As a former bookseller and math student, I want to second your nomination of Introduction to Algorithms--I wish my copy weren't hundreds of miles away--and also want to quibble with what you said about O(f(n)).

It is math.¹

A lot of interesting math--especially math of interest to computing science--is done through approximation rather than turning out exact answers. I, too, used to look down on that as not real math, but I was wrong.

Now that that's out of my system, here's a little more good advice from my bookseller self:

Don't buy a current used textbook. Instead, look for an old edition. Trust me on this--little has changed in calculus and trig in the last century or so--and old texts are worthless to the college bookstore. If they have any, they probably have them out on the dollar a sack sale table.

If they don't have them out there, ask the textbook manager or try a used non-textbook store, and don't pay over five bucks--ten at the most--or ask around for a freebie at the math department at the local colleges.

There is a very good chance that your math teacher can't help you--mine couldn't (but he was a good track coach, I'm told), when I took on calculus in tenth grade. What he did do for me (since he couldn't explain how the Chain Rule was derived) was tell me that if I'd sit in class and quietly study calculus, he'd grade me just on my text scores (i.e., no algebra homework). That I wasn't supposed to bug him with calculus questions went unsaid.

This doesn't mean that your teacher won't be able to help you directly with the material--more likely she can than can't, but it's not a slam dunk--but it does mean that she can surely help you in some manner. However, the degree of help you get in this optional exercise is more than directly proportional to the politeness and respect with which you approach her. Only a saint (and I've benefited from a couple) will help a hateful student.

Let's see, what else? Oh, yeah--for an introductory text on discrete math, I like Discrete Mathematics by Richard Johnsonbaugh. It's in its fourth edition, so look for an old edition, and again, don't go over ten bucks.

Good luck, and have fun!

adamsj

They laughed at Joan of Arc, but she went right ahead and built it. --Gracie Allen

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1. I'm jealous of tadman, since, while I would agree with him that the ideas in the various O-notations are simpler than the ideas in multi-variable calculus, I found them harder to learn and prove.