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Topic: Why does the default fft data number change for a identification data
Replies: 1   Last Post: Apr 4, 2013 3:11 PM

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Polly Onymy

Posts: 7
Registered: 4/28/13
Re: Why does the default fft data number change for a
identification data

Posted: Apr 4, 2013 3:11 PM
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On Thu, 04 Apr 2013 09:46:14 -0700, fl wrote:

> I try to run a snippnet of identification toolbox user guide:
> % Load input u2 and output y2 load dryer2;
> % Create iddata object tdata = iddata(y2,u2,0.08);
> % Take the Fourier transform of the data % transforming it to frequency
> domain fdata = fft(tdata)
> % Get property values of data get(fdata)
> The length of tdata is 1000 while the length of fdata is 501. I have
> check function fft and I do not find anything can explain it to me.
> Could you help me on this question?

What did you notice about workspace arrays when you copied, pasted, and ran one of the example programs in the
section "Help -> Matlab -> Mathematics -> Fourier Analysis and Filtering"?

> Thanks,

for what?

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