[nSLUG] Possibly ignorant quest for simple FFT app
chamberlain2007 at gmail.com
Thu Jul 11 08:40:31 ADT 2013
+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
> 2. MATLAB - commercial, probably efficient and mature implementation
> 3. Octave -- free, open-source software similar to Matlab
> 4. Math::FFT Perl module -- free, open-source, seems efficient (based on a
> C implementation)
> There seems to be other implementations in Perl too. I am sure there must
> be at least one in Python.
> 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... 
> > 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. 
> > 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
> >  ...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.
> >  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/ ^^-^^
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