e same way, but were
not documented.)
</p>
<p>In FFTW 2, there were <code>fftw_malloc_hook</code> and <code>fftw_free_hook</code>
functions that allowed the user to replace FFTW&rsquo;s memory-allocation
routines (e.g. to implement different error-handling, since by default
FFTW prints an error message and calls <code>exit</code> to abort the program
if <code>malloc</code> returns <code>NULL</code>).  These hooks are not supported in
FFTW 3; those few users who require this functionality can just
directly m