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| cannam@127 | 25 <title>FFTW 3.3.5: MPI Initialization</title> | 
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| cannam@127 | 72 <a name="MPI-Initialization"></a> | 
| cannam@127 | 73 <div class="header"> | 
| cannam@127 | 74 <p> | 
| cannam@127 | 75 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> | 
| cannam@127 | 76 </div> | 
| cannam@127 | 77 <hr> | 
| cannam@127 | 78 <a name="MPI-Initialization-1"></a> | 
| cannam@127 | 79 <h4 class="subsection">6.12.2 MPI Initialization</h4> | 
| cannam@127 | 80 | 
| cannam@127 | 81 <p>Before calling any other FFTW MPI (‘<samp>fftw_mpi_</samp>’) function, and | 
| cannam@127 | 82 before importing any wisdom for MPI problems, you must call: | 
| cannam@127 | 83 </p> | 
| cannam@127 | 84 <a name="index-fftw_005fmpi_005finit-4"></a> | 
| cannam@127 | 85 <div class="example"> | 
| cannam@127 | 86 <pre class="example">void fftw_mpi_init(void); | 
| cannam@127 | 87 </pre></div> | 
| cannam@127 | 88 | 
| cannam@127 | 89 <a name="index-fftw_005finit_005fthreads-3"></a> | 
| cannam@127 | 90 <p>If FFTW threads support is used, however, <code>fftw_mpi_init</code> should | 
| cannam@127 | 91 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 | 92 <code>fftw_mpi_cleanup</code>) has no effect. | 
| cannam@127 | 93 </p> | 
| cannam@127 | 94 | 
| cannam@127 | 95 <p>If you want to deallocate all persistent data and reset FFTW to the | 
| cannam@127 | 96 pristine state it was in when you started your program, you can call: | 
| cannam@127 | 97 </p> | 
| cannam@127 | 98 <a name="index-fftw_005fmpi_005fcleanup-1"></a> | 
| cannam@127 | 99 <div class="example"> | 
| cannam@127 | 100 <pre class="example">void fftw_mpi_cleanup(void); | 
| cannam@127 | 101 </pre></div> | 
| cannam@127 | 102 | 
| cannam@127 | 103 <a name="index-fftw_005fcleanup-1"></a> | 
| cannam@127 | 104 <p>(This calls <code>fftw_cleanup</code>, so you need not call the serial | 
| cannam@127 | 105 cleanup routine too, although it is safe to do so.)  After calling | 
| cannam@127 | 106 <code>fftw_mpi_cleanup</code>, all existing plans become undefined, and you | 
| cannam@127 | 107 should not attempt to execute or destroy them.  You must call | 
| cannam@127 | 108 <code>fftw_mpi_init</code> again after <code>fftw_mpi_cleanup</code> if you want | 
| cannam@127 | 109 to resume using the MPI FFTW routines. | 
| cannam@127 | 110 </p> | 
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