[Tutor] fourier transform

[Christian Meesters]

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.