[Scilab-users] Re : fftshift and ifftshift are way too different

[Antoine Monmayrant]

Le 06/11/2018 à 10:52, Samuel Gougeon a écrit :
> Le 10/10/2018 à 12:39, amonmayr at laas.fr a écrit :
>> Le 10/10/2018 à 08:47, Samuel Gougeon a écrit :
>>> Le 09/10/2018 à 21:52, antoine monmayrant a écrit :
>>>> Hello Samuel,
>>>>
>>>> Sorry I might not have made myself clear: fft and fftshift provide 
>>>> the ability to perform transform along only one of the dimensions 
>>>> of a multidimensional array.
>>>> Something like S(x,y,z) --[FFT along 3rd dim]--> 
>>>> ffthift(ffft(S(x,y,z), -1,3),3)=Ŝ(x,y,kz).
>>>> In that case, you need to perform fft and eventually fftshift along 
>>>> only the dimension of the transform.
>>>> ifftshift should also provide the same possibility to perform the 
>>>> inverse transform: Ŝ(x,y,kz) --[IFFT along 3rd dim]--> 
>>>> iffthift(ffft(Ŝ(x,y,kz), +1,3),3)=S(x,y,z).
>>>>
>>>> This is a basic signal processing requirement in my field.
>>>
>>> Hello Antoine,
>>>
>>> Yes, you are right: in case of directional FFT and odd number of 
>>> elements along the chosen direction, ifftshift can't presently be used.
>>> Could you please post the same remark on bugzilla? This bug/wish is 
>>> not yet reported.
>> Done: http://bugzilla.scilab.org/show_bug.cgi?id=15799
>
> This complementary feature is now implemented and proposed for Scilab 
> 6.0.2 there <https://codereview.scilab.org/20573>.
Nice!
>
> BR
> Samuel
>
>
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