Problems with FFT and IFFT

[Sascha Berkenkamp]

Hi,

I've got a simple problem with the FFT and the IFFT function. 
I have got one function from matlab with both functions in it. But I
will not get the same results. So I started with testing on simple
task.
I have got a signal, transform it to the frequenz-domain and then I
transform it back to the time-domain.
Generally after transforming the signal shout be the same than the
input signal.
So my input signal (x) has no imag-part. So my retransformed signal
shoud have no imag-part, too.

fs = 0:0.1:10;
x = sin(2*pi*fs);
real(x)
imag(x)
X  = fft(x);
x2 = ifft(X); 
real(x)
imag(x)

But in my octave version (octave 2.1.72 from debian etch) the
imag-part of the retransformed signal is not zero.

When I put the code into matlab, everything is okay: no imag-part
after retransforming into the time-domain.

Sascha
-- 
GPG Key: http://homepages.hs-bremen.de/~sabe/gpg/SaschaBerkenkamp.gpg




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