blinkdagger

This is the sixth post recounting my interview experience with The MathWorks. Today’s post focuses on the on site interview. If you only read one post in this series, it should be this one! Click here to see a list of related posts.

The Technical Interview: Brief Overview

The technical interview on-site is simply an extension of what the phone interview was like. The technical interview consists of three things: you, the interviewer, and the whiteboard (in some cases, you’ll be asked to do some stuff on the PC as well!). Initially, I was a little bit nervous because I thought the technical interview might be in front of a panel grilling me on the nuances of MATLAB. Instead, the interview consisted of only me and a rather young MathWorks employee. That in itself immediately put me at ease.

The questions asked during the on-site interview are a little more in depth than the questions asked during the phone interview. Luckily, these questions don’t require elaborate analysis. Just imagine that the on-site questions are 1 degree of difficulty higher than questions on the phone interview. Since you will have a white board to work with, the type of questions the interviewer can ask span a much greater space than the questions on the phone interview.

In the technical interview, you’ll need to be able to think on your feet. You won’t have too much time to sit and ponder. You’ll have to explain your thought process while you’re working through problems. On the flip side, you’ll also get some helpful tips from your interviewer if you get stuck on a particular problem. If you have no idea on how to approach a problem or initially struggle, they’ll try to nudge you in the right direction. But if you still have no idea what is going on, that doesn’t bode well for you. Remember that if you don’t do well enough on the technical interview, they will immediately send you home. Try not to let this happen to you!

The technical portion of the interview lasted for about 3 hours for me. I hear that on average it goes for 2 hours. My interviewer actually told me that we hadn’t even gone through all of the questions yet when the 3 hours were over!

Getting to the Good Stuff

I guess I had a case of the jitters, because the first question I was asked froze me. The question in itself was pretty easy, but for one reason or another, I couldn’t for the life of me remember what to do. Maybe it was the frazzled nerves or lack of sleep. I think my brain wasn’t warmed up yet, so I struggled quite a bit. After that little hiccup, things got easier, or I got smarter. The rest of the interview went somewhat smoothly.

Sample questions that will prepare you for the interview. These questions do not necessarily reflect what you will see at the actual interview.

MATLAB

1. Write a function that takes in as input an integer and then outputs the sum of all of its digits.
2. Given a particular vector: X= [4 10 4 50 100 23], how do you remove the 4th element?
3. Given the same vector, how do you add 49 in between 100 and 23?
4. Give some examples of Objects within MATLAB.
5. Given two vectors, x and y, how would you plot this data? How would you change the limits of the axes? How would you reposition the figure? How would you obtain a list of all the properties of that figure? How would you change a property of that figure from the MATLAB command prompt? For example, how would you change the background color of a figure?
6. What is preallocation and why is it used?
7. How would you create a 10×10 matrix with values ranging from 1 to 77?
8. Write a function that takes in as input a matrix and outputs a single number. The function is to sum up the even columns within the input matrix.
9. Is vectorized code always better? Explain the advantages and disadvantages of vectorization.
10. Discuss how you would go about debugging your code in MATLAB.
11. What happens if you try to assign a value to a variable that has a predetermined value (i.e. pi, eps)?
12. I recommend going through the entire contents of “getting started” in the MATLAB help. You’ll be surprised at how much you can learn from there!! I just got done looking through it myself. I knew maybe 85% of the things in there, but learned quite a bit which helped reinforce my MATLAB knowledge.
13. Also, it might help if you spend some time looking through the tutorials we offer here as it could come in handy.

Mathematics

1. The Monday Math Madness series offer some cool problems that will test your problem solving skills. I recommend looking at these to get your math mojo rolling. MacBook Madness and Blinkdagger burgers are two good ones.
2. Plot the following function: [tex]y(x)=sin(x + pi)[/tex]
3. Find the area under the curve of the function above from 0 to pi.
4. Find the volume of the object that is created if the above function is rotated around the x-axis.
5. What is the derivative of [tex]y(x)=[x^3 +2x]^2[/tex]. What is the anti derivative?
6. Clearly explain what a derivative and integral are (pretend you are explaining it to someone who is intelligent, but not well versed in mathematics). Provide examples.
7. Given a polynomial , [tex]y(x)=[x^2 + 5x + 4][/tex], how would you find the roots?
8. When is the “completing the square” technique useful?
9. What is a gradient? How do i find the gradient of the function [tex]f(y,x,z) = 5xy + 6xz^2 + z[/tex]. Give a situation wherein you might use the gradient.
10. The basics of vector calculus is also something you should focus on (they should have told you this before the interview).
11. Dot products and Cross products. Given two vectors that each contain three elements, how do I find the dot product and cross product? Explain what a dot product and cross product are. What are they used for?
12. Elementary Linear Algebra: reduced row echelon form, inverse of matrices, eigenvalues and eigenvectors, transposes, order of operations, vector spaces

Computer Science

1. They will ask about classes, constructors, destructors, variable types, linked lists, pointers, hierarchies, parents, protected, private, and public variables. To be honest, I again bombed the CS portion although I tried studying for it. But they understand that if you aren’t a computer science major that some of the questions they ask are going to be pretty tough
2. If you aren’t a CS major I would imagine it would be difficult to answer some of the questions they throw at you. I recommend you study the basics and pray for the best.
3. I would recommend going back here to look at what we said in the last post about computer programming concepts as there isn’t really much more to be said. I felt like some of those questions I would never be able to answer in a million years.

Control Systems

1. For the following system, [tex] G(s)= frac{(s-1)}{(s+2)(s+5)}[/tex]:

   what are the poles and zeros? Is the system stable? Plot the root locus of the system. What information can you extract from a root locus plot? Plot the transient response of the system. Put the system into state-space form. What is the natural frequency of the system? What is the damping of the system?

2. Be familiar with both analog and digital systems.
3. What is a PID system? Describe each of the components.
4. How do you determine if a system is controllable or observable? What does it mean if a system controllable? Observable? Stable? Non stable? Marginally stable? What are the conditions?
5. Be able to perform block diagram algebra.
6. How do you find the closed loop transfer function of a given system?
7. What happens to the system when the natural frequency is decreased? What happens if it increases?
8. What happens when damping is decreased? Increased?
9. Given an unstable system, what are some ways to make it stable?
10. Given a transient response, identify the following: settling time, rise time, steady state value, etc?
11. Bucknell’s site has some very good information that will help you study

The Behavioral Interview

The second half of the interview was a lot easier in my opinion. I sat down with Andrew Tseng and we basically just had a conversation. He would ask me some questions and I just tried to truthfully answer them to the best of my ability. Be sure not to embellish or exaggerate too much, as they WILL check your references! It’s still a good idea to go over some of the behaviorial questions as they help you formulate answers and help you think on the fly. Here is a good site that has a bunch of sample questions. I would suggest practicing these questions aloud as to simulate the real deal. One of the things that I remember vividly was that Andrew mentioned multiple times that “The MathWorks only hires the best of the best.” So if you get this far, you should feel proud of yourself!!

After speaking to Andrew, I also sat down with Martha Burns, the corporate recruiter, for a small talk. We chatted about some things here and there, so it really didn’t feel like an interview at all. The second half overall was much more pleasant than the first. After all was said and done, The MathWorks tried to call a cab for me so I could get to the train station in time to catch the 4:00pm train back to Boston. But since the cab was too far away to get me to the train station in time, Martha Burns volunteered to take me instead. Talk about going the extra mile! Thanks again Martha!

Dan’s Thoughts

Quan has compiled a great list of sample questions. Make sure you review our tips in technical phone interview to help you prep the on-site interview. The session is definitely longer (took me about a little over 2 hours) and more in-depth. I probably could have done a lot better if I took it fresh out of college. Answer questions to the best of your ability, and don’t get discouraged if you miss one here and there. Also, I noticed the examiner took notes while I was answering the questions. On one of the questions that I was asked earlier in the interview, I realized I had messed up, and I corrected my answer. The interviewer then had to erase some of the stuff he wrote.

With that being said, I think the on-site technical interview is a formality. As long as you don’t bomb it completely you will proceed to the managerial interviews. In general, I found that following the STAR method works pretty well (click on the link if you’ve never heard of it before, it’s quite handy). Here are 5 quick questions that you should be prepared to answer:

1. Q: How is your day so far? Tell me about yourself. Remember to greet your interviewer and to be courteous. Start out with energy and be excited. Even if you are tired, don’t mention that you are! When asked “Tell me about yourself,” try to connect it back to The MathWorks or the interview. They are not interested in where you are born unless it is somehow related to the interview. This question is designed to see how you set the tone/focus of the interview.

   Lesson learned Start out Strong

2. Q: What did you learn in College? Why Mathworks? When you respond to the interviewer, structure your response in an easy way to follow. You can say “There are three things I have learned in college. First…”, “I think my interest in Mathworks can be divided in two parts: Challenging Environment and Personal Development. I will start with Challenging Environment…” Provide them with an outline and don’t ramble. If they can’t follow your responses, it will reflect badly on your verbal/organization skills. However, don’t memorize potential responses as it will make you come off too rigid, boring, and not unique.

   Lesson learned Structured but not Rigid.

3. Q: Tell me an instance where you were in a conflict. How you approached the situation and if you resolved it. The strategy here is to have prepared situations that can be applied to all types of questions. Think about three important events, projects, or challenges you faced in your education/career. Refresh yourself by experiencing those moments in your mind. Write down as many examples that exhibit: conflict resolution, leadership and management, teamwork, coping with failure, analytical thinking, and how to approach a problem. Sometimes you can substitute that list with the company’s vision/goals. Now you will be ready to answer all questions that require you to recall an instance.

   Lesson learned One Size Fits All Examples.

4. Q: “Why…”, “I see on your resume that…”, “That is interesting, but have you thought of…” Sometimes interviewers will drop clues and try to guide the interview to somewhere specific. Do pick up on these hints and answer specifically to his/her questions. If the interviewer is helping you/making a suggestion, don’t be stubborn and incorporate it. Also, if your response is getting long and you notice the interviewer is losing concentration, wrap up your response with some key points. Being perceptive and observing your interviewer will help you formulate your responses. If you can read minds that would be great too.

   Lesson learned Pay Attention to Details.

5. Q: What would you do? How would you describe yourself? There is no need to be someone else when you have made it so far by simply being yourself. Being who you are helps you be at ease, appear natural, and remain candid. They will check all your references to ensure your statements are consistent!

   Lesson learned Be Yourself.

Next Time

Next time, we’ll talk about our experience at The MathWorks outside of the technical interview and share our thoughts and feelings. In addition, we’ll touch on the offers that we received and how it all played out.

Quan and Dan are just two normal guys who happen to know a thing or two about MATLAB. Together, they team up to bring you the latest MATLAB offerings. They are a tandem just like peanut butter and jelly. Stockton and Malone. Jordan and Pippen. Samwise and Frodo.