t efficiently), because FFTW 3 has different
semantics from previous versions.  However, upgrading should be a
straightforward process because the data formats are identical and the
overall style of planning/execution is essentially the same.
</p>
<p>Unlike FFTW 2, there are no separate header files for real and complex
transforms (or even for different precisions) in FFTW 3; all interfaces
are defined in the <code>&lt;fftw3.h&gt;</code> header file.
</p>
<a name="Numeric-Types"></a>
<h3 class="heading">Num