FML. A programmer just asked someone for advice on learning a bit about the signal processing/Fourier transforming that goes on around here, and that someone replied with “<long pause> Uh, I’d start with an undergrad linear systems book… Oppenheim and Schafer.” WORST ANSWER EVER, gods help the poor programmer.
My advice, likely too hastily offered to said programmer, with exhortations to ignore the previous advisor, turned out to be: (1) DFT chapter of “Scientist and Engineer’s Guide to Digital Signal Processing” (http://www.dspguide.com/CH8.PDF) and any subsequent chapters of interest (e.g., digital filters), and (2) Jack Schaedler’s “Circles, Sines, and Signals” explorable explanation (https://jackschaedler.github.io/circles-sines-signals/).
I was asked thoughtful question: why *not* read Oppenheim/Schaffer? Long-winded answer: we teach DSP the same *wrong* way we teach calculus: remember limits→derivatives→integrals? Well, Newton &co did integrals, then Cauchy &co did derivatives, and only then did Weierstrass &co nail down limits. High school calc reverses the history order and the usefulness order because it turns out that for integrals and derivatives to be rigorous, you need limits. This took us centuries to understand.
@22 Even calculus has its limits.
