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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"><head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> <style type="text/css"> body { font-family: Verdana, Arial, Helvetica, sans-serif;} a.at-term { font-style: italic; } </style> <title>Parallel for/DO</title> <meta name="Generator" content="ATutor"> <meta name="Keywords" content=""></head><body> <p>The parallel for/DO construct splits the iterations of the immediately following loop among the threads in the team. </p>
<p>Example: </p>
<pre><code>#pragma omp parallel shared(a,b) private(j)
{
#pragma omp for
for (j = 0; j < N; j++)
a[j] = a[j] + b[j];
}</code></pre>
<p>By default, there is a barrier at the end of the loop: the threads wait until all are finished and then proceed. You can use the <em>nowait</em> clause to allow
threads to continue without waiting. This is recommended if it is known that subsequent work does not depend on all loop iterations having been completed. </p>
<p>Detailed syntax for the parallel for/DO is as follows: </p>
<p class="codelang">C/C++</p>
<pre><code>#pragma omp for [clause [clause]...]
for loop</code></pre>
<p>where <em>clause</em> is one of </p>
<ul>
<li><code>private(<em>list</em>)</code> </li>
<li><code>firstprivate(<em>list</em>)</code> </li>
<li><code>lastprivate(<em>list</em>)</code> </li>
<li><code>reduction(<em>operator:list</em>)</code> </li>
<li><code>ordered</code> </li>
<li><code>schedule(<em>kind [, chunk_size]</em>)</code> </li>
<li><code>nowait</code> </li>
</ul>
<p class="codelang">Detailed Syntax (Fortran):</p>
<pre><code>c$omp do [clause [clause]...]
do loop
[c$omp end do [nowait]]</code></pre>
<p>where <b>clause</b> is one of </p>
<ul>
<li><code>private(<em>list</em>)</code> </li>
<li><code>firstprivate(<em>list</em>)</code> </li>
<li><code>lastprivate(<em>list</em>)</code> </li>
<li><code>reduction(<em>operator:list</em>)</code> </li>
<li><code>ordered</code> </li>
<li><code>schedule(<em>kind [, chunk_size]</em>)</code> </li>
</ul>
<p>For Fortran 90, use !$OMP and F90-style line continuation. </p></body></html>⌨️ 快捷键说明
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