boost-react-native-bundle

<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Extras/Future Directions</title> <link rel="stylesheet" href="../math.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="../index.html" title="Math Toolkit 2.1.0"> <link rel="up" href="../dist.html" title="Chapter 5. Statistical Distributions and Functions"> <link rel="prev" href="dist_ref/dist_algorithms.html" title="Distribution Algorithms"> <link rel="next" href="../special.html" title="Chapter 6. Special Functions"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../boost.png"></td> <td align="center"><a href="../../../../../index.html">Home</a></td> <td align="center"><a href="../../../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../../../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="dist_ref/dist_algorithms.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../dist.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../special.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="section"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="math_toolkit.future"></a><a class="link" href="future.html" title="Extras/Future Directions">Extras/Future Directions</a> </h2></div></div></div> <h5> <a name="math_toolkit.future.h0"></a> <a name="math_toolkit.future.adding_additional_location_and_s"></a><a class="link" href="future.html#math_toolkit.future.adding_additional_location_and_s">Adding Additional Location and Scale Parameters</a> </h5> In some modelling applications we require a distribution with a specific location and scale: often this equates to a specific mean and standard deviation, although for many distributions the relationship between these properties and the location and scale parameters are non-trivial. See <a href="http://www.itl.nist.gov/div898/handbook/eda/section3/eda364.htm" target="_top">http://www.itl.nist.gov/div898/handbook/eda/section3/eda364.htm</a> for more information. The obvious way to handle this is via an adapter template: <pre class="programlisting">template <class Dist> class scaled_distribution { scaled_distribution( const Dist dist, typename Dist::value_type location, typename Dist::value_type scale = 0); }; </pre> Which would then have its own set of overloads for the non-member accessor functions. <h5> <a name="math_toolkit.future.h1"></a> <a name="math_toolkit.future.an_any_distribution_class"></a><a class="link" href="future.html#math_toolkit.future.an_any_distribution_class">An "any_distribution" class</a> </h5> It is easy to add a distribution object that virtualises the actual type of the distribution, and can therefore hold "any" object that conforms to the conceptual requirements of a distribution: <pre class="programlisting">template <class RealType> class any_distribution { public: template <class Distribution> any_distribution(const Distribution& d); }; // Get the cdf of the underlying distribution: template <class RealType> RealType cdf(const any_distribution<RealType>& d, RealType x); // etc.... </pre> Such a class would facilitate the writing of non-template code that can function with any distribution type. The <a href="http://sourceforge.net/projects/distexplorer/" target="_top">Statistical Distribution Explorer</a> utility for Windows is a usage example. It's not clear yet whether there is a compelling use case though. Possibly tests for goodness of fit might provide such a use case: this needs more investigation. <h5> <a name="math_toolkit.future.h2"></a> <a name="math_toolkit.future.higher_level_hypothesis_tests"></a><a class="link" href="future.html#math_toolkit.future.higher_level_hypothesis_tests">Higher Level Hypothesis Tests</a> </h5> Higher-level tests roughly corresponding to the <a href="http://documents.wolfram.com/mathematica/Add-onsLinks/StandardPackages/Statistics/HypothesisTests.html" target="_top">Mathematica Hypothesis Tests</a> package could be added reasonably easily, for example: <pre class="programlisting">template <class InputIterator> typename std::iterator_traits<InputIterator>::value_type test_equal_mean( InputIterator a, InputIterator b, typename std::iterator_traits<InputIterator>::value_type expected_mean); </pre> Returns the probability that the data in the sequence [a,b) has the mean expected_mean. <h5> <a name="math_toolkit.future.h3"></a> <a name="math_toolkit.future.integration_with_statistical_acc"></a><a class="link" href="future.html#math_toolkit.future.integration_with_statistical_acc">Integration With Statistical Accumulators</a> </h5> <a href="http://boost-sandbox.sourceforge.net/libs/accumulators/doc/html/index.html" target="_top">Eric Niebler's accumulator framework</a> - also work in progress - provides the means to calculate various statistical properties from experimental data. There is an opportunity to integrate the statistical tests with this framework at some later date: <pre class="programlisting">// Define an accumulator, all required statistics to calculate the test // are calculated automatically: accumulator_set<double, features<tag::test_expected_mean> > acc(expected_mean=4); // Pass our data to the accumulator: acc = std::for_each(mydata.begin(), mydata.end(), acc); // Extract the result: double p = probability(acc); </pre> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 2006-2010, 2012-2014 Nikhar Agrawal, Anton Bikineev, Paul A. Bristow, Marco Guazzone, Christopher Kormanyos, Hubert Holin, Bruno Lalande, John Maddock, Johan Råde, Gautam Sewani, Benjamin Sobotta, Thijs van den Berg, Daryle Walker and Xiaogang Zhang Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="dist_ref/dist_algorithms.html"><img src="../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../dist.html"><img src="../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../special.html"><img src="../../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>