1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>Function max_element</title> 5<link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../index.html" title="Chapter 1. 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22<div class="spirit-nav"> 23<a accesskey="p" href="lower_bound.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../boost_compute/reference.html#header.boost.compute.algorithm.max_element_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="merge.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="refentry"> 26<a name="boost.compute.max_element"></a><div class="titlepage"></div> 27<div class="refnamediv"> 28<h2><span class="refentrytitle">Function max_element</span></h2> 29<p>boost::compute::max_element</p> 30</div> 31<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> 32<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="../../boost_compute/reference.html#header.boost.compute.algorithm.max_element_hpp" title="Header <boost/compute/algorithm/max_element.hpp>">boost/compute/algorithm/max_element.hpp</a>> 33 34</span> 35<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> InputIterator<span class="special">,</span> <span class="keyword">typename</span> Compare<span class="special">></span> 36 <span class="identifier">InputIterator</span> 37 <span class="identifier">max_element</span><span class="special">(</span><span class="identifier">InputIterator</span> first<span class="special">,</span> <span class="identifier">InputIterator</span> last<span class="special">,</span> <span class="identifier">Compare</span> compare<span class="special">,</span> 38 <span class="identifier">command_queue</span> <span class="special">&</span> queue <span class="special">=</span> <span class="identifier">system</span><span class="special">::</span><span class="identifier">default_queue</span><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span> 39<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> InputIterator<span class="special">></span> 40 <span class="identifier">InputIterator</span> 41 <span class="identifier">max_element</span><span class="special">(</span><span class="identifier">InputIterator</span> first<span class="special">,</span> <span class="identifier">InputIterator</span> last<span class="special">,</span> 42 <span class="identifier">command_queue</span> <span class="special">&</span> queue <span class="special">=</span> <span class="identifier">system</span><span class="special">::</span><span class="identifier">default_queue</span><span class="special">(</span><span class="special">)</span><span class="special">)</span><span class="special">;</span></pre></div> 43<div class="refsect1"> 44<a name="idm45849521038112"></a><h2>Description</h2> 45<p>Returns an iterator pointing to the element in the range [<code class="computeroutput">first</code>, <code class="computeroutput">last</code>) with the maximum value.</p> 46<p> 47For example, to find <code class="computeroutput">int2</code> value with maximum first component in given vector: </p> 48<pre class="programlisting"><span class="comment">// comparison function object</span> 49<span class="identifier">BOOST_COMPUTE_FUNCTION</span><span class="special">(</span><span class="keyword">bool</span><span class="special">,</span> <span class="identifier">compare_first</span><span class="special">,</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">int2_</span> <span class="special">&</span><span class="identifier">a</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">int2_</span> <span class="special">&</span><span class="identifier">b</span><span class="special">)</span><span class="special">,</span> 50<span class="special">{</span> 51 <span class="keyword">return</span> <span class="identifier">a</span><span class="special">.</span><span class="identifier">x</span> <span class="special"><</span> <span class="identifier">b</span><span class="special">.</span><span class="identifier">x</span><span class="special">;</span> 52<span class="special">}</span><span class="special">)</span><span class="special">;</span> 53 54<span class="comment">// create vector</span> 55<span class="identifier">boost</span><span class="special">::</span><span class="identifier">compute</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">uint2_</span><span class="special">></span> <span class="identifier">data</span> <span class="special">=</span> <span class="special">...</span> 56 57<span class="identifier">boost</span><span class="special">::</span><span class="identifier">compute</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">uint2_</span><span class="special">></span><span class="special">::</span><span class="identifier">iterator</span> <span class="identifier">max</span> <span class="special">=</span> 58 <span class="identifier">boost</span><span class="special">::</span><span class="identifier">compute</span><span class="special">::</span><span class="identifier">max_element</span><span class="special">(</span><span class="identifier">data</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(</span><span class="special">)</span><span class="special">,</span> <span class="identifier">data</span><span class="special">.</span><span class="identifier">end</span><span class="special">(</span><span class="special">)</span><span class="special">,</span> <span class="identifier">compare_first</span><span class="special">,</span> <span class="identifier">queue</span><span class="special">)</span><span class="special">;</span> 59</pre> 60<p>Space complexity on CPUs: \Omega(1)<br> 61 Space complexity on GPUs: \Omega(N)</p> 62<p><span class="bold"><strong>See Also:</strong></span></p> 63<p>min_element() </p> 64<p> 65</p> 66<p> 67</p> 68<div class="variablelist"><table border="0" class="variablelist compact"> 69<colgroup> 70<col align="left" valign="top"> 71<col> 72</colgroup> 73<tbody><tr> 74<td><p><span class="term">Parameters:</span></p></td> 75<td><div class="variablelist"><table border="0" class="variablelist compact"> 76<colgroup> 77<col align="left" valign="top"> 78<col> 79</colgroup> 80<tbody> 81<tr> 82<td><p><span class="term"><code class="computeroutput">compare</code></span></p></td> 83<td><p>comparison function object which returns true if the first argument is less than (i.e. is ordered before) the second. </p></td> 84</tr> 85<tr> 86<td><p><span class="term"><code class="computeroutput">first</code></span></p></td> 87<td><p>first element in the input range </p></td> 88</tr> 89<tr> 90<td><p><span class="term"><code class="computeroutput">last</code></span></p></td> 91<td><p>last element in the input range </p></td> 92</tr> 93<tr> 94<td><p><span class="term"><code class="computeroutput">queue</code></span></p></td> 95<td><p>command queue to perform the operation</p></td> 96</tr> 97</tbody> 98</table></div></td> 99</tr></tbody> 100</table></div> 101</div> 102</div> 103<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 104<td align="left"></td> 105<td align="right"><div class="copyright-footer">Copyright © 2013, 2014 Kyle Lutz<p> 106 Distributed under the Boost Software License, Version 1.0. (See accompanying 107 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>) 108 </p> 109</div></td> 110</tr></table> 111<hr> 112<div class="spirit-nav"> 113<a accesskey="p" href="lower_bound.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../boost_compute/reference.html#header.boost.compute.algorithm.max_element_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="merge.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> 114</div> 115</body> 116</html> 117
