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| <div><h2 class="title"> |
| <a name="ratio"></a>Chapter 25. 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: April 07, 2015 at 22:51:15 GMT</small></p></td> |
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