[Tutor] fourier transform
Christian Meesters
meesters at uni-mainz.de
Tue Aug 2 18:52:11 CEST 2005
Hi
Pawel Kraszewski wrote:
> 4. The answer is symmetrical - usually you take only half of it. I
> don't
> remember the exact difference between the halves, but you may find it
> in any
> article on FFT.
The real part is identical the imaginary part has the opposite sign
("same amplitude, opposite phase").
Jeff Peery wrote:
> thanks for the help. I think I'm understanding this a bit better.
> although I still don't completely understand the output. here is an
> example... for the input I have 1024 samples taken from a 1 Hz square
> wave with amplitude = 1. for the output I would expect an infinite
> number of frequencies. the output from FFT.fft(myData).real is this:
>
> .
> .
> .
> -0.498 1
> 0.0 2
> -0.498 3
> 0.0 4
> -0.498 5
> 0.0 6
> -0.498 7
> 0.0 8
Frankly, I don't understand this. After your description I thought your
input is like "array([0, 1, 0, ..., 1, 0, 1])". But this can't be.
Could you show us how exactly your input array looks like?
And how do we have to read your output? Is this a 1d-array? What do the
two numbers per line mean?
Cheers
Christian
PS Sorry for the late reply.
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