In the first round, you meet with an application support engineer who asks you basic questions about your background, why and how much you want to work for mathworks, whether or not you are interviewing with other companies, and some behavioral questions. The interviewer types your answers as you speak. It lasts for about half an hour.
The 2nd round (technical) interview covers: basic math (discrete math, algorithm theory), programming concepts, one programming language (your choice of C, C++, or Java), MATLAB, and your choice of (control theory or signal processing or computer science). It can either be a 2 -3 hours 1 on 1 interview on you college campus OR a 40 minutes phone interview. I had the 40 minutes phone interview. The questions were short answer with minimal "solving" required (because it was over the phone). I would say preparation is very useful (just 2 or 3 days to refresh your memory), and once you do that, the questions asked are mainly easy. It is ok if you don't get all the questions right.
The 3rd and final round is an on site interview. It consists of a technical interview with an application support engineer (similar to the phone interview but since its on a whiteboard, the questions can be a bit more involved), a behavioral interview with an EDG manager, lunch with 2 application support engineers (where you get to ask them about the job and mathworks and they get to assess your fit with the company as well), and salary talk with the senior recruiter.
My impression of application support engineers is that they are young, very nice and welcoming. I didn't feel "judged" or put on the spot in any part of the interview.