Hi, yes, you are definitely correct about the maths! But, does it have to be so inpenetrable? About 30 years ago DSP chips appeared and I was designing the boards but they looked interesting so started to learn about signal processing. I never really got anywhere. Not so long ago I bought the book by Abbott, phew, Fourier transform with a pencil and ruler!!!!! But why couldn't all these wonderful DSP teaching texts have done the same thing?

I have found that if you want to learn something then any book published after the mid 1960s won't be of any help, they seem to have just swallowed formula and regurgitated them. Just buy lots and lots of books, they all have something of interest in but occasionally you hit a masterpiece, your Korn books for example. My interest was electromagnetism so not really relevant here, did end up with about 200 books though!

Yes, how many of the sine cosine pots did you want? Not certain how many I have got, in the middle of a serious sort out.