Physicists, computer scientists, engineers, (and many others) all study maths subjects beside their fields, because maths plays a critical role to understand such fields and to achieve required accuracy of calculations needed.
But, what are the courses that are necessary to understand mathematics itself?
Logic course could be one of them to understand and agree with the mathematical proofs.
I am not specifying any branch of maths, but in general, I believe there must be some important course that play a significant role to understand maths (not only proofs).
I wish you can suggest me.
Your help would be appreciated. Thanks.