Fourier transforms of power of a function

1. Dec 18, 2009

sumesh.pt

I am not able to comprehend this :
/int dx (df(x)/dx)^2 = \sum (q^2 F(q)^2 where F(q) is the fourier transform of f(x).

Can some one throw light?
thanks.

2. Dec 18, 2009

cepheid

Staff Emeritus
I'm typesetting your attempt at LaTeX properly so that I can read it:

3. Dec 18, 2009

cepheid

Staff Emeritus
I don't think that the equation, as it stands, is true. It's also not very clear because you haven't specified what range you are summing over on the right-hand side. If you told me that the Fourier transform of what was on the left-hand side was equal to the right-hand side, I might believe it. Because you mentioned the power of signal, I suspect that this might be a combination of Parseval's relation for Fourier transforms (or series?) and the differentiation property of said transform (or series).

4. Dec 19, 2009