I had applied for both CDS and CSA M. Tech. Research and got called for both. As I could not clear written exams of IITH, IITG, and programming test at IITB, I wasn’t sure about IISc too.

Interviews were conducted over a period of 5 days from 20th May to 24th May. My interview dates were

21st May: CDS (afternoon session)

22nd May: CSA (morning session)

I reached the campus in the morning at 5:30 am. I had to wait up to 1 pm. Till then I roamed the campus 😊

Test started at around 1:30 pm. I shook my head on seeing all the 5 questions. I was able to attempt just 2 with confidence. I had doubts for the 3rd one and other 2 I knew that I did wrong. In all, I totally messed up with the test and as a result, I was shown the exit door.

Depressed after the CDS test I went to Yeshwantpur to get a room. One of my friends was coming to stay with me. He had his interviews on the next 2 days. Did some rest and then revised my notes to be prepared for the next day.

CSA had 3 choices of stream – Theory, Systems, and Intelligent Systems. Each stream had some background subjects. I had prepared for Intelligent Systems, which had Linear Algebra and Probability Theory as background subjects.

The test was scheduled at 9 am. Reached the campus by 7:30 am. Did breakfast at Prakruthi. Entered the exam hall at around 8:20. We had to select a pool before the test. Each pool had particularly designed tests. Test started at 9 am. It contained 10 questions based on probability and linear algebra. All questions were simple. I had doubts about two questions. Results were announced within 20 mins. Two groups of 7 each were selected from 17-18 candidates for intelligent system pool. I was called at 4^{th} in group one. I don’t know why called in two separate groups.

The interview started at around 10 am. I got called at around 11:30 am. Went inside. Initially nervous a bit. The panel consisted of 3 professors.

Prof 1: Told me to sit down, while he went to erase the whiteboard.

Me: Thank you sir

Prof 2: Why did you give the highest preference to Astronomy and Astrophysics? It’s really interesting!

(meanwhile, prof 1 joining in the conversation)

Me: (In a complete surprise!) What sir? I didn’t. It must be a mistake.

(Both professors laughed and the atmosphere got lighten.)

Prof 2: Okay, so you did your BTech from Panjab Unversity.

Me: Yes sir.

Prof 2: What’s your cgpa?

Me: 7.13 sir.

Prof 2: You gave Gate 3 times (saying this he read out each of my scores), 432, 473, 692. It’s a quadratic function!

Me: Yes sir (In my mind – nice observation!)

(All this took nearly 4-5 mins)

Prof 2: So Ravi shall we start with Linear Algebra?

Me: Sure sir.

Prof 1: (Signaled me to go to the board) Take a matrix A of size m $\times$ n. What will be the size of $A^{T}$

Me: Told him.

Prof 1: What will be the size of $A^{T}A$?

Me: Told.

Prof 1: Will it be a symmetric matrix?

Me: Yes sir

Prof 1: How? Can you prove it?

Me: (I knew this but at that moment I couldn’t recall) Sorry sir I’m not getting there.

Prof 1: (He sensed the difficulty and asked) What’s the property of a symmetric matrix?

Me: This question was enough to remind me of everything. Did the proof.

Prof 1: If A is a real matrix then eigenvalues of $A^{T}A$ will be real or imaginary?

Me: Real

Prof 1: Take $AA^{T}$ and specify its size.

Me: Wrote on board.

Prof 1: If m > n then will the eigenvalues of $AA^{T}$ be a subset of eigenvalues of $A^{T}A$?

Me: (Didn’t know anything about it, Tried something but couldn’t progress.) Sorry sir, I don’t know this.

Prof 2: What is a random variable?

Me: Explained.

Prof 2: Suppose a coin is tossed. How will you use random variable?

Me: (After thinking for a while) Let X be a random variable that takes value head or tail (wrong)

Prof 2: What type of values a random variable can take?

Me: Numerical. (Oh! then I corrected my previous answer) Let X denote no. of heads i.e. either X = 0 or 1

Prof 2: What distribution does it follow?

Me: Bernoulli distribution

Prof 2: If the probability of Head is ‘p’ then what are the probabilities of X=0 and X=1?

Me: Answered.

Prof 2: Now if the coin is tossed twice then what values can X take?

Me: (Struggled a bit but finally got it) 3 values 0, 1, and 2

Prof 2: Write probabilities for each of the values of the random variable.

Me: Wrote.

Prof 2: What distribution does it follow?

Me: N number of bernoulli trials is binomial distribution. Here N = 2.

Prof 2: Okay, you can go now

Me: Ok sir, thank you!

Total time of the interview was around 15-20 mins. I could not answer one question. I had made my mind that here also I may not get selected. But still, I hoped for positive response.

5^{th} June was the happiest day of my life – got the offer letter

Rank – 888

Score – 692

Thank you for your patience! I hope it is helpful for future aspirants

You reached the campus at 5:30 a.m.That's good :)