In 1969 Sagar received his PhD and I received my bachelor’s degree. This becomes amazing when I tell you that we’re the same age and I never failed a grade, in fact, I skipped grade 3.

I did my Master's in 1970 in Mechanical Engineering at the University of Toronto. I mention in passing, though I guess it's only a coincidence, but maybe not in view of what follows, that my supervisor was an Indian named Ansari. He had been the instructor of the senior undergraduate control course -- the course that first turned me on to control. That the text was Dorf but I liked the course nonetheless is a tribute to Ansari. Sometime during my Master’s program, Sagar, who was then at Concordia University in Montreal, gave a seminar at U of T that I attended. Sagar would have been only 23, but already a professor. The seminar was on the controllability of distributed parameter systems (Sagar had to remind me Sunday evening of this -- I had remembered only the distributed parameter part). That was my subject too at the time. I was modeling and controlling a heat exchange system in the lab, with flowing water, pipes, heaters, and pneumatic valves with PID control. Sagar's seminar was of course mathematical. His infinite-dimensional system didn't even have a pde! I was stunned by the thought that my heat exchange system could be modelled merely by a non-rational transfer function. Although I didn't understand much during the seminar, I was very impressed by its elegance. Abstraction was new to me, coming from mechanical engineering. So I wrote and asked Sagar if I could be his PhD student at Concordia. I had a scholarship, so I didn't need financial support. Sagar agreed.

I arrived at Concordia to find the EE department was a little India. The chair of the department was Indian, a man named MNS Swamy. So were many other professors, including the vice-chair. There were about 25 grad students in EE -- I was the only one not an Indian. Everyone welcomed me warmly into their group. I was aware of the fact that I was the only native Canadian among this group of grad students. We would go out to dinner and someone would ask me, for example, who was my favourite author. Although I was keen on Kafka, Dostoevsky, and other dark writers, I found myself oddly standing up for my English heritage -- I said, Dickens. In this environment, Sagar also warmly welcomed me. I think I was a bit of a prize student, being a scholarship holder from U of T. He asked me to call him "Sagar," and it was only partly because I couldn't very well manage "Professor Vidyasagar." Two years later he also taught me to pronounce "Shakunthala," and that took several lessons. For my PhD topic Sagar suggested I work on the robust decoupling problem, but I got nowhere. I stayed at Concordia for only a year, for personal reasons.

I moved back to U of T in 1972 and did my PhD with Murray Wonham. Sagar and Shakunthala married in the same year.

Sagar and I kept in touch and in 1977 I started a postdoc at Cambridge. I lived in a room in a house, a room on the first floor that looked out on the River Cam, a room that was damp and chilly. One Sunday Sagar was to visit me. Somehow in the afternoon I was in my room napping, wearing earplugs; Sagar arrived at the house; my landlady, Mrs Sargent, knocked on my door -- no answer; she knew I must be there; she showed Sagar into my room; I looked like a cadaver lying on the bed, I'm sure; Sagar stirred me; I woke: "Sagar! You're here!" I was so flustered. Sagar suggested we go outside for a walk on the common where it was warmer. We chatted about this and that and the topic came up of robust regulator theory for input-output models, something I was trying to work out. I had done the same problem for my PhD but for state models. How the internal model could be induced by the requirement of robustness. But in an input-output framework how could you characterize uncertainty for unstable systems? Sagar had the perfect, natural way: via the graph, or in modern terms, the behaviour. We worked out Sagar’s idea in a paper together.

After Cambridge I had the amazing good fortune to be offered a one-year postdoc position in Montreal, half at Concordia with Sagar and half at McGill with George Zames. Sagar was so gracious, understanding, and humble, that he suggested or at least went along with the arrangement that my office be at McGill, Concordia being 20 minutes walk away. Consequently, Sagar received very little from me in return for his generosity in paying me. We did, however, have many pleasant times at La Crêpe Bretonne, having crepes with maple syrup. During this time Sagar and Shakunthala had a cottage in Vermont. Once they invited me along on a trip to the cottage. In this rustic setting Sagar sang a Simon and Garfunkel song:

I wish I could say this revealed some personality trait about Sagar, but I can't, because I assume everyone would rather be a hammer than a nail. At the time it did surprise me that he knew Simon and Garfunkel songs, but I came to realize there’s very little he doesn’t know. In hindsight I think he was trying to connect to me through music that I would be into.

Sagar and Shakuntala moved to Waterloo in 1980, One year later I became Sagar's junior colleague at Waterloo. Junior? Yes, he's all of 9 days older than I am. In Waterloo the dessert place of choice for Sagar was the Mozart Cafe. At Waterloo Sagar invited Allen Tannenbaum to visit. Allen and I connected immediately ... but that’s another story.

So after 38 years here are some things I know about Sagar:

Finally, I feel like I’ve been his student for 38 years, because every time I meet him I learn something new.