I'm currently studying economics and am interested in getting into economic research. I'm aware of how math based economics research is. I have done some 1st math courses (probability, linear algebra, univariate calculus and discrete math), a 2nd year course in probability and have done/am going to do multiple courses in econometrics. However, I would like to learn the remaining math needed in my own time. When looking at advice pages on this topic people usually say some combination of needing: linear algebra, multivariable calculus, real analysis and probability. However, I'm hesitant to learn all of these topics from text books as I feel like I would learn a large number of topics that aren't used in economics. For example, in multivariable calculus divergence doesn't seem that applicable to economics. I feel that my time could be spend more productively going deep in the concepts that come up a lot in economics. I was wondering whether someone would be able to collate a list of all the useful concepts needed in each of these subjects in the format:
Multivariable calculus:
- Langrangian
- Hessian matrix
- etc
Thanks in advance.