Prof. Sirbu was a great man and good teacher but the material was rather difficult to learn in depth in the little time available. The material isn't hard to learn, the problem is the amount of concepts that need to be learned each week. I actually did every homework and got a 10/10 on almost every single one, I even did the questions that weren't assigned, I thought I was on top of the material but somehow got a below average grade on midterm and final. The curve was pretty harsh. I had never received less than a B in any math class but ended up with a C in this one :(
I've never had a problem in the math dept. and Prof. Sirbu is no exception. He's very approachable and wasn't condescending. He will stray from necessary topics in class every once in a while, but he tells you what you need to know for the exams. He's average, but only in the best way.
This class was rather challenging, given the amount of material to be covered in the short amount of time alloted. Also, I'm not that good with math, but I still struggled with this class, even though I had already taken Calculus in high school. Miahai was a good instructor, and he knew the material well, but he basically just lectured to the class, barely taking time to help those who did not understand the material. Also, with his thick accent, it was sometimes hard to understand what he was getting at or saying, and the language barrier was also a problem in his understanding of the student's questions. Obviously, I would recommend taking calculus, but if you aren't that good in math and need more attention from the professor, you might want to look for a different instructor.
Overall Mihai is a good teacher. He's not spectacular but you learn the material well enough. He's pretty straight forward. I found it easier to pay attention to him than to read the book (book explanations are too long). It's true, you'll get bored listening to him but if you pay attention you'll pretty much learn whatever it is you need to do well on his tests. Always do the practice final exams and his practice problems to guarantee and A in his class. I think he's improved a lot in his teaching. I think the bad reviews are from people who doze off in class (which is semi easy to do unfortunately).
What a nice man. Professor Sirbu is thorough, moves at a reasonable pace, and explains concepts VERY clearly. If a concept is not clear, just ask him during class. Sometimes his in-class responses are limited (his classes are fairly content dense) but he is always willing to spend as much time as necessary during office hours to make sure you understand everything. Sirbu is very professional, so don't expect too many jokes during class. But, office hours reveal that he does have a sense of humor. Professors in the Math department tend to suck, but this man is very very good. Highly recommended for ODE. His Romanian accent is kind of funny. One downside, for some reason he loves greek symbols and uses them whenever he can. He used symbols I'd never seen before (one that literally looks like a squiggle!!!) Take ODE with this man, you'll like it!
This class has got to be the worse class I have ever taken. He lectures straight out of the book. The material is just ridiculous... honestly, you would NEVER do this kind of thing on the Street unless you have a PhD.
If you were disappointed with the mathematical shallowness of Financial Economics, then Discrete Time Models in Finance is for you. This class provides a very solid introduction to asset pricing in a way that is intuitive and mathematically rigorous. It does not require high level math nor previous experience with financial instruments. Everything is defined in very basic terms and taught from the ground up. In my opinion, this was the best class I have taken ever in my life. Mihai is a great teacher: he knows his stuff and can transmit it well. True, he is rather meek but this a virtue. He genuinely cares about his students as he is willing to re-teach material during office hours if he has to. As said in my review of his teaching ODE, Mihai is slightly on the generous side of fair when it comes to grading. But don't expect to slack off. Despite the elementary nature of the course, each concept builds on the previous one. The textbook, written by Steven Shreve -- a leader in the field of pricing theory -- was well chosen. It is well structured, simple, and weighs about a pound. Mihai takes care to follow it closely, which is another plus. If you miss class, you can always read the book. The course does go into continuous time theory near the end of the course, but not too deeply -- don't worry, it's not tested on the final. It gives you a glimpse into stochastic calculus and Ito's Formula. This is a must-take for people interested in becoming quants, derivatives traders, and even just finance in general.
Professor Sirbu is a very good teacher. He is bright and excellently prepared for class. His lecures are clear and move at a leisurely but steady pace, covering significant ground over the course of the semester: first order equations, existence and uniqueness theory, general theory of homogeneous and nonhomogenoues higher order equations, systems of linear equations, stability analysis of nonlinear systems, Laplace transform methods for initial value problems, and series solutions. This corresponds to chapters 1 - 7 and 9 from the course textbook "Elementary Differential Equations" by Boyce and DiPrima, which is good but not very advanced. In addition, Professor Sirbu gave a few lectures on interesting or more advanced topics, such as Liapunov functions or Distribution theory, which were not examined. He has a noticable Romanian accent, but his English is excellent and in no way impedes his teaching. The level of rigor is that of an intermediate level course for mathematicians or students of similar mathematical maturity. No knowledge of real analysis, such as is required for the proof of the general existence and uniqueness theorems, is presumed; however, multivariable calculus and linear algebra at both a conceptual and calculatory level are necessary. In addition, the ability to read and write proofs is very beneficial; especially the problem sets tend to contain at least one proof. From an academic and didactic point of view this course more than fulfilled my expectations. It has to be noted that while this is and introductory and not entirely rigorous treatement of Ordinary Differential Equations, this is a course for mathematicians. Although the results and techniques of the course can be applied to a myriad of problems, the course does not focus on applications or spend a lot of time with examples. This is also reflected in Sirbu's teaching style: he tends to cover the general theory before working some simple examples. The homework assignements were fairly easy (ca. 1-2 hours a week) and mainly reinforce concepts from the lecture. Although the grading was fair, the TAs were somtimes careless in their marking and provided no comments whatsoever when points were taken off. The first midterm, although not hard, was definitely too long for the alotted time; the last question was dropped retroactively. The second midterm was a good deal easier. While the TAs grade the straighforward calculatory midterm problems, Professor Sirbu marked the more involved problems himself to ensure fair grading. Before the final, he held a 2 hour long review session, and - at the bidding of a student - made up a full practice final. The final istelf, although cummulative, was neither long nor exceptionally challenging. It contained 1 proof and was marked entirely by the Professor. Regarding overall grading Professor Sirbu is - like another reviewer mentioned - on the generous side of fair. Finally, Sirbu is extremely nice and very approachable. Whether after class, during office hours, or via email, he is always happy to go over or even beyond any part of the material. In general a very good professor. If you get a chance, take a class with him. Do not expect anything spectacular, but very thorough and professional teaching.
The way Mihai teaches ODE is that he treats it not as a topic of its own, but only a tool for other subjects. In other words, he breezes through the material as if it were merely a refresher or a review. It is hard work to keep up with him in class, and to stay awake until the end. I disagree with any reviews that cite his (evident but comprehensible) Romanian accent as the cause for his tedious lectures. As boring as his lectures may be, I would suggest that students attend class anyways. Mihai does well in using intuition to teach -- a sign of his sharpness and thorough understanding of the material. You could rely only on the textbook, but some concepts are better explained by Prof. Sirbu. Don't be afraid to ask him to write more darkly on the chalkboard!!! As far as his grading goes, he is on the generous side of fair, at least on all exams. The class HW average may have been a 7 out of 10, but I'd blame the students' carelessness, not Mihai's harsh grading. I'd take another class with him, if only he would differentiate the cream of the crop from the very good by awarding A+'s...
Sirbu's lectures are hard to follow and, like others say, it's very easy for the students to just zone out completely. That is not his fault entirely ,though, since english is not his native language. Problems sets are hard and are graded rather harshly(average 7 out of 10 for the class). Other than that, Sirbu gives good review problems for the exams and is fairly easy on the grading. Also, I like how he always pass back previous problem sets and exam at the next class. (That is if you bother going to lecture at all to pick them up.) So if you don't have other professors for ODE (yes, don't take Mao Pei), take him and you'll be ok.
The reason this guy does not have a lot of ratings is that he is an average professor. He covers a lot of material (more than average). He grades fairly. The curve is pretty good. His teaching can get a little fast but if you ask him to slow down he will slow down and explain more clearly. He is incredibly helpful at office hours and gives great review problems from the book before exams. I'd say definitely take a class with him but it's not like he is one of those that you MUST take
Professor Sirbu is pretty straightforward about teaching. If you can pay attention during the class, he covers everything pretty well. It's easy to zone out trying to follow him though, especially during a long derivation; I found I had to keep reminding myself of what the point was during proofs and such. He's nice about questions though, and he'll explain things if they don't make sense.