1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 2<html> 3<head> 4<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 5<title>Struct template is_commutative</title> 6<link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> 7<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 8<link rel="home" href="../../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> 9<link rel="up" href="../../mpi/reference.html#header.boost.mpi.operations_hpp" title="Header <boost/mpi/operations.hpp>"> 10<link rel="prev" href="bitwise_xor.html" title="Struct template bitwise_xor"> 11<link rel="next" href="is_mpi_op.html" title="Struct template is_mpi_op"> 12</head> 13<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 14<table cellpadding="2" width="100%"><tr> 15<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td> 16<td align="center"><a href="../../../../index.html">Home</a></td> 17<td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td> 18<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 19<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 20<td align="center"><a href="../../../../more/index.htm">More</a></td> 21</tr></table> 22<hr> 23<div class="spirit-nav"> 24<a accesskey="p" href="bitwise_xor.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../mpi/reference.html#header.boost.mpi.operations_hpp"><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="is_mpi_op.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 25</div> 26<div class="refentry"> 27<a name="boost.mpi.is_commutative"></a><div class="titlepage"></div> 28<div class="refnamediv"> 29<h2><span class="refentrytitle">Struct template is_commutative</span></h2> 30<p>boost::mpi::is_commutative — Determine if a function object type is commutative. </p> 31</div> 32<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> 33<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../mpi/reference.html#header.boost.mpi.operations_hpp" title="Header <boost/mpi/operations.hpp>">boost/mpi/operations.hpp</a>> 34 35</span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Op<span class="special">,</span> <span class="keyword">typename</span> T<span class="special">></span> 36<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> 37<span class="special">}</span><span class="special">;</span></pre></div> 38<div class="refsect1"> 39<a name="id-1.3.27.7.18.7.4"></a><h2>Description</h2> 40<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> 41</div> 42</div> 43<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 44<td align="left"></td> 45<td align="right"><div class="copyright-footer">Copyright © 2005-2007 Douglas Gregor, 46 Matthias Troyer, Trustees of Indiana University<p> 47 Distributed under the Boost Software License, Version 1.0. (See accompanying 48 file LICENSE_1_0.txt or copy at <ulink url="http://www.boost.org/LICENSE_1_0.txt"> 49 http://www.boost.org/LICENSE_1_0.txt </ulink>) 50 </p> 51</div></td> 52</tr></table> 53<hr> 54<div class="spirit-nav"> 55<a accesskey="p" href="bitwise_xor.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../mpi/reference.html#header.boost.mpi.operations_hpp"><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="is_mpi_op.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> 56</div> 57</body> 58</html> 59
