 as equally as possible.
</p>
<p>For a multi-dimensional complex DFT, FFTW can divide the problem
equally among the processes if: (i) the <em>first</em> dimension
<code>n0</code> is divisible by <em>P</em>; and (ii), the <em>product</em> of
the subsequent dimensions is divisible by <em>P</em>.  (For the advanced
interface, where you can specify multiple simultaneous transforms via
some &ldquo;vector&rdquo; length <code>howmany</code>, a factor of <code>howmany</code> is
included in the product of the subseq