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  25 <div class="refentry">
  26 <a name="boost.mpi.scatter"></a><div class="titlepage"></div>
  27 <div class="refnamediv">
  28 <h2><span class="refentrytitle">Function scatter</span></h2>
  29 <p>boost::mpi::scatter &#8212; Scatter the values stored at the root to all processes within the communicator. </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: &lt;<a class="link" href="../../mpi/reference.html#header.boost.mpi.collectives_hpp" title="Header &lt;boost/mpi/collectives.hpp&gt;">boost/mpi/collectives.hpp</a>&gt;
  33
  34 </span>
  35 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span>
  36   <span class="keyword">void</span> <span class="identifier">scatter</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span> <span class="identifier">T</span> <span class="special">&gt;</span> <span class="special">&amp;</span> in_values<span class="special">,</span>
  37                <span class="identifier">T</span> <span class="special">&amp;</span> out_value<span class="special">,</span> <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span>
  38 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span>
  39   <span class="keyword">void</span> <span class="identifier">scatter</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">T</span> <span class="special">*</span> in_values<span class="special">,</span> <span class="identifier">T</span> <span class="special">&amp;</span> out_value<span class="special">,</span>
  40                <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span>
  41 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span>
  42   <span class="keyword">void</span> <span class="identifier">scatter</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="identifier">T</span> <span class="special">&amp;</span> out_value<span class="special">,</span> <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span>
  43 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span>
  44   <span class="keyword">void</span> <span class="identifier">scatter</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span> <span class="identifier">T</span> <span class="special">&gt;</span> <span class="special">&amp;</span> in_values<span class="special">,</span>
  45                <span class="identifier">T</span> <span class="special">*</span> out_values<span class="special">,</span> <span class="keyword">int</span> n<span class="special">,</span> <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span>
  46 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span>
  47   <span class="keyword">void</span> <span class="identifier">scatter</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="keyword">const</span> <span class="identifier">T</span> <span class="special">*</span> in_values<span class="special">,</span> <span class="identifier">T</span> <span class="special">*</span> out_values<span class="special">,</span>
  48                <span class="keyword">int</span> n<span class="special">,</span> <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span>
  49 <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">&gt;</span>
  50   <span class="keyword">void</span> <span class="identifier">scatter</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="communicator.html" title="Class communicator">communicator</a> <span class="special">&amp;</span> comm<span class="special">,</span> <span class="identifier">T</span> <span class="special">*</span> out_values<span class="special">,</span> <span class="keyword">int</span> n<span class="special">,</span> <span class="keyword">int</span> root<span class="special">)</span><span class="special">;</span></pre></div>
  51 <div class="refsect1">
  52 <a name="id2507154"></a><h2>Description</h2>
  53 <p><code class="computeroutput">scatter</code> is a collective algorithm that scatters the values stored in the <code class="computeroutput">root</code> process (inside a vector) to all of the processes in the communicator. The vector <code class="computeroutput">out_values</code> (only significant at the <code class="computeroutput">root</code>) is indexed by the process number to which the corresponding value will be sent. The type <code class="computeroutput">T</code> of the values may be any type that is serializable or has an associated MPI data type.</p>
  54 <p>When the type <code class="computeroutput">T</code> has an associated MPI data type, this routine invokes <code class="computeroutput">MPI_Scatter</code> to scatter the values.</p>
  55 <p>
  56 </p>
  57 <div class="variablelist"><table border="0">
  58 <col align="left" valign="top">
  59 <tbody><tr>
  60 <td><p><span class="term">Parameters:</span></p></td>
  61 <td><div class="variablelist"><table border="0">
  62 <col align="left" valign="top">
  63 <tbody>
  64 <tr>
  65 <td><p><span class="term"><code class="computeroutput">comm</code></span></p></td>
  66 <td><p>The communicator over which the gather will occur.</p></td>
  67 </tr>
  68 <tr>
  69 <td><p><span class="term"><code class="computeroutput">in_values</code></span></p></td>
  70 <td><p>A vector or pointer to storage that will contain the values to send to each process, indexed by the process rank. For non-root processes, this parameter may be omitted. If it is still provided, however, it will be unchanged.</p></td>
  71 </tr>
  72 <tr>
  73 <td><p><span class="term"><code class="computeroutput">out_value</code></span></p></td>
  74 <td><p>The value received by each process. When scattering an array of values, <code class="computeroutput">out_values</code> points to the <code class="computeroutput">n</code> values that will be received by each process.</p></td>
  75 </tr>
  76 <tr>
  77 <td><p><span class="term"><code class="computeroutput">root</code></span></p></td>
  78 <td><p>The process ID number that will scatter the values. This value must be the same on all processes. </p></td>
  79 </tr>
  80 </tbody>
  81 </table></div></td>
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  87 <td align="left"></td>
  88 <td align="right"><div class="copyright-footer">Copyright &#169; 2005-2007 Douglas Gregor,
  89       Matthias Troyer, Trustees of Indiana University<p>
  90         Distributed under the Boost Software License, Version 1.0. (See accompanying
  91         file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">
  92         http://www.boost.org/LICENSE_1_0.txt </a>)
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