What engineering major  in undergraduate is compatible for taking a master in Mathematics? Short question: What the engineering major in undergraduate is compatible for taking a master in Mathematics?
 A: Short answer: electrical engineering, computer science.
Specifically, computer science focuses on discrete mathematics and algorithms in general, such as graph theory, computational geometry, combinatorics, number theory, game theory, also some topics in operations research like linear programming, convex optimization. There is another branch called computational mathematics, which emphasizes on numerical analysis. All of these have a lot of applications in computer science. If you are interested in both theory and practice, you should go for computer science.
A: This completely depends on what you mean.  Do you mean, will I be ready for graduate school in mathematics because I already have a degree in electrical engineering?  The answer is probably no.  The math you take in electrical engineering doesn't even amount to a math minor probably, let alone a math major.  Did you take a course on introduction to proofs?  Did you take abstract algebra?  Did you take real analysis?  Maybe you took the calculus sequence and linear algebra and differential equations, and maybe you used some complex analysis.  So, you're still a few classes away from being ready for a masters in mathematics.  If your question is simply, which one will get you closest to being ready, maybe electrical engineering or computer engineering would do the trick.  But, that does not mean that either one would have actually prepared you enough.  You're just closer than if you had done a different type of engineering.
