[Numpy-discussion] fft trouble

Gabriel gbsuar@gmail....
Tue Nov 3 21:29:32 CST 2009


Yes!!! it was... I didn't realize.
Thank you very much

2009/11/3 Raspaud Martin <martin.raspaud@smhi.se>

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> Gabriel wrote:
> > Hi it`s my first time.
> >
> > I have a trouble whit fft.
> > For example:
> > s = sin(wt)
> >
> > f = abs(fft(s))
> >
> > In f I have the module the fft(s) which should be equal to 1 for w but
> > it's 1000 for w. All values is multiplied by 1000.
> >
> > Someone know why?
>
> Hi,
>
> I don’t know if this is numpy related, but I know a little bit about fft
> in general, and it looks like you did not normalize the result.
>
> The documentation does not specify that the resulting array is
> normalized, so you should do :
>
> s = sin(wt)
> f = abs(fft(s) / len(s))
>
> I guess your wt has a length of 1000 ?
>
> Regards,
>
> Martin
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-- 
Gabriel

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