<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Chapter 26. Boost.Ratio 2.1.0</title> <link rel="stylesheet" href="../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="libraries.html" title="Part I. The Boost C++ Libraries (BoostBook Subset)"> <link rel="prev" href="boost_random/history_and_acknowledgements.html" title="History and Acknowledgements"> <link rel="next" href="ratio/users_guide.html" title="User's Guide"> </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="boost_random/history_and_acknowledgements.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="libraries.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="ratio/users_guide.html"><img src="../../doc/src/images/next.png" alt="Next"></a> </div> <div class="chapter"> <div class="titlepage"><div> <div><h2 class="title"> <a name="ratio"></a>Chapter 26. Boost.Ratio 2.1.0</h2></div> <div><div class="author"><h3 class="author"> <span class="firstname">Howard</span> <span class="surname">Hinnant</span> </h3></div></div> <div><div class="author"><h3 class="author"> <span class="firstname">Beman</span> <span class="surname">Dawes</span> </h3></div></div> <div><div class="author"><h3 class="author"> <span class="firstname">Vicente J.</span> <span class="surname">Botet Escriba</span> </h3></div></div> <div><p class="copyright">Copyright © 2008 Howard Hinnant</p></div> <div><p class="copyright">Copyright © 2006, 2008 Beman Dawes</p></div> <div><p class="copyright">Copyright © 2009-2012 Vicente J. Botet Escriba</p></div> <div><div class="legalnotice"> <a name="ratio.legal"></a><p> 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>) </p> </div></div> </div></div> <div class="toc"> <p><b>Table of Contents</b></p> <dl class="toc"> <dt><span class="section"><a href="ratio.html#ratio.overview">Overview</a></span></dt> <dd><dl> <dt><span class="section"><a href="ratio.html#ratio.overview.motivation">Motivation</a></span></dt> <dt><span class="section"><a href="ratio.html#ratio.overview.description">Description</a></span></dt> </dl></dd> <dt><span class="section"><a href="ratio/users_guide.html">User's Guide</a></span></dt> <dd><dl> <dt><span class="section"><a href="ratio/users_guide.html#ratio.users_guide.getting_started">Getting Started</a></span></dt> <dt><span class="section"><a href="ratio/users_guide.html#ratio.users_guide.tutorial">Tutorial</a></span></dt> <dt><span class="section"><a href="ratio/users_guide.html#ratio.users_guide.Examples">Example</a></span></dt> <dt><span class="section"><a href="ratio/users_guide.html#ratio.users_guide.ext_references">External Resources</a></span></dt> </dl></dd> <dt><span class="section"><a href="ratio/reference.html">Reference </a></span></dt> <dd><dl> <dt><span class="section"><a href="ratio/reference.html#ratio.reference.config_hpp">Header <code class="computeroutput"><span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">ratio</span><span class="special">/</span><span class="identifier">config</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code></a></span></dt> <dt><span class="section"><a href="ratio/reference.html#ratio.reference.std">C++0x Recommendation</a></span></dt> <dt><span class="section"><a href="ratio/reference.html#ratio.reference.io">Ratio I/O</a></span></dt> <dt><span class="section"><a href="ratio/reference.html#ratio.reference.mpl">Rational Constant</a></span></dt> </dl></dd> <dt><span class="section"><a href="ratio/appendices.html">Appendices</a></span></dt> <dd><dl> <dt><span class="section"><a href="ratio/appendices.html#ratio.appendices.history">Appendix A: History</a></span></dt> <dt><span class="section"><a href="ratio/appendices.html#ratio.appendices.rationale">Appendix B: Rationale</a></span></dt> <dt><span class="section"><a href="ratio/appendices.html#ratio.appendices.implementation">Appendix C: Implementation Notes</a></span></dt> <dt><span class="section"><a href="ratio/appendices.html#ratio.appendices.faq">Appendix D: FAQ</a></span></dt> <dt><span class="section"><a href="ratio/appendices.html#ratio.appendices.acknowledgements">Appendix E: Acknowledgements</a></span></dt> <dt><span class="section"><a href="ratio/appendices.html#ratio.appendices.tests">Appendix F: Tests</a></span></dt> <dt><span class="section"><a href="ratio/appendices.html#ratio.appendices.tickets">Appendix G: Tickets</a></span></dt> <dt><span class="section"><a href="ratio/appendices.html#ratio.appendices.todo">Appendix H: Future Plans</a></span></dt> </dl></dd> </dl> </div> <div class="section"> <div class="titlepage"><div><div><h2 class="title" style="clear: both"> <a name="ratio.overview"></a><a class="link" href="ratio.html#ratio.overview" title="Overview">Overview</a> </h2></div></div></div> <div class="toc"><dl class="toc"> <dt><span class="section"><a href="ratio.html#ratio.overview.motivation">Motivation</a></span></dt> <dt><span class="section"><a href="ratio.html#ratio.overview.description">Description</a></span></dt> </dl></div> <h4> <a name="ratio.overview.h0"></a> <span class="phrase"><a name="ratio.overview.how_to_use_this_documentation"></a></span><a class="link" href="ratio.html#ratio.overview.how_to_use_this_documentation">How to Use This Documentation</a> </h4> <p> This documentation makes use of the following naming and formatting conventions. </p> <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> Code is in <code class="computeroutput"><span class="identifier">fixed</span> <span class="identifier">width</span> <span class="identifier">font</span></code> and is syntax-highlighted. </li> <li class="listitem"> Replaceable text that you will need to supply is in <em class="replaceable"><code>italics</code></em>. </li> <li class="listitem"> Free functions are rendered in the code font followed by <code class="computeroutput"><span class="special">()</span></code>, as in <code class="computeroutput"><span class="identifier">free_function</span><span class="special">()</span></code>. </li> <li class="listitem"> If a name refers to a class template, it is specified like this: <code class="computeroutput"><span class="identifier">class_template</span><span class="special"><></span></code>; that is, it is in code font and its name is followed by <code class="computeroutput"><span class="special"><></span></code> to indicate that it is a class template. </li> <li class="listitem"> If a name refers to a function-like macro, it is specified like this: <code class="computeroutput"><span class="identifier">MACRO</span><span class="special">()</span></code>; that is, it is uppercase in code font and its name is followed by <code class="computeroutput"><span class="special">()</span></code> to indicate that it is a function-like macro. Object-like macros appear without the trailing <code class="computeroutput"><span class="special">()</span></code>. </li> <li class="listitem"> Names that refer to <span class="emphasis"><em>concepts</em></span> in the generic programming sense are specified in CamelCase. </li> </ul></div> <div class="note"><table border="0" summary="Note"> <tr> <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../doc/src/images/note.png"></td> <th align="left">Note</th> </tr> <tr><td align="left" valign="top"><p> In addition, notes such as this one specify non-essential information that provides additional background or rationale. </p></td></tr> </table></div> <p> Finally, you can mentally add the following to any code fragments in this document: </p> <pre class="programlisting"><span class="comment">// Include all of Ratio files</span> <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">ratio</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">;</span> </pre> <div class="section"> <div class="titlepage"><div><div><h3 class="title"> <a name="ratio.overview.motivation"></a><a class="link" href="ratio.html#ratio.overview.motivation" title="Motivation">Motivation</a> </h3></div></div></div> <p> <span class="bold"><strong>Boost.Ratio</strong></span> aims to implement the compile time ratio facility in C++0x, as proposed in <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2661.htm" target="_top"><span class="bold"><strong>N2661 - A Foundation to Sleep On</strong></span></a>. That document provides background and motivation for key design decisions and is the source of a good deal of information in this documentation. </p> </div> <div class="section"> <div class="titlepage"><div><div><h3 class="title"> <a name="ratio.overview.description"></a><a class="link" href="ratio.html#ratio.overview.description" title="Description">Description</a> </h3></div></div></div> <p> The <span class="bold"><strong>Boost.Ratio</strong></span> library provides: </p> <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> <li class="listitem"> A class template, <a class="link" href="ratio/reference.html#ratio.reference.std.ratio_hpp.ratio" title="Class Template ratio<>"><code class="computeroutput"><span class="identifier">ratio</span></code></a>, for specifying compile time rational constants such as 1/3 of a nanosecond or the number of inches per meter. <a class="link" href="ratio/reference.html#ratio.reference.std.ratio_hpp.ratio" title="Class Template ratio<>"><code class="computeroutput"><span class="identifier">ratio</span></code></a> represents a compile time ratio of compile time constants with support for compile time arithmetic with overflow and division by zero protection. </li> <li class="listitem"> It provides a textual representation of <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">ratio</span><span class="special"><</span><span class="identifier">N</span><span class="special">,</span> <span class="identifier">D</span><span class="special">></span></code> in the form of a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">basic_string</span></code> which can be useful for I/O. </li> <li class="listitem"> Some extension related to the <a class="link" href="ratio/reference.html#ratio.reference.mpl.rational_constant" title="Rational Constant Concept">Rational Constant</a> concept enabling the use of <a class="link" href="ratio/reference.html#ratio.reference.std.ratio_hpp.ratio" title="Class Template ratio<>"><code class="computeroutput"><span class="identifier">ratio</span></code></a><> in the context of <span class="bold"><strong>Boost.MPL</strong></span> numeric metafunctions. </li> </ul></div> </div> </div> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"><p><small>Last revised: December 14, 2015 at 09:19:35 GMT</small></p></td> <td align="right"><div class="copyright-footer"></div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="boost_random/history_and_acknowledgements.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="libraries.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="ratio/users_guide.html"><img src="../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>