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| <div class="titlepage"><div><div><h3 class="title"> |
| <a name="math_toolkit.utils.fpclass"></a><a class="link" href="fpclass.html" title="Floating-Point Classification: Infinities and NaN's"> Floating-Point Classification: |
| Infinities and NaN's</a> |
| </h3></div></div></div> |
| <a name="math_toolkit.utils.fpclass.synopsis"></a><h5> |
| <a name="id1157706"></a> |
| <a class="link" href="fpclass.html#math_toolkit.utils.fpclass.synopsis">Synopsis</a> |
| </h5> |
| <pre class="programlisting"><span class="preprocessor">#define</span> <span class="identifier">FP_ZERO</span> <span class="comment">/* implementation specific value */</span> |
| <span class="preprocessor">#define</span> <span class="identifier">FP_NORMAL</span> <span class="comment">/* implementation specific value */</span> |
| <span class="preprocessor">#define</span> <span class="identifier">FP_INFINITE</span> <span class="comment">/* implementation specific value */</span> |
| <span class="preprocessor">#define</span> <span class="identifier">FP_NAN</span> <span class="comment">/* implementation specific value */</span> |
| <span class="preprocessor">#define</span> <span class="identifier">FP_SUBNORMAL</span> <span class="comment">/* implementation specific value */</span> |
| |
| <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> |
| <span class="keyword">int</span> <span class="identifier">fpclassify</span><span class="special">(</span><span class="identifier">T</span> <span class="identifier">t</span><span class="special">);</span> |
| |
| <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> |
| <span class="keyword">bool</span> <span class="identifier">isfinite</span><span class="special">(</span><span class="identifier">T</span> <span class="identifier">z</span><span class="special">);</span> <span class="comment">// Neither infinity nor NaN. |
| </span> |
| <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> |
| <span class="keyword">bool</span> <span class="identifier">isinf</span><span class="special">(</span><span class="identifier">T</span> <span class="identifier">t</span><span class="special">);</span> <span class="comment">// Infinity (+ or -). |
| </span> |
| <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> |
| <span class="keyword">bool</span> <span class="identifier">isnan</span><span class="special">(</span><span class="identifier">T</span> <span class="identifier">t</span><span class="special">);</span> <span class="comment">// NaN. |
| </span> |
| <span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> |
| <span class="keyword">bool</span> <span class="identifier">isnormal</span><span class="special">(</span><span class="identifier">T</span> <span class="identifier">t</span><span class="special">);</span> <span class="comment">// isfinite and not denormalised. |
| </span> |
| <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">fpclassify</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <p> |
| to use these functions. |
| </p> |
| <a name="math_toolkit.utils.fpclass.description"></a><h5> |
| <a name="id1158097"></a> |
| <a class="link" href="fpclass.html#math_toolkit.utils.fpclass.description">Description</a> |
| </h5> |
| <p> |
| These functions provide the same functionality as the macros with the same |
| name in C99, indeed if the C99 macros are available, then these functions |
| are implemented in terms of them, otherwise they rely on std::numeric_limits<> |
| to function. |
| </p> |
| <p> |
| Note that the definition of these functions <span class="emphasis"><em>does not suppress the |
| definition of these names as macros by math.h</em></span> on those platforms |
| that already provide these as macros. That mean that the following have differing |
| meanings: |
| </p> |
| <pre class="programlisting"><span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span><span class="special">;</span> |
| |
| <span class="comment">// This might call a global macro if defined, |
| </span><span class="comment">// but might not work if the type of z is unsupported |
| </span><span class="comment">// by the std lib macro: |
| </span><span class="identifier">isnan</span><span class="special">(</span><span class="identifier">z</span><span class="special">);</span> |
| <span class="comment">// |
| </span><span class="comment">// This calls the Boost version |
| </span><span class="comment">// (found via the "using namespace boost::math" declaration) |
| </span><span class="comment">// it works for any type that has numeric_limits support for type z: |
| </span><span class="special">(</span><span class="identifier">isnan</span><span class="special">)(</span><span class="identifier">z</span><span class="special">);</span> |
| <span class="comment">// |
| </span><span class="comment">// As above but with explicit namespace qualification. |
| </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">isnan</span><span class="special">)(</span><span class="identifier">z</span><span class="special">);</span> |
| <span class="comment">// |
| </span><span class="comment">// This will cause a compiler error if isnan is a native macro: |
| </span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span><span class="special">::</span><span class="identifier">isnan</span><span class="special">(</span><span class="identifier">z</span><span class="special">);</span> |
| <span class="comment">// So always use instead: |
| </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">isnan</span><span class="special">)(</span><span class="identifier">z</span><span class="special">);</span> |
| <span class="comment">// |
| </span><span class="comment">// You can also add a using statement, |
| </span><span class="comment">// globally to a .cpp file, or to a local function in a .hpp file. |
| </span><span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span><span class="special">::</span><span class="identifier">isnan</span><span class="special">;</span> |
| <span class="comment">// so you can write the shorter and less cluttered |
| </span><span class="special">(</span><span class="identifier">isnan</span><span class="special">)(</span><span class="identifier">z</span><span class="special">)</span> |
| <span class="comment">// But, as above, if isnan is a native macro, this causes a compiler error, |
| </span><span class="comment">// because the macro always 'gets' the name first, unless enclosed in () brackets. |
| </span></pre> |
| <p> |
| Detailed descriptions for each of these functions follows: |
| </p> |
| <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> |
| <span class="keyword">int</span> <span class="identifier">fpclassify</span><span class="special">(</span><span class="identifier">T</span> <span class="identifier">t</span><span class="special">);</span> |
| </pre> |
| <p> |
| Returns an integer value that classifies the value <span class="emphasis"><em>t</em></span>: |
| </p> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| fpclassify value |
| </p> |
| </th> |
| <th> |
| <p> |
| class of t. |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| FP_ZERO |
| </p> |
| </td> |
| <td> |
| <p> |
| If <span class="emphasis"><em>t</em></span> is zero. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| FP_NORMAL |
| </p> |
| </td> |
| <td> |
| <p> |
| If <span class="emphasis"><em>t</em></span> is a non-zero, non-denormalised finite |
| value. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| FP_INFINITE |
| </p> |
| </td> |
| <td> |
| <p> |
| If <span class="emphasis"><em>t</em></span> is plus or minus infinity. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| FP_NAN |
| </p> |
| </td> |
| <td> |
| <p> |
| If <span class="emphasis"><em>t</em></span> is a NaN. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| FP_SUBNORMAL |
| </p> |
| </td> |
| <td> |
| <p> |
| If <span class="emphasis"><em>t</em></span> is a denormalised number. |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> |
| <span class="keyword">bool</span> <span class="identifier">isfinite</span><span class="special">(</span><span class="identifier">T</span> <span class="identifier">z</span><span class="special">);</span> |
| </pre> |
| <p> |
| Returns true only if <span class="emphasis"><em>z</em></span> is not an infinity or a NaN. |
| </p> |
| <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> |
| <span class="keyword">bool</span> <span class="identifier">isinf</span><span class="special">(</span><span class="identifier">T</span> <span class="identifier">t</span><span class="special">);</span> |
| </pre> |
| <p> |
| Returns true only if <span class="emphasis"><em>z</em></span> is plus or minus infinity. |
| </p> |
| <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> |
| <span class="keyword">bool</span> <span class="identifier">isnan</span><span class="special">(</span><span class="identifier">T</span> <span class="identifier">t</span><span class="special">);</span> |
| </pre> |
| <p> |
| Returns true only if <span class="emphasis"><em>z</em></span> is a <a href="http://en.wikipedia.org/wiki/NaN" target="_top">NaN</a>. |
| </p> |
| <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> |
| <span class="keyword">bool</span> <span class="identifier">isnormal</span><span class="special">(</span><span class="identifier">T</span> <span class="identifier">t</span><span class="special">);</span> |
| </pre> |
| <p> |
| Returns true only if <span class="emphasis"><em>z</em></span> is a normal number (not zero, |
| infinite, NaN, or denormalised). |
| </p> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
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| <td align="right"><div class="copyright-footer">Copyright © 2006 , 2007, 2008, 2009, 2010 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>) |
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