This is my second quarter with Prof Hsu- I took 31A with her last quarter. She's a fantastic lecturer and professor, and I honestly enjoyed taking these classes even though I wasn't the best at math in high school. She's super fair in terms of content on the midterms: the first one had a lower average at around 60ish (most people had issues with timing instead of actual content), while the second had an average around the mid-70s (less questions after we gave her feedback) if I remember correctly. She 'curved' by adding a 12 point extra credit problem to the final using M1 content. Be warned: we had a take-home final this quarter due to the virus and campus shutdown, but her finals are much harder in terms of content and application compared to the midterms.

A few things: she added a quiz section to this quarter: there's four in total, with the lowest grade dropped. It's two questions, done in discussion, that are pulled from the previous week's homework, which you don't have to turn in. Lowest homework is dropped as well. She offers two different grading schemes that allow you to use the max of your two midterms or the average of the two.

All in all, I couldn't recommend taking her classes more. She's always super clear and helpful, and I loved learning from her.

I love Dr. Hsu, but here class is unreasonably difficult. I genuinely enjoyed going to her class, even though I dislike math and it was an 8 AM class. She is really nice, sweet, and helpful. Sometimes, she's funny too. The homework is harder than the class, but that helps me learn. The only problem with this class is the fact that the tests are really hard and she doesn't curve. Our first midterm had an 82 average, which was great. But the final and midterm 2 were around 72%, I don't remember exactly, and she didn't curve the tests. The final was by far the hardest test I've ever taken, and without the curve I went from having a B+ in the class before the final to a C+. If you really want to learn take Dr. Hsu, if math isn't your strong suit and you just care about the grade take an easier professor.

Prof. Hsu is a really good teacher and individual. She focuses a lot on getting the mathematical concepts across to her students and wants them to really understand the concepts instead of just applying them blindly. She puts a great deal of efforts in making sure her students understand her stuffs and is very helpful. She really cares for her student. Her notes are really useful for the tests although that does not make the tests any easier. Overall, she’s a really good teacher and definitely will pick her again to teach Maths in the future if possible.

Her exams are difficult and focus on conceptual questions.

Chi-Yun Hsu is not just my math professor; she is my role model. She teaches everything very intuitively and her tests aren't too hard as long as you keep up with homework. You don't even need to attend office hours or anything to get an A. She's a really good professor, and she makes a new worksheet for every class, which makes for easy revision at the end of the year. I LOVE HSU <3

I think she deserves a higher rating for 31B. This class is an awkward class that usually took by nonmath majors and by math majors like me who take it for various wired reasons. I can imagine for an upper div serious math class Chiyun will have a much much higher rating.

She is honestly one of the best teachers I have ever had. Disclaimer, I am TERRIBLE at math and I don't know how I finessed an A. But that's not why I love this woman, I got a C+ in her class in 31A and decided to take her again, cause that's how great she is.

She is a phenomenal professor and lecturer. Her lecturers are engaging, and she MAKES a worksheet for us every class so we have the problems she is going to do and the concepts we are going to learn. The lecture is pretty easy to follow, but they're really conceptual, which is fitting cause her tests are like that too. The homework is lengthy, and difficult, but if you do it you will do well in the class. It is also graded, so it depends if you REALLY do it or if you find the answers online.

This quarter she added quizzes, which test the topics on the homework from the previous week. These helped my grade, and are fair. Take the discussion on Thursday so you can find out what topics she tested on Tuesday. They aren't the same questions for each discussion, but the same topics from the HW.

The tests in this class are ROUGH. Midterm 1 had a 60 average, and the second one was around 75. I really studied for the second one, so I did fine on that one. The first one was impossible for me, and I felt really underprepared.

With Chi-Yun you have to know your stuff to do well. There's not much partial credit given, and small mistakes will cause big deductions in the score.

Cause of COVID, we took a take home final. Which was a lot harder than the test in class, but we had 24 hours, so it was fine. At first, I got a B on the final. Then, we get an email from her telling us that people posted a couple of the final questions on Chegg or something like that, so in order to not penalize people who didn't cheat, she'll mark the questions she found correct for everyone. This way, I ended up getting a 100 on the final.

With the grading scheme (one uses both midterms and one only uses one of them), I was able to get an A in the class. There's also extra credit, but it's only 1%.

Chi-Yun is very easy to reach outside of class, she is very kind, and if you do well in her class you have to really understand the content. The only problem with her is that she's so smart (I didn't feel this with any of my other professors here), that she skips steps or stuff seems obvious to her. But, she's always willing to help you out if you get lost in class.

I think Chi-Yun is great, and going to her class was something I was excited for, which was weird cause I hate math. Trust me, take her class. She's the best.

I like professor Hsu. She's really nice and caring, and I like her positive energy. I wish I had the chance to take her in person. Her class and lectures are very organized. The pacing of the class was good because we were able to cover everything she wanted to from the syllabus, though we did deviate from the syllabus a little since she wanted to talk about Bitcoin $$$. She's alright during lecture, but sometimes I'll get lost since I have no idea what she's talking about. And she's extremely confusing when she's doing a proof. One time she did a proof from the homework during office hours and I copied her proof onto my homework and when my homework got graded, I lost points since there were flaws in the proof. :( Perhaps I would avoid taking a proofs class with her if you can. It helps to read the textbook because it's sometimes better than her notes.
Hsu takes into consideration feedback from the students. We filled out two surveys during the quarter. At first, the workload was a little heavy, but someone complained about the workload on Piazza so the homework assignments gradually got cut down to about 3-5 problems. Most of the problems will come from the textbook. There will be some problems with tedious calculations like calculate 23^3 * 19^5 * 11^4 (mod 97). We're required to do some problems by hand, and some problems using Sage. She'll provide the Sage instructions on the homework but it's usually straightforward. You don't need coding experience to do well in this class. We had 9 homework assignments this quarter (1 homework / week... we had a homework due during finals week :( ). I appreciate that she published the homework solutions to every assignment.
Her exams are straightforward, given the online setting. This is probably my only online math class where I thought all the exams were possible to complete in the suggested time of 1 hour for the midterm and 3 hours for the final. Both of the midterms consisted of about 3 multiple choice questions and 2-3 fill in the blank which are the conceptual questions that I usually would get incorrect. The rest of the exam is mostly 4 computational questions, and 1 proof question. The proof question is alright, and it's easier than the proofs from the homeworks. The averages on the midterms were in the 90s, which is to be expected since the questions were mostly computational. I would imagine the exams to be harder in person since there's a lot of algorithms to memorize and I don't know if she'll let you use your notes. The algorithms aren't hard to perform, but it might be hard to memorize all the steps. I scored well on the exams but I think I would get a much lower score if I had to take the exams in person because I would not remember all the algorithms and cryptosystems. If you are good at memorization, then you will do well when taking the in-person exams.
I don't think it's absolutely necessary to have taken 115a before this class. We did a section on lattices which did involve linear algebra, but if you have taken 33a, you should be fine. However, I think you should have some exposure to proofs. Some homeworks will have 1-3 proofs in it, and you should expect a proof on the exams. Also maybe it could help to have exposure to algebra (110a) but it's not necessary since this class doesn't assume any algebra knowledge. I haven't taken 110a and I still did well. You should expect to do lots of modular arithmetic in this class. At times, this class felt more like a number theory/algebra class than a cryptography class. This class makes me bored sometimes but I would recommend this class if you have some interest in cryptography.

Okay, so I was extremely shocked at why I got a B in this class but I'm not complaining. Let's dive into the mechanics of this class (I'm sure most of you that are reading this right now have to take this class as a pre-requisite for your major)
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LECTURES
This is one of those classes where the lectures either work or don't work for you. She tends to focus on the concepts rather than the actual calculations and because of this, she always seems to rush through the material in a short fifty minute period. I can not tell you how many times I've come out of a lecture and was like "What the heck did I just learn?". She usually has a printed out worksheet for all the students, but she also puts them up on CCLE for those who prefer to take notes on their tablets or computers (although she doesn't put them up before every lecture so I recommend just getting one of the hard copies that she prints out for every lecture). The worksheets often contain notes and practice problems which are helpful to learn and understand the concepts.
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GRADING
If you took Math 31A/L, you would understand the general grading scheme. There are two grading schemes that you can use, but the one that is used for you personally is the one that gives you the highest score. The first grading scheme takes both of your midterms into account while the second grading scheme takes the HIGHEST of your two midterms and the final exam is weighted more heavily.
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HOMEWORK
On weeks that you have a quiz, there is homework assigned but you do NOT have to turn in (I'll dive into why you should do your homework even when you don't have to turn it in for credit later). I also find this pattern where she typically assigns a CRAZY amount of homework for the weeks that we have quizzes (I'm very very very salty about that one week where she assigned problems #1-50 on a week we had a quiz). On weeks that you don't have a quiz, you have roughly around 10-15 problems after each lecture that you have to submit before 9 pm on Sunday. Also, your lowest homework score will be dropped.
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QUIZZES
So back to why you should do your homework every week. Remember how I said that on weeks you have a quiz, you don't need to turn in your homework for credit? Well, she pulls questions from those homework problems and quiz you using them. The problems are EXACTLY the same so as long as you did your homework and remember the mechanics to solving those kinds of problems, you'll be fine. She only gives you two problems but it's out of ten points. Screw up one problem, you already got a 50% on that quiz (assuming you get the other problem correct). Also, your lowest quiz score is dropped.
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MIDTERMS
Where do I begin with this one? I hated every single exam she ever gave out. The average on the first midterm was 60%. A lot of people struggled with time management, but on the side, I personally struggled with both time management AND the problems on the midterm. The midterm was insanely difficult and tested us on some concepts that were never covered in class. The average on the second midterm was around 70-80% (can't remember), so there was definitely an improvement. I think she really took our first midterm evaluations seriously and lessened the difficulty and the number of problems on the second midterm. The structure of each midterm is usually as follows: five multiple-choice problems on the first page, followed by four-five short answer questions. There's always partial credit, so try your best to solve them.
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FINAL EXAM
Well, the situation that we had was certainly a unique one. Due to the rest of Winter Quarter 2020 and Finals Week being shifted online, she had to change her entire final exam. Following the structure of her midterms, I'm assuming that she would have also given us multiple choice and short answer questions that fit the general time frame of three hours. Instead, we had twenty multiple-choice questions, with one 12 point extra credit problem that would be added to our first midterm score to increase our score (since everyone scored so low).
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TAs
I sometimes found the TAs more helpful than the actual professor, but I think that's because the TAs work with smaller groups and are able to address more of the students' needs. If you can, go to your TA's office hours (or another TA's) for additional help. I went a few times and my TA was really helpful in helping me clear up some concepts.
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OFFICE HOURS/PROFESSOR'S CHARACTER
I personally didn't go to any of her office hours due to time conflicts, but she set aside about two-three hours for office hours each week. She usually reminds everyone in the beginning of each lecture when she's having office hours which is nice. Talking about her as a person generally, she's a nice professor and knows how to take critique (as demonstrated with how the average of the second midterm increasing). Also, I don't know if she has multiple of the same shirt, but I swear she wears the same shirt to every lecture. I just thought this was something funny I have to point out.
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EXTRA CREDIT
There's a few opportunities for extra credit but it's not much. There is a mid-quarter evaluation (after the first midterm), a final exam question, and the course evaluation that can be completed for some extra credit points.

I took Professor Hsu for 31A in Fall 2019, and she has undoubtedly bettered herself this Quarter for Math 31B and I loved her for how she made a point to learn from her evaluations whether from Fall or in Winter and better herself accordingly. Her Exams this Quarter were extremely simple. I am not great at Math, but I could complete her Midterm 1 in 35 minutes, and 2 in 20 minutes. For her Exams, solve each and every problem type, if not each and every problem.
Quizzes were also extremely simple and were from the questions she had assigned, no surprises, however, she assigned a large number of questions and that could be strenuous. The Homework was also problematic in that manner. Also, she added exercises in her syllabus that the other Math 31B Professor didn't do. In that sense, this Class can be intensive but it is extremely doable.
I will definitely recommend Professor Hsu if you are interested in learning. The level of easiness or difficulty in this Class depends on how much work you are willing to do outside her class. Do not let other reviews mislead you.