Learn advanced mathematics, linear algebra, probability theory first, and then learn advanced linear algebra (or matrix theory), ordinary differential equations, numerical calculation methods, random processes, and mathematical equations.

Take three basic math courses first, and then read only professional books. To sum up, three basic subjects must be solid, and five professional subjects must be able to learn.

The three basic subjects don't need to be in order. It doesn't matter which one you look at first. Professional courses must begin after reading the basic courses, first look at matrix theory, numerical calculation methods, stochastic processes, in no particular order, then ordinary differential equations, and finally mathematical equations.

Pay attention to the three basic subjects is the most important.