[SciPy-user] Difference between ffts?
Collin Day
dcday137@gmail....
Mon Oct 13 22:36:16 CDT 2008
Hi all,
I have looked around, but can't seem to find an answer. I have been
trying the following (according to the Getting started page -
http://www.scipy.org/Getting_Started)
from scipy import *
a=zeros(1000)
a[:100]=1
b=fft(a)
plot(abs(b))
and I get what you would expect - the abs. value of a sinc function
rect(x) ->F-> sinc(Frequency)
now, if I try the Scipy.fftpack
import scipy.fftapck as S
c=S.fft(a)
figure()
plot(abs(c))
I get something I would expect if I did a FFT on a sine function (kind
of like dual spikes equally spaced)
I do see there is a difference in the packing or how the fft output is
represented. How do you plot the data from fftpack so that it looks
correct? Should I even bother?
Thanks for any help!
-Collin
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