# IIT Madras MS In Computer Science And Engineering Interview Experience

Hello everyone. I recently gave an interview for an MS position in Computer Science and Engineering at IIT Madras. The interview was scheduled to happen on the 20th of July, 2020 within the specified time slot 09:00–13:30. My interview began at 10:30 AM.

*Note*: *Due to the prevailing Covid-19 situation, the written test was canceled and the selection was solely on the performance in the interview.*

**Before the interview**

Out of the 1937 applications received, IIT Madras shortlisted 192 candidates for the interview based on Gate Score and Undergraduate GPA/Percentage. The cutoff for Non-EWS General Candidates was 700 Gate Score and 8.0 GPA / 75% in Undergraduate. The candidates who were shortlisted were emailed a google form in which we had to mention a primary subject to be interviewed apart from Programming subject preferably in the C Programming Language. The primary subject ranged from topics in Computer Science (for eg., Operating Systems, Computer Networks, Computer Organization, and Architecture,etc.) to Linear Algebra, Probability Theory and Signals and Systems. I selected **Linear Algebra** as the primary subject to be interviewed in.

**Interview**

Out of 6 professors present in the panel. 3 of them interviewed me. Let’s call them I1, I2 and I3.

I1 : Tell me something about yourself.

Me : Gave a brief introduction about myself and my work experience.

I1 : OK, so we will start with Programming in C. I will hand over to I2 to start asking the programming question. He also shared a codeshare.io link so that I could write my code there in real-time evaluated by the panel members.

I2 : Hi Aditya, as you have selected Linear Algebra as your primary subject, your programming question is :

*Write a function in C that takes two matrices as input and returns the matrix multiplication of them. Make sure the matrices taken as input are as generic as possible.*

Me : Answered using Malloc for memory allocation and double-pointer approach. Just when I finished writing the functions and was about to write the main function, I1 interrupted…

I2 : I think that is fine. So, we can go ahead with the interview. (calls out I1).

I1 : Alright, so now I3 will be taking over your Linear Algebra interview.

I3 : Hi Aditya, so I see you have written a complex algorithm for Matrix Multiplication in which you have used this dot product formula to evaluate the cells, why not we can use matrix element-wise multiplication as a substitute for Matrix Multiplication and not this complex algorithm?

Me (numbed and thinking what a question he has just asked, wherein schools, you are taught to multiply two matrices with the formula given but never ever stumbled upon this):

I tried to answer the question to the best of my knowledge about Matrix Multiplication as Transformation and Composite of a function but the interviewer was not completely satisfied.

I3 : Okay, I am happy that you could relate it somewhat to Transformation but the answer lies somewhere else. Maybe you could think about it in your free time. The answer lies in the topic Relations, Discrete Mathematics.

Me : Okay, thank you, sir.

I3 : So, are you comfortable with eigenvectors and eigenvalues?

Me : Yes, sir.

I3 : Okay, so does eigenvalue exist for every rectangular matrix?

Me : No sir, it only exists for square matrices.

I3 : Does it exist for all square matrices?

Me : Yes sir, it exists for all square matrices.

I3 (trying to confuse me): Do you want to rethink your answer?

Me : No, sir.

I3 : Think again.

Me : I started explaining that if a matrix is singular, one of the eigenvalues will be zero and if it is non-singular then we can get eigenvalues for the given matrix.

I3 : Okay, got it. Now, do you know what is diagonalization of a matrix?

Me : Yes sir, we can write a given matrix as a product of three matrices. Let A be a given matrix, we can write A = B-1CB

I3 : Okay, I have no more questions. Over to I1

I1 : So, that will be it, Aditya. Our admissions committee will let you know of the results. Thank you for your time.

Me : Thank you, sir.

Overall, the professors were very friendly in there approach and never made me feel afraid of the interview. In all, it was a wonderful experience and the interview lasted for about 25 minutes.

*Resources I used for Preparation*

- MIT 18.01 SC Linear Algebra by Gilbert Strang
- Made Easy Engineering Mathematics Book for solving GATE Questions
- The C Programming Language by Dennis Ritchie, Brian Kerningham for pointer related concepts.

**Verdict**: Selected