I'm currently taking Precalculus in school, and I've been trying to get ahead by teaching myself Calculus, however I would also be interested in learning about other areas of mathematics (especially those which also relate to physics). Does anyone know of a specific division of mathematics that would be useful to know, and could possibly be self-taught? P.S. If the classes could not be self-taught I might be able to eventually take them at the local college next semester. Any textbook recommendations would also be helpful. Thank you.