David Billinghurst wrote:
> jmm wrote:
>> Do someone of you know if there exist a maxima package to calculate
>> fft for list of length # of powers of two? I need it for a calculus.
>> It isn't very difficult to write, but if there exist yet, it has
>> no-sense to waste effort to rewrite it.
> maxima has an fft() function. It is documented in the manual.
>
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1. the fft routine in Maxima requires power-of-2 size.
2. most fft applications are somewhat flexible in that you can round up
to the nearest power of 2.
3. if you are not in a hurry, but just need a discrete fourier
transform, an O(n^2) one is just one line.
4. if you need random size ffts and very fast, I have, quite by
coincidence, set up links between the FFTW package
and Lisp. This allows any size and may be 20X faster than Maxima's.
Downside: I've only debugged the
code for Allegro common lisp (free), and someone else will have to
duplicate the foreign-function interface
(about 1/2 page?) for any other lisp.
http://www.cs.berkeley.edu/~fateman/cheby/fftw.lisp
RJf