@noiob @halcy well tbf both are really cool

@pcy @halcy there's so much cool maths I don't think I could pick a favorite

@noiob @halcy very true

@pcy @noiob @halcy IMO the FFT is particularly cool, because it's what caused the switchover from "ugh, i want to do some frequency-based stuff but fourier transform is so slow, maybe i can find a way to do it in time domain" to the modern-day "fourier transform all the things!"

@pcy @noiob @halcy specifically the generic form of the fast fourier transform as published by James Cooley and John Tukey in 1965… well after transistor-based programmable electronic computers were commercially available.

You can see a crossover in audio compression where up to the 70s or so everyone was doing differential stuff and linear prediction, and afterwards people started using DCT (calculated using an FFT-derived method)