So i'm taking a class that's actually called techniques of theoretical physics. Basically, its applying math to physics. Topics we cover are: Vector Calc, Diff EQ, Linear Alg, and Fourier series, (i think, thats from memory.) problem is, the professor is insanely fast, the material is hard, and i don't have access to a book yet, (he failed to put on on reserve, and its currently checked out, and i don't have the funds for books this semester...) So, i'm already falling pretty badly behind, and i really need to catch up. We've been going over divs and curls and line and surface integrals and now we're on the delta function. Plus we've been working in all sorts of coordinate systems that i'm not used to. So i need to find a comprehensive but understandable resource to try and learn the material from. I've been to a few online websites, but i've had a hard time being able to follow them. Any recommendations?