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<h3 class="section">6.2 Linking and Initializing MPI FFTW</h3>
<p>Programs using the MPI FFTW routines should be linked with
<code>-lfftw3_mpi -lfftw3 -lm</code> on Unix in double precision,
<code>-lfftw3f_mpi -lfftw3f -lm</code> in single precision, and so on
(see <a href="Precision.html#Precision">Precision</a>). You will also need to link with whatever library
is responsible for MPI on your system; in most MPI implementations,
there is a special compiler alias named <code>mpicc</code> to compile and
link MPI code.
<a name="index-mpicc-351"></a><a name="index-linking-on-Unix-352"></a><a name="index-precision-353"></a>
<p><a name="index-fftw_005finit_005fthreads-354"></a>Before calling any FFTW routines except possibly
<code>fftw_init_threads</code> (see <a href="Combining-MPI-and-Threads.html#Combining-MPI-and-Threads">Combining MPI and Threads</a>), but after calling
<code>MPI_Init</code>, you should call the function:
<pre class="example"> void fftw_mpi_init(void);
</pre>
<p><a name="index-fftw_005fmpi_005finit-355"></a>
If, at the end of your program, you want to get rid of all memory and
other resources allocated internally by FFTW, for both the serial and
MPI routines, you can call:
<pre class="example"> void fftw_mpi_cleanup(void);
</pre>
<p><a name="index-fftw_005fmpi_005fcleanup-356"></a>
which is much like the <code>fftw_cleanup()</code> function except that it
also gets rid of FFTW's MPI-related data. You must <em>not</em> execute
any previously created plans after calling this function.
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