Arrays and FFTW

Hello! I'm a PGSQL newbie. I have installed postgres only a
few days ago in the attempt to use it to solve a specific
problem.

I am using (trying to...) PGSQL to store a database of
digital signals. Each signal is a sequence of (signal_id,
timestamp, double) tuples. I've managed to write resampling
alogrithms in pl/pgsql, and I don't think it would be hard
to write autoregressive filters. However, now I'm confronted
with the need to compute the power spectra of my signals. I
would like to use FFTW, which is lightning fast on my
machine. Has anyone already written FFTW bindings for
PostgreSQL?

If I have to write the code myself, I would need to create a
database function calling code from a C module. Such code
would have to operate on real and complex float arrays. I
understand how I could use a pl/pgsql function to create a
new table where each signal is stored as a (signal_id,
double array) tuple, but how am I supposed to pass such
arrays to a C function? How are postgres arrays actually
implemented in memory? In short, I need someone to get me
started on writing an FFTW binding for pgsql, in none is
already available.

Thank you in advance for any help you can give me. And
double thumbs up to the developers: running PostgreSQL for
the first time is an epiphanic experience. I want to study
the ins and outs of it rapidly so that, hopefully, in a
while, I will be able to contribute to the pgsql project.

Alex Baretta