TODO: this documentation is out of date, rewrite it!!
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See [link math_toolkit.special.error_handling error handling]
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for a detailed explanation of the mechanism of handling errors,
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including the common "bad" arguments to distributions and functions.
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But, by default, *none of these exceptions will be raised*,
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and the most appropriate value, usually a NaN, or zero, will be returned.
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So, for example, without any attempt to deal with errors, if we write
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cout << "Probability of Student's t is "
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<< boost::math::cdf(students_t(-1), -1) << endl;
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the output will be:
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Probability of Student's t is 1.#QNAN
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However, macros control whether an exception is raised, or not,
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for the following errors:
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BOOST_MATH_THROW_ON_DOMAIN_ERROR
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BOOST_MATH_THROW_ON_OVERFLOW_ERROR
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BOOST_MATH_THROW_ON_OVERFLOW_ERROR
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BOOST_MATH_THROW_ON_UNDERFLOW_ERROR
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BOOST_MATH_THROW_ON_DENORM_ERROR
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BOOST_MATH_THROW_ON_LOGIC_ERROR
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[important These #defines *MUST* be *BEFORE* the function or distribution #include!]
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If defined, for example with
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#define BOOST_MATH_THROW_ON_DOMAIN_ERROR
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before
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#include <boost/math/distributions/students_t.hpp>
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then a domain_error exception will throw if we write
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try
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{
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cout << "Probability of Student's t is "
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<< boost::math::cdf(students_t(-1), -1) << endl; // Bad arguments!
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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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and will output:
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Message from thrown exception was:
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Error in function __thiscall
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boost::math::students_t_distribution<double>::students_t_distribution(double):
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Degrees of freedom argument is -1, but must be > 0 !
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See [@../../example/error_handling_example.cpp error_handling_example.cpp]
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[caution If you enable throw but do NOT have try & catch block,
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then the program will terminate with an uncaught exception and probably abort.
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Therefore to get the benefit of helpful error messages, enabling *all exceptions
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and using try & catch* is recommended for all applications.
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However, for simplicity, the is not done for most examples.]
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[endsect] [/section:error_eg Error Handling Example]
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[/
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Copyright 2006 John Maddock and Paul A. Bristow.
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE_1_0.txt or copy at
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http://www.boost.org/LICENSE_1_0.txt).
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]
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