[nSLUG] Possibly ignorant quest for simple FFT app

Matthew FitzGerald-Chamberlain chamberlain2007 at gmail.com
Thu Jul 11 08:40:31 ADT 2013


Hi there,

+1 for Octave.  It's quite simple and very fast.  We used it extensively in
CSCI3162 and I was quite impressed with it.


On Thu, Jul 11, 2013 at 6:05 AM, Vlado Keselj <vlado at cs.dal.ca> wrote:

>
> I do not use FFT in practice, but if I were I would probably try:
>
> 1. GNU Scientificy Library -- free, open-source, likely efficient and
> mature
>
> http://www.gnu.org/software/gsl/manual/html_node/Fast-Fourier-Transforms.html
>
> 2. MATLAB - commercial, probably efficient and mature implementation
> http://www.mathworks.com/help/matlab/ref/fft.html
>
> 3. Octave -- free, open-source software similar to Matlab
> http://www.gnu.org/software/octave/doc/interpreter/Signal-Processing.html
>
> 4. Math::FFT Perl module -- free, open-source, seems efficient (based on a
> C implementation)
> http://search.cpan.org/~rkobes/Math-FFT-1.28/FFT.pm
>
> There seems to be other implementations in Perl too.  I am sure there must
> be at least one in Python.
>
> Regards,
> Vlado
>
>
> On Thu, 11 Jul 2013, Mike Spencer wrote:
>
> >
> > Summary: Looking for Fourier software simpleminded enough for me to be
> >          able to use it.
> >
> > I have a basic, possibly horribly distorted, idea of what a Fourier
> > transform does: You can make believe that:
> >
> >        +  any list of numbers are the amplitudes of one cycle of a
> >           hypothetical periodic function for even-spaced values of t,
> >           or that
> >
> >        +  any list of pairs of numbers are the t/amplitude values for
> >           one cycle of a hypothetical periodic function.
> >
> > And Fourier's insight says that any periodic function can be
> > represented as an infinite series of sums, vaguely like:
> >
> >        inf
> >       SIGMA  A sin(nt) + B cos(nt)   [where A & B are subscripted with n]
> >        n=1
> >
> > Yeah... [1]
> >
> > I'd like a simple command line program that will take an arbitrary
> > array of numbers or x/y number pairs and return the A & B coefficients
> > up to some modest max value for n.
> >
> > What I find on the net is one of:
> >
> >       +  FFT libraries for which I have to write surrounding code.
> >
> >       +  Interactive apps for serious DSP guys.
> >
> >       +  Apps for serious math weenies.
> >
> > all of which seem to start out assuming I know waayyy more than I do
> > (viz. very little) about the subject and don't promise to give me the
> > simple results sought.
> >
> > Purpose is to look for frequency patterns (if any) in putative random
> > numbers and also -- even more frivolously -- in the recordings made
> > from the mouse exercise-wheel tachometer. [2]
> >
> > I recall seeing graphic rendering of data from (what I took to be)
> > such a Fourier program on the screen of a guy who was doing hard-core
> > random number research for crypto.  I've lost track of him.
> >
> >
> > Maybe I'm so ignorant in this area that this is all too misguided for
> > a meaningful reply.  In that case you can just treat this as idle
> > entertainment on a slow day for the NSLUG list.
> >
> >
> > - Mike
> >
> >
> > [1] ...the real equation with discussion is in my old calculus
> >     textbook.  I'm weak on math and it doesn't get better with age.
> >     Not looking for a tutorial on Fourier math or FFT code.
> >
> > [2] Our mouse slacked off all winter but resumed using the wheel in
> >     the spring and I've logged over 30 evenings of running. Record is
> >     16,000+ turns of the wheel or about 4.8 miles in one evening.
> >     Visualizing the data requires an image 480x24000 pixels which
> >     gnuplot does nery nicely. :-)
> >
> > --
> > Michael Spencer                  Nova Scotia, Canada       .~.
> >                                                            /V\
> > mspencer at tallships.ca                                     /( )\
> > http://home.tallships.ca/mspencer/                        ^^-^^
> > _______________________________________________
> > nSLUG mailing list
> > nSLUG at nslug.ns.ca
> > http://nslug.ns.ca/mailman/listinfo/nslug
> >
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-- 
-Matthew FitzGerald-Chamberlain
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