Well, it doesn't cover any numerical analysis stuff, but what I usually recommend is Thinking in C++ Volume 1[^], which is also available on line[^] for free. I keep electronic copies of both volumes 1 and 2 on all of my computers, and I still consult them once in a while whenever I've been away from C++ for a while. Off hand I'd say just buy Volume 1 in dead-tree form; I don't think Volume 2 is quite as good, though it's still a useful reference.