Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

Fourier transform and maximum

Tags:

algorithm

fft

Is there a way to compute efficiently the Fourier transform of the max of two functions (f,g), knowing their Fourier transform?

like image 704
fulmicoton Avatar asked Mar 01 '10 13:03

fulmicoton


People also ask

What is Fourier transform formula?

As T→∞, 1/T=ω0/2π. Since ω0 is very small (as T gets large, replace it by the quantity dω). As before, we write ω=nω0 and X(ω)=Tcn. A little work (and replacing the sum by an integral) yields the synthesis equation of the Fourier Transform.

What is meant by Fourier transform?

The Fourier transform is a type of mathematical function that splits a waveform, which is a time function, into the type of frequencies that it is made of. The result generated by the Fourier transform is always a complex-valued frequency function.

What is Fourier transform and its properties?

Fourier Transform: Fourier transform is the input tool that is used to decompose an image into its sine and cosine components. Properties of Fourier Transform: Linearity: Addition of two functions corresponding to the addition of the two frequency spectrum is called the linearity.

What is Fourier transform example?

The Fourier transform is commonly used to convert a signal in the time spectrum to a frequency spectrum. Examples of time spectra are sound waves, electricity, mechanical vibrations etc. The figure below shows 0,25 seconds of Kendrick's tune. As can clearly be seen it looks like a wave with different frequencies.


2 Answers

I doubt it. The Fourier transform of max(f, g) can be computed efficiently if and only if the Fourier transform of |f| can be computed efficiently. (Because max(f,g) = (f+g+|f-g|)/2.)

But there seems to be no relationship between F{f} and F{|f|}...

like image 114
kennytm Avatar answered Oct 03 '22 08:10

kennytm


Assuming you mean the max at each point, and since max is a non-linear operation, there is not going to be any way to do this. You would need to do the max operation in the time domain and then perform the Fourier transform.

like image 36
Paul R Avatar answered Oct 03 '22 06:10

Paul R