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From: Dipasree Som on 1 Aug 2010 10:47
dru22(a)mindspring.com (dru shockley) wrote in message <34aa967c.7313103(a)news.mindspring.com>...
> I am trying to retrieve the signal back from an fft. According to the
> help files, ifft(fft(S)) should yield the signal S, with some rounding
> error. I have tried this numerous times, and get back a time series
> not even remotely resembling the original time series. The ifft is
> also yielding complex numbers as part of the time series, which were
> never part of the original signal. I have tried using the ifft only
> on the first have of the mirror fft spectrum, but this didn't correct
> the problem. Am I missing a step, or is this a bug in the ifft
> routine? Please help.
From: Dipasree Som on 1 Aug 2010 10:53
hi...
I am using matlab for first time. I want to retrieve back my original time domain signal using ifft and then plot it. Plotting is neglecting the small imaginary part, how can I avoid this and plot this imaginary part together?
From: Greg Heath on 1 Aug 2010 13:43
On Aug 1, 10:53 am, "Dipasree Som" <somdip...(a)gmail.com> wrote:
> hi...
> I am using matlab for first time. I want to retrieve back my original time domain signal using ifft and then plot it. Plotting is neglecting the small imaginary part, how can I avoid this and plot this imaginary part together?

In general, you could use a polar plot

figure
plot(x,'o')
xlabel('Real Part')
ylabel('Imaginary Part')

However, in this case you need different scales

figure
subplot(211)
plot(real(x))
subplot(212)
plot(imag(x))

I'll let you provide the details

Hope this helps.

Greg
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