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<div class="title">NumTraits< T > Class Template Reference<div class="ingroups"><a class="el" href="group__Core__Module.html">Core module</a></div></div> </div>
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<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><h3>template<typename T><br/>
class Eigen::NumTraits< T ></h3>
<p>Holds information about the various numeric (i.e. scalar) types allowed by <a class="el" href="namespaceEigen.html" title="Namespace containing all symbols from the Eigen library. ">Eigen</a>. </p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">T</td><td>the numeric type at hand</td></tr>
</table>
</dd>
</dl>
<p>This class stores enums, typedefs and static methods giving information about a numeric type.</p>
<p>The provided data consists of: </p>
<ul>
<li>A typedef <em>Real</em>, giving the "real part" type of <em>T</em>. If <em>T</em> is already real, then <em>Real</em> is just a typedef to <em>T</em>. If <em>T</em> is <code>std::complex<U></code> then <em>Real</em> is a typedef to <em>U</em>. </li>
<li>A typedef <em>NonInteger</em>, giving the type that should be used for operations producing non-integral values, such as quotients, square roots, etc. If <em>T</em> is a floating-point type, then this typedef just gives <em>T</em> again. Note however that many <a class="el" href="namespaceEigen.html" title="Namespace containing all symbols from the Eigen library. ">Eigen</a> functions such as internal::sqrt simply refuse to take integers. Outside of a few cases, <a class="el" href="namespaceEigen.html" title="Namespace containing all symbols from the Eigen library. ">Eigen</a> doesn't do automatic type promotion. Thus, this typedef is only intended as a helper for code that needs to explicitly promote types. </li>
<li>A typedef <em>Nested</em> giving the type to use to nest a value inside of the expression tree. If you don't know what this means, just use <em>T</em> here. </li>
<li>An enum value <em>IsComplex</em>. It is equal to 1 if <em>T</em> is a <code>std::complex</code> type, and to 0 otherwise. </li>
<li>An enum value <em>IsInteger</em>. It is equal to <code>1</code> if <em>T</em> is an integer type such as <code>int</code>, and to <code>0</code> otherwise. </li>
<li>Enum values ReadCost, AddCost and MulCost representing a rough estimate of the number of CPU cycles needed to by move / add / mul instructions respectively, assuming the data is already stored in CPU registers. Stay vague here. No need to do architecture-specific stuff. </li>
<li>An enum value <em>IsSigned</em>. It is equal to <code>1</code> if <em>T</em> is a signed type and to 0 if <em>T</em> is unsigned. </li>
<li>An enum value <em>RequireInitialization</em>. It is equal to <code>1</code> if the constructor of the numeric type <em>T</em> must be called, and to 0 if it is safe not to call it. Default is 0 if <em>T</em> is an arithmetic type, and 1 otherwise. </li>
<li>An epsilon() function which, unlike std::numeric_limits::epsilon(), returns a <em>Real</em> instead of a <em>T</em>. </li>
<li>A dummy_precision() function returning a weak epsilon value. It is mainly used as a default value by the fuzzy comparison operators. </li>
<li>highest() and lowest() functions returning the highest and lowest possible values respectively. </li>
</ul>
</div>
<p>Inherits GenericNumTraits< T >.</p>
<hr/>The documentation for this class was generated from the following file:<ul>
<li><a class="el" href="NumTraits_8h_source.html">NumTraits.h</a></li>
</ul>
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