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Current fftw source
author Chris Cannam
date Tue, 18 Oct 2016 13:40:26 +0100
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Chris@42 25 <title>FFTW 3.3.5: MPI Initialization</title>
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Chris@42 72 <a name="MPI-Initialization"></a>
Chris@42 73 <div class="header">
Chris@42 74 <p>
Chris@42 75 Next: <a href="Using-MPI-Plans.html#Using-MPI-Plans" accesskey="n" rel="next">Using MPI Plans</a>, Previous: <a href="MPI-Files-and-Data-Types.html#MPI-Files-and-Data-Types" accesskey="p" rel="prev">MPI Files and Data Types</a>, Up: <a href="FFTW-MPI-Reference.html#FFTW-MPI-Reference" accesskey="u" rel="up">FFTW MPI Reference</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
Chris@42 76 </div>
Chris@42 77 <hr>
Chris@42 78 <a name="MPI-Initialization-1"></a>
Chris@42 79 <h4 class="subsection">6.12.2 MPI Initialization</h4>
Chris@42 80
Chris@42 81 <p>Before calling any other FFTW MPI (&lsquo;<samp>fftw_mpi_</samp>&rsquo;) function, and
Chris@42 82 before importing any wisdom for MPI problems, you must call:
Chris@42 83 </p>
Chris@42 84 <a name="index-fftw_005fmpi_005finit-4"></a>
Chris@42 85 <div class="example">
Chris@42 86 <pre class="example">void fftw_mpi_init(void);
Chris@42 87 </pre></div>
Chris@42 88
Chris@42 89 <a name="index-fftw_005finit_005fthreads-3"></a>
Chris@42 90 <p>If FFTW threads support is used, however, <code>fftw_mpi_init</code> should
Chris@42 91 be called <em>after</em> <code>fftw_init_threads</code> (see <a href="Combining-MPI-and-Threads.html#Combining-MPI-and-Threads">Combining MPI and Threads</a>). Calling <code>fftw_mpi_init</code> additional times (before
Chris@42 92 <code>fftw_mpi_cleanup</code>) has no effect.
Chris@42 93 </p>
Chris@42 94
Chris@42 95 <p>If you want to deallocate all persistent data and reset FFTW to the
Chris@42 96 pristine state it was in when you started your program, you can call:
Chris@42 97 </p>
Chris@42 98 <a name="index-fftw_005fmpi_005fcleanup-1"></a>
Chris@42 99 <div class="example">
Chris@42 100 <pre class="example">void fftw_mpi_cleanup(void);
Chris@42 101 </pre></div>
Chris@42 102
Chris@42 103 <a name="index-fftw_005fcleanup-1"></a>
Chris@42 104 <p>(This calls <code>fftw_cleanup</code>, so you need not call the serial
Chris@42 105 cleanup routine too, although it is safe to do so.) After calling
Chris@42 106 <code>fftw_mpi_cleanup</code>, all existing plans become undefined, and you
Chris@42 107 should not attempt to execute or destroy them. You must call
Chris@42 108 <code>fftw_mpi_init</code> again after <code>fftw_mpi_cleanup</code> if you want
Chris@42 109 to resume using the MPI FFTW routines.
Chris@42 110 </p>
Chris@42 111
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Chris@42 115 </html>