p>
</div>
<hr>
<a name="Upgrading-from-FFTW-version-2-1"></a>
<h2 class="chapter">9 Upgrading from FFTW version 2</h2>

<p>In this chapter, we outline the process for updating codes designed for
the older FFTW 2 interface to work with FFTW 3.  The interface for FFTW
3 is not backwards-compatible with the interface for FFTW 2 and earlier
versions; codes written to use those versions will fail to link with
FFTW 3.  Nor is it possible to write &ldquo;compatibility wrappers&rdquo; to
bridge the gap (at least no