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Added another example to the policy tutorial.
Fixed \n warnings in the issue list. Suppressed some Intel compiler messages. [SVN r38445]
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John Maddock
@@ -37,20 +37,22 @@ basic arithmetic operations. Maybe this is telling us something, or maybe not
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[h4 Elliptic Integrals]
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[template para[text] '''<para>'''[text]'''</para>''']
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* Carlson's algorithms are essentially unchanged from Xiaogang Zhang's
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Google Summer of Code student project, and are based on Carlson's
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original papers. However, Carlson has revised his algorithms since then
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(refer to the references in the elliptic integral docs for a list), to
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improve performance and accuracy, we may be able to take advantage
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of these improvements too (Low Priority).
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* Carlson's algorithms (mainly R[sub J]) are somewhat prone to
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* [para Carlson's algorithms (mainly R[sub J]) are somewhat prone to
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internal overflow/underflow when the arguments are very large or small.
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The homogeneity relations: \n
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R[sub F](ka, kb, kc) = k[super -1/2] R[sub F](a, b, c)\n
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and\n
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R[sub J](ka, kb, kc, kr) = k[super -3/2] R[sub J](a, b, c, r)\n
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could be used to sidestep trouble here: provided the problem domains
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can be accurately identified. (Medium Priority).
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The homogeneity relations:]
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[para R[sub F](ka, kb, kc) = k[super -1/2] R[sub F](a, b, c)]
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[para and]
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[para R[sub J](ka, kb, kc, kr) = k[super -3/2] R[sub J](a, b, c, r)]
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[para could be used to sidestep trouble here: provided the problem domains
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can be accurately identified. (Medium Priority).]
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* Carlson's R[sub C] can be reduced to elementary funtions (asin and log),
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would it be more efficient evaluated this way, rather than by Carlson's
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algorithms? (Low Priority).
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@@ -152,6 +152,10 @@ And, yes, you will find examples in our test programs where we break this
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rule: but only because we know there will always be a single
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translation unit only: don't say that you weren't warned!
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[import ../example/error_handling_example.cpp]
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[error_handling_example]
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[heading Setting Policies for Distributions on an Ad Hoc Basis]
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All of the statistical distributions in this library are class templates
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@@ -1,25 +1,51 @@
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// example_error_handling.cpp
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// Copyright Paul A. Bristow 2007.
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// Copyright John Maddock 2006.
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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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// Shows use of 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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// Note that this file contains quickbook markup as well as code
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// and comments, don't change any of the special comment markups!
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// Uncomment this line to see the effect of changing policy,
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// to ignore the error & return NaN instead of throwing an exception.
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// #define BOOST_MATH_DOMAIN_ERROR_POLICY ignore_error
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// Note that these policy #defines MUST preceed the #include of
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// any boost/math #includes.
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// If placed after, they will have no effect!
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// warning C4005: 'BOOST_MATH_OVERFLOW_ERROR_POLICY' : macro redefinition
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// is a warning that it will NOT have the desired effect.
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//[error_handling_example
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/*`
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The following example demonstrates the effect of
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setting the macro BOOST_MATH_DOMAIN_ERROR_POLICY
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when an invalid argument is encountered. For the
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purposes of this example we'll pass a negative
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degrees of freedom parameter to the student's t
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distribution.
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Since we know that this is a single file program we could
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just add:
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#define BOOST_MATH_DOMAIN_ERROR_POLICY ignore_error
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to the top of the source file to change the default policy
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to one that simply returns a NaN when a domain error occurs.
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Alternatively we could use:
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#define BOOST_MATH_DOMAIN_ERROR_POLICY errno_on_error
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To ensure the `::errno` is set when a domain error occurs
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as well as returning a NaN.
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This is safe provided the program consists of a single
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translation unit /and/ we place the define /before/ any
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#includes. Note that should we add the define after the includes
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then it will have no effect! A warning such as:
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[pre warning C4005: 'BOOST_MATH_OVERFLOW_ERROR_POLICY' : macro redefinition]
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is a certain sign that it will /not/ have the desired effect.
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We'll begin our sample program with the needed includes:
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*/
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// Boost
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#include <boost/math/distributions/students_t.hpp>
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@@ -33,47 +59,85 @@
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#include <stdexcept>
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using std::exception;
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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.; // Bad arguments!
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// If we use
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// cout << "Probability of Student's t is " << cdf(students_t(-1), -1) << endl;
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// Will terminate/abort (without try & catch blocks)
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// if BOOST_MATH_DOMAIN_ERROR_POLICY has the default value throw_on_error.
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try
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{
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cout << "Probability of Student's t is " << cdf(students_t(degrees_of_freedom), t) << endl;
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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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Example error handling using Student's t function.
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With
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#define BOOST_MATH_DOMAIN_ERROR_POLICY ignore_error
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Example error handling using Student's t function.
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Probability of Student's t is 1.#QNAN
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Default behaviour without:
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Example error handling using Student's t function.
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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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Next we'll define the program's main() to call the student's t
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distribution with an invalid degrees of freedom parameter, the program
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is set up to handle either an exception or a NaN:
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*/
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int main()
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{
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cout << "Example error handling using Student's t function. " << endl;
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cout << "BOOST_MATH_DOMAIN_ERROR_POLICY is set to: "
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<< BOOST_STRINGIZE(BOOST_MATH_DOMAIN_ERROR_POLICY) << endl;
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double degrees_of_freedom = -1; // A bad argument!
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double t = 10;
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try
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{
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errno = 0;
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students_t dist(degrees_of_freedom); // exception is thrown here if enabled
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double p = cdf(dist, t);
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// test for error reported by other means:
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if((boost::math::isnan)(p))
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{
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cout << "cdf returned a NaN!" << endl;
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cout << "errno is set to: " << errno << endl;
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}
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else
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cout << "Probability of Student's t is " << p << endl;
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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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Here's what the program output looks like with a default build
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(one that does throw exceptions):
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[pre
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Example error handling using Student's t function.
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BOOST_MATH_DOMAIN_ERROR_POLICY is set to: throw_on_error
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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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Alternatively let's build with:
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#define BOOST_MATH_DOMAIN_ERROR_POLICY ignore_error
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Now the program output is:
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[pre
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Example error handling using Student's t function.
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BOOST_MATH_DOMAIN_ERROR_POLICY is set to: ignore_error
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cdf returned a NaN!
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errno is set to: 0
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]
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And finally let's build with:
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#define BOOST_MATH_DOMAIN_ERROR_POLICY errno_on_error
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Which gives the output:
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[pre
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Example error handling using Student's t function.
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BOOST_MATH_DOMAIN_ERROR_POLICY is set to: errno_on_error
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cdf returned a NaN!
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errno is set to: 33
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]
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*/
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//] end quickbook markup
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@@ -13,6 +13,8 @@ project
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<toolset>darwin:<cxxflags>-Wno-missing-braces
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<toolset>acc:<cxxflags>+W2068,2461,2236,4070
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<toolset>intel:<cxxflags>-Qwd264,239
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<toolset>intel:<cxxflags>/nologo
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<toolset>intel:<linkflags>/nologo
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<toolset>msvc:<warnings>all
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<toolset>msvc:<asynch-exceptions>on
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<toolset>msvc:<cxxflags>/wd4996
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@@ -183,3 +185,5 @@ compile compile_test/tools_toms748_solve_inc_test.cpp ;
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