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cannam@127: <title>FFTW 3.3.5: MPI Initialization</title>
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cannam@127: <a name="MPI-Initialization"></a>
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cannam@127: <p>
cannam@127: 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> [<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>
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cannam@127: <hr>
cannam@127: <a name="MPI-Initialization-1"></a>
cannam@127: <h4 class="subsection">6.12.2 MPI Initialization</h4>
cannam@127:
cannam@127: <p>Before calling any other FFTW MPI (‘<samp>fftw_mpi_</samp>’) function, and
cannam@127: before importing any wisdom for MPI problems, you must call:
cannam@127: </p>
cannam@127: <a name="index-fftw_005fmpi_005finit-4"></a>
cannam@127: <div class="example">
cannam@127: <pre class="example">void fftw_mpi_init(void);
cannam@127: </pre></div>
cannam@127:
cannam@127: <a name="index-fftw_005finit_005fthreads-3"></a>
cannam@127: <p>If FFTW threads support is used, however, <code>fftw_mpi_init</code> should
cannam@127: 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
cannam@127: <code>fftw_mpi_cleanup</code>) has no effect.
cannam@127: </p>
cannam@127:
cannam@127: <p>If you want to deallocate all persistent data and reset FFTW to the
cannam@127: pristine state it was in when you started your program, you can call:
cannam@127: </p>
cannam@127: <a name="index-fftw_005fmpi_005fcleanup-1"></a>
cannam@127: <div class="example">
cannam@127: <pre class="example">void fftw_mpi_cleanup(void);
cannam@127: </pre></div>
cannam@127:
cannam@127: <a name="index-fftw_005fcleanup-1"></a>
cannam@127: <p>(This calls <code>fftw_cleanup</code>, so you need not call the serial
cannam@127: cleanup routine too, although it is safe to do so.) After calling
cannam@127: <code>fftw_mpi_cleanup</code>, all existing plans become undefined, and you
cannam@127: should not attempt to execute or destroy them. You must call
cannam@127: <code>fftw_mpi_init</code> again after <code>fftw_mpi_cleanup</code> if you want
cannam@127: to resume using the MPI FFTW routines.
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