There isn't a listing for his MATH 171 class but I'll leave this here.

TA (Kadar K.) was great, I went to his office hours all the time both to confirm HW answers and talk about other math and ML stuff. Though Prof himself limits his office hours to a 15 minute zoom call. Pretty slow-paced course, lots of time to go off on tangents, tell jokes, and throw shade at the worst students. But that gives Prof time to make absolutely sure everyone understands every concept, which I like. Interesting concepts with many computations and not many super rigorous proofs. He writes hard tests but makes sure the class gets a B+ average, which I also like because it becomes less about being super careful and more about understanding things. No extra credit, but gives reasonable partial credit. You can't drop exams, but you can drop a homework (which the other TA (forgot her name) graded kind of brutally). I also appreciate how I've talked to prof for 15+ minutes after class before and he still tries to help, and also he keeps his email open to students.

Unless you're pretty capable, you'll have to show up to class, but you can be late. He gives you an oral exam if you don't show up to enough randomly selected ends-of-classes (like half of them or less), and you lose 10% on your final (worth 50%) if you do poorly on that, but that bar is set pretty low. That could also end up as a double-punishment since your homework average is then capped at 1.5 times your final exam score. If you can't show up, you could dig through the free textbook or make some friends to try learning everything for the oral and written exams. Unfortunately that's a bit hard when there isn't a Piazza or Discord for the class.

Anyway, that class was fun. I'll miss Prof Yin a lot.