Edit: Calling it a mini-TAOCP of most of the maths needed for physics/EE work might be a bit of a stretch, but I've yet to see another maths text that does better as a highly readable, self-contained and compact reference.
Edit2: I moved house once and thought I'd lost my copy from university. I eventually found it, and yes, I have two copies... It's that important to me for brushing off the things I've forgotten :)
The book has many worked examples, and the extensive end-of-section questions have the answers in the back of the book (for every 2nd question). This means you can learn by "reading then doing", and see if you have got the answers right - something many textbooks lack.
When I try to learn from other technical books, I often find myself thinking "I wish they'd written this in the same style as Boas".
It got me wondering...suppose there were a website for autodidacts in math and similar topics? Something where people could post and discuss their answers to exercises. It'd solve the whole problem.
Would textbook publishers sue?
Or they could just trust the students. At my university the honor code such a big deal that they let students take closed-book tests at home.
Maybe DennisP's idea could do the same thing - only post answers to the odd-numbered questions. Of course, DennisP's scheme would only work for books that actually have decent end-of-section questions, unless people made up extra questions as well ...
* I say much rather than most or all since it's focused on asymptotics, recurrences, number theory. Modern theoretical Computer Science draws on a much wider variety of mathematical methods.