Dear sir,

Dear sir,

Imagine yourself in a very cold place. You look here and there and see plenty of wood logs to build up a fire. And fortunately, you happen to have a lighter to make fire. You bring some woods, pile them up in a pattern to have sufficient space for air and then light them up.

Voila, you made a fire and now you can sit comfortably around it. But, then you wanted to have more temperature for more comfort in that cold place. What do you do then?

So, you stand up, bring some more logs of wood and place them on that burning pile.

I know, sir, that you are a good observer. You stay silent most of the times and find solace in observing things. I know you have an excellent analytical ability. Your lecture classes, your concised speeches, your way of tackling a complex control system problem just speak a volume about it.

And hence I know that you can observe what happens when you place more logs atop the burning pile. You will observe the reduction of the temperature. How comic is life and its events. Just when you thought that you will have more comfort by burning more logs of wood, you see the complete opposite of that right in front of your eyes.

And I know, you are smiling right now because you do know what is the explanation behind it. You do know that at the end, the game is all about non minimum phase system. Being a mathematician that you are, a transfer function comes up in your mind.

But what is trnasfer function? It is, in layman terms (for I am a layman) the ratio of output to input considering the initial conditions as zero. And your mind already has an image of that transfer function.

G(s)= (1-sT)/ (1+sT) and you do know the obvious depiction of that transfer function in s-plane.

So, here is a mathematical model for a system which resembles that burning pile of wood. And you know the response that you would get for an input to that system.

Immediately you think of a plot of response with respect to the passage of time. And in all the probabilities, it would resemble the plot where the response dips below the positivity and goes straight towards negativity and rises ahead, sharply, towards positivity after a span of time.

Don't bother about that guy looking puzzled at the plot. That's just my curious mind trying to grasp any meaning it can provide.

And hence you come to know why there is a reduction in temperature for some time when you placed additional logs.

But you know that already. It was I who didn't know how the nature of life is so similar to this non minimum phase system.

When one tries to do something worthful, he has to face such downfalls and I have faced one as you might have guessed by now. But I will rise against the tides. And then will laugh at the downfalls for daring to make my life miserable.

This post is dedicated to you, for I have always been an admirer of your teachings and have always considered you my idol. 

You might have forgotten that fateful day, in the morning hours when there were countless students raging protest against the obvious injustice done to a dead body. You might have forgotten my face, but it was that face which tried to shield you against the mob, for the mob knows no wisdom. It was I who suggested you to go behind the shop and run away and it was I who heard what you had said at that moment "I will never run away"

It was always a dream to have a frank conversation with you, but your silence made my steps towards you impossible. But we did meet face to face with each other and I failed miserably at impressing you. But I learnt two or three things from that meeting and hence of all the people that I know of, you have been given a special place in my cherished space, this blog, for from the bottom of my heart, you will always remain my hero.

Your fan
Pranju Chakrapani


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