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| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="math_toolkit.utils.next_float.nextafter"></a><a class="link" href="nextafter.html" title="Finding the Next Representable Value in a Specific Direction (nextafter)"> Finding the |
| Next Representable Value in a Specific Direction (nextafter)</a> |
| </h4></div></div></div> |
| <a name="math_toolkit.utils.next_float.nextafter.synopsis"></a><h5> |
| <a name="id1160603"></a> |
| <a class="link" href="nextafter.html#math_toolkit.utils.next_float.nextafter.synopsis">Synopsis</a> |
| </h5> |
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| |
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| <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">nextafter</span><span class="special">(</span><span class="identifier">FPT</span> <span class="identifier">val</span><span class="special">,</span> <span class="identifier">FPT</span> <span class="identifier">direction</span><span class="special">);</span> |
| |
| <span class="special">}}</span> <span class="comment">// namespaces |
| </span></pre> |
| <a name="math_toolkit.utils.next_float.nextafter.description___nextafter"></a><h5> |
| <a name="id1160769"></a> |
| <a class="link" href="nextafter.html#math_toolkit.utils.next_float.nextafter.description___nextafter">Description |
| - nextafter</a> |
| </h5> |
| <p> |
| This is an implementation of the <code class="computeroutput"><span class="identifier">nextafter</span></code> |
| function included in the C99 standard. (It is also effectively an implementation |
| of the C99 'nexttoward' legacy function which differs only having a long |
| double direction, and can generally serve in its place if required). |
| </p> |
| <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> |
| The C99 functions must use suffixes f and l to distinguish float and |
| long double versions. C++ uses the template mechanism instead. |
| </p></td></tr> |
| </table></div> |
| <p> |
| Returns the next representable value after <span class="emphasis"><em>x</em></span> in the |
| direction of <span class="emphasis"><em>y</em></span>. If <code class="computeroutput"><span class="identifier">x</span> |
| <span class="special">==</span> <span class="identifier">y</span></code> |
| then returns <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 in the direction of <span class="emphasis"><em>y</em></span> then |
| returns an <a class="link" href="../../main_overview/error_handling.html#overflow_error">overflow_error</a>. |
| </p> |
| <a name="math_toolkit.utils.next_float.nextafter.examples___nextafter"></a><h5> |
| <a name="id1160855"></a> |
| <a class="link" href="nextafter.html#math_toolkit.utils.next_float.nextafter.examples___nextafter">Examples |
| - nextafter</a> |
| </h5> |
| <p> |
| The two representations using a 32-bit float either side of unity are: |
| |
| </p> |
| <pre class="programlisting"><span class="identifier">The</span> <span class="identifier">nearest</span> <span class="special">(</span><span class="identifier">exact</span><span class="special">)</span> <span class="identifier">representation</span> <span class="identifier">of</span> <span class="number">1.F</span> <span class="identifier">is</span> <span class="number">1.00000000</span> |
| <span class="identifier">nextafter</span><span class="special">(</span><span class="number">1.F</span><span class="special">,</span> <span class="number">999</span><span class="special">)</span> <span class="identifier">is</span> <span class="number">1.00000012</span> |
| <span class="identifier">nextafter</span><span class="special">(</span><span class="number">1</span><span class="special">/</span><span class="identifier">f</span><span class="special">,</span> <span class="special">-</span><span class="number">999</span><span class="special">)</span> <span class="identifier">is</span> <span class="number">0.99999994</span> |
| |
| <span class="identifier">The</span> <span class="identifier">nearest</span> <span class="special">(</span><span class="keyword">not</span> <span class="identifier">exact</span><span class="special">)</span> <span class="identifier">representation</span> <span class="identifier">of</span> <span class="number">0.1F</span> <span class="identifier">is</span> <span class="number">0.100000001</span> |
| <span class="identifier">nextafter</span><span class="special">(</span><span class="number">0.1F</span><span class="special">,</span> <span class="number">10</span><span class="special">)</span> <span class="identifier">is</span> <span class="number">0.100000009</span> |
| <span class="identifier">nextafter</span><span class="special">(</span><span class="number">0.1F</span><span class="special">,</span> <span class="number">10</span><span class="special">)</span> <span class="identifier">is</span> <span class="number">0.099999994</span> |
| </pre> |
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| 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>) |
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