eric Types</h3>

<p>The main difference in data types is that <code>fftw_complex</code> in FFTW 2
was defined as a <code>struct</code> with macros <code>c_re</code> and <code>c_im</code>
for accessing the real/imaginary parts.  (This is binary-compatible with
FFTW 3 on any machine except perhaps for some older Crays in single
precision.)  The equivalent macros for FFTW 3 are:
</p>
<div class="example">
<pre class="example">#define c_re(c) ((c)[0])
#define c_im(c) ((c)[1])
</pre></div>

<p>This does not work