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			104 lines
		
	
	
		
			4.4 KiB
		
	
	
	
		
			HTML
		
	
	
	
	
	
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<!-- This manual is for FFTW
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(version 3.3.10, 10 December 2020).
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Copyright (C) 2003 Matteo Frigo.
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Copyright (C) 2003 Massachusetts Institute of Technology.
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Permission is granted to make and distribute verbatim copies of this
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Permission is granted to copy and distribute modified versions of this
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<title>MPI Initialization (FFTW 3.3.10)</title>
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<link href="Concept-Index.html" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="FFTW-MPI-Reference.html" rel="up" title="FFTW MPI Reference">
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<span id="MPI-Initialization"></span><div class="header">
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<p>
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Next: <a href="Using-MPI-Plans.html" accesskey="n" rel="next">Using MPI Plans</a>, Previous: <a href="MPI-Files-and-Data-Types.html" accesskey="p" rel="prev">MPI Files and Data Types</a>, Up: <a href="FFTW-MPI-Reference.html" accesskey="u" rel="up">FFTW MPI Reference</a>   [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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<hr>
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<span id="MPI-Initialization-1"></span><h4 class="subsection">6.12.2 MPI Initialization</h4>
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<p>Before calling any other FFTW MPI (‘<samp>fftw_mpi_</samp>’) function, and
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before importing any wisdom for MPI problems, you must call:
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</p>
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<span id="index-fftw_005fmpi_005finit-4"></span>
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<div class="example">
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<pre class="example">void fftw_mpi_init(void);
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</pre></div>
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<span id="index-fftw_005finit_005fthreads-3"></span>
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<p>If FFTW threads support is used, however, <code>fftw_mpi_init</code> should
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be called <em>after</em> <code>fftw_init_threads</code> (see <a href="Combining-MPI-and-Threads.html">Combining MPI and Threads</a>).  Calling <code>fftw_mpi_init</code> additional times (before
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<code>fftw_mpi_cleanup</code>) has no effect.
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</p>
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<p>If you want to deallocate all persistent data and reset FFTW to the
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pristine state it was in when you started your program, you can call:
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</p>
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<span id="index-fftw_005fmpi_005fcleanup-1"></span>
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<div class="example">
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<pre class="example">void fftw_mpi_cleanup(void);
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</pre></div>
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<span id="index-fftw_005fcleanup-1"></span>
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<p>(This calls <code>fftw_cleanup</code>, so you need not call the serial
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cleanup routine too, although it is safe to do so.)  After calling
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<code>fftw_mpi_cleanup</code>, all existing plans become undefined, and you
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should not attempt to execute or destroy them.  You must call
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<code>fftw_mpi_init</code> again after <code>fftw_mpi_cleanup</code> if you want
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to resume using the MPI FFTW routines.
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</p>
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