Originally Posted by

**maddas**

So my question, I guess, is: can we talk about frequency and wavelength for non-sinusoids, at least for a large class of "wavelike" functions? Why are infintesimal tools used so heavily in calculus but not in signal processing? How can we control oscillation and to what extent does "badness" arise from high oscillation? Is there any useful notion of instananeous frequency? If not, why is it not useful (does it not control the function as much as I think it does?)? Are there any books developing any of these ideas? Are function spaces like BMO what I'm thinking of? Is Fourier analysis what I'm thinking of? Did I make any sense?

(I'm posting this in the analysis forum but I don't know where it belongs really...)