BetterExplained is a really great resource for any math that they cover. It's the kind of explanations of math that I think Khan Academy was originally going for but lately has seemed to drop in quality.

I really hope math teachers and professors can start to move more towards this kind of "intuition" training as opposed to the arbitrary instruction found in most textbooks. It won't get as good of grades on tests but it's much more helpful in a students long term to have "knowledge" as opposed to "instruction".

It's been frustrating because my high school Calculus teachers were really good about teaching in that way. In college the teachers have been really dismal at reaching any kind of usefulness. They've long abandoned any kind of real understanding for the short term benefit of "just remember this formula" on (their own) tests.

The style of the article reminds me of my all-time favorite book about DSP, by Richard G Lyons: http://www.amazon.com/Understanding-Digital-Signal-Processin...

One thing I found interesting:

You can view the FT as a method that fits exponentials. You can even generalize this idea and then you have the Prony method.