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

[Samuel Gougeon]

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>.

BR
Samuel

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