ode> may
have certain advantages.  First of all, FFTW&rsquo;s routine can operate
in-place (<code>in == out</code>) whereas <code>MPI_Alltoall</code> can only
operate out-of-place.
<a name="index-in_002dplace-8"></a>
</p>

<p>Second, even for out-of-place plans, FFTW&rsquo;s routine may be faster,
especially if you need to perform the all-to-all communication many
times and can afford to use <code>FFTW_MEASURE</code> or
<code>FFTW_PATIENT</code>.  It should certainly be no slower, not including
the time to 