119 lines
5.9 KiB
HTML
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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<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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manual provided the copyright notice and this permission notice are
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preserved on all copies.
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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 notice identical to this one.
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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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approved by the Free Software Foundation. -->
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<head>
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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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</head>
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<body lang="en">
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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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</div>
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</body>
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</html>
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