[Boost-commit] svn:boost r38437 - sandbox/math_toolkit/libs/math/example

From: john_at_[hidden]
Date: 2007-08-04 04:55:59

Author: johnmaddock
Date: 2007-08-04 04:55:58 EDT (Sat, 04 Aug 2007)
New Revision: 38437
URL: http://svn.boost.org/trac/boost/changeset/38437

Log:
Initial commit, more tutorial examples.
Added:
   sandbox/math_toolkit/libs/math/example/policy_eg_6.cpp   (contents, props changed)
   sandbox/math_toolkit/libs/math/example/policy_eg_7.cpp   (contents, props changed)

Added: sandbox/math_toolkit/libs/math/example/policy_eg_6.cpp
==============================================================================
--- (empty file)
+++ sandbox/math_toolkit/libs/math/example/policy_eg_6.cpp	2007-08-04 04:55:58 EDT (Sat, 04 Aug 2007)
@@ -0,0 +1,119 @@
+//  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)
+
+// Note that this file contains quickbook markup as well as code
+// and comments, don't change any of the special comment markups!
+
+#include <iostream>
+
+//[policy_eg_6
+
+/*`
+Suppose we want a set of distributions to behave as follows:
+
+* Return infinity on overflow, rather than throwing an exception.
+* Don't perform any promotion from double to long double internally.
+* Return the closest integer result from the quantiles of discrete
+distributions.
+
+We'll begin by including the needed header:
+*/
+
+#include <boost/math/distributions.hpp>
+
+/*`
+
+Open up an appropriate namespace for our distrubtions, and
+define the policy type we want.  Any policies we don't
+specify here will inherit the defaults:
+
+*/
+
+namespace my_distributions{
+
+using namespace boost::math::policies;
+
+typedef policy<
+   // return infinity and set errno rather than throw:
+   overflow_error<errno_on_error>,
+   // Don't promote double -> long double internally:
+   promote_double<false>,
+   // Return the closest integer result for discrete quantiles:
+   discrete_quantile<integer_nearest>
+> my_policy;
+
+/*`
+
+All we need do now is invoke the BOOST_MATH_DECLARE_DISTRIBUTIONS
+macro passing the floating point and policy types as arguments:
+
+*/
+
+BOOST_MATH_DECLARE_DISTRIBUTIONS(double, my_policy)
+
+} // close namespace my_namespace
+
+/*`
+
+We now have a set of typedefs defined in namespace my_namespace
+that all look something like this:
+
+``
+typedef boost::math::normal_distribution<double, my_policy> normal;
+typedef boost::math::cauchy_distribution<double, my_policy> cauchy;
+typedef boost::math::gamma_distribution<double, my_policy> gamma;
+// etc
+``
+
+So that when we use my_namespace::normal we really end up using
+`boost::math::normal_distribution<double, my_policy>`:
+
+*/
+
+
+int main()
+{
+   //
+   // Start with something we know will overflow:
+   //
+   my_distributions::normal norm(10, 2);
+   errno = 0;
+   std::cout << "Result of quantile(norm, 0) is: " 
+      << quantile(norm, 0) << std::endl;
+   std::cout << "errno = " << errno << std::endl;
+   errno = 0;
+   std::cout << "Result of quantile(norm, 1) is: " 
+      << quantile(norm, 1) << std::endl;
+   std::cout << "errno = " << errno << std::endl;
+   //
+   // Now try a discrete distribution:
+   //
+   my_distributions::binomial binom(20, 0.25);
+   std::cout << "Result of quantile(binom, 0.05) is: " 
+      << quantile(binom, 0.05) << std::endl;
+   std::cout << "Result of quantile(complement(binom, 0.05)) is: " 
+      << quantile(complement(binom, 0.05)) << std::endl;
+}
+
+/*`
+
+Which outputs:
+
+[pre
+Result of quantile(norm, 0) is: -1.#INF
+errno = 34
+Result of quantile(norm, 1) is: 1.#INF
+errno = 34
+Result of quantile(binom, 0.05) is: 1
+Result of quantile(complement(binom, 0.05)) is: 8
+]
+
+This mechanism is particularly useful when we want to define a 
+project-wide policy, and don't want to modify the Boost source
+or set - possibly fragile and easy to forget - project wide 
+build macros.
+
+*/ //] ends quickbook imported section
+

Added: sandbox/math_toolkit/libs/math/example/policy_eg_7.cpp
==============================================================================
--- (empty file)
+++ sandbox/math_toolkit/libs/math/example/policy_eg_7.cpp	2007-08-04 04:55:58 EDT (Sat, 04 Aug 2007)
@@ -0,0 +1,75 @@
+//  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)
+
+// Note that this file contains quickbook markup as well as code
+// and comments, don't change any of the special comment markups!
+
+#include <iostream>
+
+//[policy_eg_7
+
+#include <boost/math/distributions.hpp>
+
+namespace {
+
+using namespace boost::math::policies;
+
+typedef policy<
+   // return infinity and set errno rather than throw:
+   overflow_error<errno_on_error>,
+   // Don't promote double -> long double internally:
+   promote_double<false>,
+   // Return the closest integer result for discrete quantiles:
+   discrete_quantile<integer_nearest>
+> my_policy;
+
+BOOST_MATH_DECLARE_DISTRIBUTIONS(double, my_policy)
+
+} // close namespace my_namespace
+
+int main()
+{
+   //
+   // Start with something we know will overflow:
+   //
+   normal norm(10, 2);
+   errno = 0;
+   std::cout << "Result of quantile(norm, 0) is: " 
+      << quantile(norm, 0) << std::endl;
+   std::cout << "errno = " << errno << std::endl;
+   errno = 0;
+   std::cout << "Result of quantile(norm, 1) is: " 
+      << quantile(norm, 1) << std::endl;
+   std::cout << "errno = " << errno << std::endl;
+   //
+   // Now try a discrete distribution:
+   //
+   binomial binom(20, 0.25);
+   std::cout << "Result of quantile(binom, 0.05) is: " 
+      << quantile(binom, 0.05) << std::endl;
+   std::cout << "Result of quantile(complement(binom, 0.05)) is: " 
+      << quantile(complement(binom, 0.05)) << std::endl;
+}
+
+/*`
+
+Which outputs:
+
+[pre
+Result of quantile(norm, 0) is: -1.#INF
+errno = 34
+Result of quantile(norm, 1) is: 1.#INF
+errno = 34
+Result of quantile(binom, 0.05) is: 1
+Result of quantile(complement(binom, 0.05)) is: 8
+]
+
+This mechanism is particularly useful when we want to define a 
+project-wide policy, and don't want to modify the Boost source
+or set - possibly fragile and easy to forget - project wide 
+build macros.
+
+*/ //] ends quickbook imported section
+