FFT of the average vs average of the FFT
28 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Hello everyone,
I've a (probably naive and simple question):
I've a NxM matrix (S): N measures, with M data point
I do the average along N and than compute the FFT =>
A = FFT(mean(S) )
on the other side I do first the FFT of each of the N measure and than I average along N:
B = mean(FFT(S))
Now my A and B are different, and look like that the average and FFT are not abelian operations.
However from my memory using the linearity of the Fourier transform and the Fubini-Tonelli theorem (you can switch sum and integral if every integral is finite) A and B should be the same.
I mean: the fourier transform of the average of a set of signals should be the average of the fourier transforms of eahc signals
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/963290/image.png)
Am I missing something? Should I expect my A and B to be the same? And if not, why?
Thanks in advance
0 Kommentare
Siehe auch
Kategorien
Mehr zu Fourier Analysis and Filtering finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!