<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Finding the Next Smaller Representable Value (float_prior)</title> <link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.74.0"> <link rel="home" href="../../../index.html" title="Math Toolkit"> <link rel="up" href="../next_float.html" title="Floating-Point Representation Distance (ULP), and Finding Adjacent Floating-Point Values"> <link rel="prev" href="float_next.html" title="Finding the Next Greater Representable Value (float_next)"> <link rel="next" href="float_distance.html" title="Calculating the Representation Distance Between Two Floating Point Values (ULP) float_distance"> </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="float_next.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../next_float.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="float_distance.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="section" lang="en"> <div class="titlepage"><div><div><h4 class="title"> <a name="math_toolkit.utils.next_float.float_prior"></a><a class="link" href="float_prior.html" title="Finding the Next Smaller Representable Value (float_prior)"> Finding the Next Smaller Representable Value (float_prior)</a> </h4></div></div></div> <a name="math_toolkit.utils.next_float.float_prior.synopsis"></a><h5> <a name="id1165017"></a> <a class="link" href="float_prior.html#math_toolkit.utils.next_float.float_prior.synopsis">Synopsis</a> </h5> <p> </p> <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">special_functions</span><span class="special">/</span><span class="identifier">next</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> </pre> <p> </p> <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">math</span><span class="special">{</span> <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">FPT</span><span class="special">></span> <span class="identifier">FPT</span> <span class="identifier">float_prior</span><span class="special">(</span><span class="identifier">FPT</span> <span class="identifier">val</span><span class="special">);</span> <span class="special">}}</span> <span class="comment">// namespaces </span></pre> <a name="math_toolkit.utils.next_float.float_prior.description___float_prior"></a><h5> <a name="id1165169"></a> <a class="link" href="float_prior.html#math_toolkit.utils.next_float.float_prior.description___float_prior">Description - float_prior</a> </h5> <p> Returns the next representable value which is less than <span class="emphasis"><em>x</em></span>. If <span class="emphasis"><em>x</em></span> is non-finite then returns the result of a <a class="link" href="../../main_overview/error_handling.html#domain_error">domain_error</a>. If there is no such value less than <span class="emphasis"><em>x</em></span> then returns an <a class="link" href="../../main_overview/error_handling.html#overflow_error">overflow_error</a>. </p> <p> Has the same effect as </p> <pre class="programlisting"><span class="identifier">nextafter</span><span class="special">(</span><span class="identifier">val</span><span class="special">,</span> <span class="special">-</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">numeric_limits</span><span class="special"><</span><span class="identifier">FPT</span><span class="special">>::</span><span class="identifier">max</span><span class="special">());</span> <span class="comment">// Note most negative value -max. </span></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 , 2007, 2008, 2009 John Maddock, Paul A. Bristow, Hubert Holin, Xiaogang Zhang, Bruno Lalande, Johan Råde, Gautam Sewani and Thijs van den Berg<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></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="float_next.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../next_float.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="float_distance.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>