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			119 lines
		
	
	
		
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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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								manual provided the copyright notice and this permission notice are
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								Permission is granted to copy and distribute modified versions of this
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								manual under the conditions for verbatim copying, provided that the
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								entire resulting derived work is distributed under the terms of a
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								Permission is granted to copy and distribute translations of this manual
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								into another language, under the above conditions for modified versions,
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								except that this permission notice may be stated in a translation
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								<title>Using MPI Plans (FFTW 3.3.10)</title>
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								<meta name="description" content="Using MPI Plans (FFTW 3.3.10)">
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								<link href="index.html" rel="start" title="Top">
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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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								<link href="MPI-Data-Distribution-Functions.html" rel="next" title="MPI Data Distribution Functions">
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								<span id="Using-MPI-Plans"></span><div class="header">
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								<p>
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								Next: <a href="MPI-Data-Distribution-Functions.html" accesskey="n" rel="next">MPI Data Distribution Functions</a>, Previous: <a href="MPI-Initialization.html" accesskey="p" rel="prev">MPI Initialization</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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								</div>
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								<hr>
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								<span id="Using-MPI-Plans-1"></span><h4 class="subsection">6.12.3 Using MPI Plans</h4>
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								<p>Once an MPI plan is created, you can execute and destroy it using
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								<code>fftw_execute</code>, <code>fftw_destroy_plan</code>, and the other functions
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								in the serial interface that operate on generic plans (see <a href="Using-Plans.html">Using Plans</a>).  
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								</p>
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								<span id="index-collective-function-3"></span>
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								<span id="index-MPI-communicator-1"></span>
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								<p>The <code>fftw_execute</code> and <code>fftw_destroy_plan</code> functions, applied to
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								MPI plans, are <em>collective</em> calls: they must be called for all processes
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								in the communicator that was used to create the plan.
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								</p>
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								<span id="index-new_002darray-execution-1"></span>
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								<p>You must <em>not</em> use the serial new-array plan-execution functions
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								<code>fftw_execute_dft</code> and so on (see <a href="New_002darray-Execute-Functions.html">New-array Execute Functions</a>) with MPI plans.  Such functions are specialized to the
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								problem type, and there are specific new-array execute functions for MPI plans:
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								</p>
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								<span id="index-fftw_005fmpi_005fexecute_005fdft"></span>
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								<span id="index-fftw_005fmpi_005fexecute_005fdft_005fr2c"></span>
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								<span id="index-fftw_005fmpi_005fexecute_005fdft_005fc2r"></span>
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								<span id="index-fftw_005fmpi_005fexecute_005fr2r"></span>
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								<div class="example">
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								<pre class="example">void fftw_mpi_execute_dft(fftw_plan p, fftw_complex *in, fftw_complex *out);
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								void fftw_mpi_execute_dft_r2c(fftw_plan p, double *in, fftw_complex *out);
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								void fftw_mpi_execute_dft_c2r(fftw_plan p, fftw_complex *in, double *out);
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								void fftw_mpi_execute_r2r(fftw_plan p, double *in, double *out);
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								</pre></div>
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								<span id="index-alignment-3"></span>
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								<span id="index-fftw_005fmalloc-6"></span>
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								<p>These functions have the same restrictions as those of the serial
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								new-array execute functions.  They are <em>always</em> safe to apply to
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								the <em>same</em> <code>in</code> and <code>out</code> arrays that were used to
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								create the plan.  They can only be applied to new arrarys if those
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								arrays have the same types, dimensions, in-placeness, and alignment as
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								the original arrays, where the best way to ensure the same alignment
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								is to use FFTW’s <code>fftw_malloc</code> and related allocation functions
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								for all arrays (see <a href="Memory-Allocation.html">Memory Allocation</a>).  Note that distributed
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								transposes (see <a href="FFTW-MPI-Transposes.html">FFTW MPI Transposes</a>) use
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								<code>fftw_mpi_execute_r2r</code>, since they count as rank-zero r2r plans
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								from FFTW’s perspective.
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								</p>
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								<hr>
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								<div class="header">
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								<p>
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								Next: <a href="MPI-Data-Distribution-Functions.html" accesskey="n" rel="next">MPI Data Distribution Functions</a>, Previous: <a href="MPI-Initialization.html" accesskey="p" rel="prev">MPI Initialization</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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