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<h2><span class="refentrytitle">Struct template is_commutative</span></h2>
<p>boost::mpi::is_commutative &#8212; Determine if a function object type is commutative. </p>
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<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../mpi/reference.html#header.boost.mpi.operations_hpp" title="Header &lt;boost/mpi/operations.hpp&gt;">boost/mpi/operations.hpp</a>&gt;

</span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Op<span class="special">,</span> <span class="keyword">typename</span> T<span class="special">&gt;</span> 
<span class="keyword">struct</span> <a class="link" href="is_commutative.html" title="Struct template is_commutative">is_commutative</a> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">false_</span> <span class="special">{</span>
<span class="special">}</span><span class="special">;</span></pre></div>
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<a name="idp517317664"></a><h2>Description</h2>
<p>This trait determines if an operation <code class="computeroutput">Op</code> is commutative when applied to values of type <code class="computeroutput">T</code>. Parallel operations such as <code class="computeroutput">reduce</code> and <code class="computeroutput">prefix_sum</code> can be implemented more efficiently with commutative operations. To mark an operation as commutative, users should specialize <code class="computeroutput"><a class="link" href="is_commutative.html" title="Struct template is_commutative">is_commutative</a></code> and derive from the class <code class="computeroutput">mpl::true_</code>. </p>
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