I just finished my math undergraduate program, and the class that I enjoyed most that you don't seem to have studied at all is topology. We used Munkres, which seems to be pretty standard as far as undergrad topology is concerned, and if you're interested in getting into some more advanced pure math topics topology is super useful. I also found that learning the topological definitions of common properties like continuity to be very insightful and often much more natural than the definitions usually given in an analysis class.
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I just finished my math undergraduate program, and the class that I enjoyed most that you don't seem to have studied at all is topology. We used Munkres, which seems to be pretty standard as far as undergrad topology is concerned, and if you're interested in getting into some more advanced pure math topics topology is super useful. I also found that learning the topological definitions of common properties like continuity to be very insightful and often much more natural than the definitions usually given in an analysis class.
You are right, I haven't studied topology at all. I have heard the word before, but I don't know what it is. I'll look into it, thanks!