Professor Richthammer's 31B was my first math class at UCLA so I didn't know what to expect. I thought he did a great job teaching up until around the 6th week of class. After that the material just gets more and more confounding and I think he tried his best to clarify it for us. Homework was a lot of work. Nine homework assignments due every Friday (drops lowest 2 if I remember correctly). He wrote his own problems (we never used the book) and so there were definitely challenging questions. He does his best to explain anything you don't understand if you go to OH or if you email him. The two midterms were pretty straightforward. I thought his grade curves were justified. The final was a monster. It was originally out of 120 or so but he set the total to 85. Even with that the class average was a 59%. It's a challenging class and the material isn't easy, especially the first time around, but he's overall a good professor. If you're planning on taking him for 31B, all I can say is make sure you do the homework in its entirety.