[Numpy-discussion] calcul of phase (dividing by 0)
Andrea Riciputi
ariciputi at pito.com
Thu Feb 10 06:42:53 CST 2005
Why not arctan2(ff.imag, ff.real)?
Cheers,
Andrea.
On 10 Feb 2005, at 15:16, Jean-Luc Menut wrote:
> Hello,
>
> I'm want to have the modulus and the phase of a fourier transform of
> 2D array, so I use the numarray FFT to compute the FT of the array
> (let's call it ff) and I use abs(ff) for the modulus and
> atan(ff.imag/ff.real) for the phase.
>
> My problem comes when ff.real = 0, I have either inf or nan as result
> (which is perfectly good and useful). I looking for a function which
> replace atan(ff.imag/ff.real) by 0 when ff.real is 0.
>
> I'm currently using a loop, and I think it's not very good (I call
> this function very often). Since the determination of the phase is
> something really useful and often used, I think there is probably a
> lot of people who had the same problem.
>
> So what solutions do you use?
>
> Thanks,
>
> Jean-Luc Menut
>
>
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