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			119 lines
		
	
	
		
			5.9 KiB
		
	
	
	
		
			HTML
		
	
	
	
	
	
|   | <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> | ||
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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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|  | <title>Using MPI Plans (FFTW 3.3.10)</title> | ||
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|  | <span id="Using-MPI-Plans"></span><div class="header"> | ||
|  | <p> | ||
|  | 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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|  | <span id="Using-MPI-Plans-1"></span><h4 class="subsection">6.12.3 Using MPI Plans</h4> | ||
|  | 
 | ||
|  | <p>Once an MPI plan is created, you can execute and destroy it using | ||
|  | <code>fftw_execute</code>, <code>fftw_destroy_plan</code>, and the other functions | ||
|  | in the serial interface that operate on generic plans (see <a href="Using-Plans.html">Using Plans</a>).   | ||
|  | </p> | ||
|  | <span id="index-collective-function-3"></span> | ||
|  | <span id="index-MPI-communicator-1"></span> | ||
|  | <p>The <code>fftw_execute</code> and <code>fftw_destroy_plan</code> functions, applied to | ||
|  | MPI plans, are <em>collective</em> calls: they must be called for all processes | ||
|  | in the communicator that was used to create the plan. | ||
|  | </p> | ||
|  | <span id="index-new_002darray-execution-1"></span> | ||
|  | <p>You must <em>not</em> use the serial new-array plan-execution functions | ||
|  | <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 | ||
|  | problem type, and there are specific new-array execute functions for MPI plans: | ||
|  | </p> | ||
|  | <span id="index-fftw_005fmpi_005fexecute_005fdft"></span> | ||
|  | <span id="index-fftw_005fmpi_005fexecute_005fdft_005fr2c"></span> | ||
|  | <span id="index-fftw_005fmpi_005fexecute_005fdft_005fc2r"></span> | ||
|  | <span id="index-fftw_005fmpi_005fexecute_005fr2r"></span> | ||
|  | <div class="example"> | ||
|  | <pre class="example">void fftw_mpi_execute_dft(fftw_plan p, fftw_complex *in, fftw_complex *out); | ||
|  | void fftw_mpi_execute_dft_r2c(fftw_plan p, double *in, fftw_complex *out); | ||
|  | void fftw_mpi_execute_dft_c2r(fftw_plan p, fftw_complex *in, double *out); | ||
|  | void fftw_mpi_execute_r2r(fftw_plan p, double *in, double *out); | ||
|  | </pre></div> | ||
|  | 
 | ||
|  | <span id="index-alignment-3"></span> | ||
|  | <span id="index-fftw_005fmalloc-6"></span> | ||
|  | <p>These functions have the same restrictions as those of the serial | ||
|  | new-array execute functions.  They are <em>always</em> safe to apply to | ||
|  | the <em>same</em> <code>in</code> and <code>out</code> arrays that were used to | ||
|  | create the plan.  They can only be applied to new arrarys if those | ||
|  | arrays have the same types, dimensions, in-placeness, and alignment as | ||
|  | the original arrays, where the best way to ensure the same alignment | ||
|  | is to use FFTW’s <code>fftw_malloc</code> and related allocation functions | ||
|  | for all arrays (see <a href="Memory-Allocation.html">Memory Allocation</a>).  Note that distributed | ||
|  | transposes (see <a href="FFTW-MPI-Transposes.html">FFTW MPI Transposes</a>) use | ||
|  | <code>fftw_mpi_execute_r2r</code>, since they count as rank-zero r2r plans | ||
|  | from FFTW’s perspective. | ||
|  | </p> | ||
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|  | <div class="header"> | ||
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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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