Physical meaning of ifftshift?

[vivek.iitd]

I am using ifftshift function in matlab, mathematically it does the following functions

If M is a row matrix:
M = 1 2 3 4 5 6 7 8;

then ifftshift(M) = 5 6 7 8 1 2 3 4, i.e. it replaces first half with the second half. Although how can be explain this function physically?

 

[AlephZero]

The ifftshift function undoes the effect of fftshift function.

The purpose of fftshift is to put the zero frequency in the center of the frequency spectrum from an FFT, rather than at the left hand end. In other words, you want to interpret the FFT as covering a frequency range from -f/2 to +f/2, not from 0 to f.

None of this has much "phyiscal" significance, but it's useful for producing plots in the form you want to see them.

 

[vivek.iitd]

Okay it is just to arrange frequencies. Thank you.