Hello Physicsforums, Some of you may know me from my previous thread "how to thrive at an early age" and I have made much progress. Techniques of integration, differentiation, Newtonian dynamics, functions and limits, energy physics. I am also working on a system of trying to theoretically develop an orbit using the real values of the earth's mass, sun's mass, and the gravitational constant. Updating acceleration, velocity, x and y positions, for each time delta of one day. And using vectors, force equations, and equations to update the x and y comps of : position, velocity, and acceleration. Thank you for the advice. My birthday is coming up, and I am looking at getting some new textbooks. I have University Physics 13th Addition with Modern Physics, and Calculus 4th edition by Spivak. I was interested in getting a DE's textbook, linear algebra textbook, or maybe a trig textbook might be helpful. Suggestions are pleased. Thanks, Alex.