## Climate Change is for REAL!!! :(

It’s obvious to anyone who has been in Kerala for the last few days. It’s been unbelievably HOT… Everyone’s finding it hard to cope with. And it’s only the end of February! You hardly feel like doing anything when it’s so hot. The heat saps all your strength.

The climate situation is frightening, to say the least. It is changing right in front of your eyes. I have been keeping a keen eye on the climate for the last few years. I remember, not too many years ago, when I was in fifth or sixth, it would be raining on the 1st of June no matter what, when the school reopened after the summer holidays. But what has happened in the last few years? In 2006, there was heavy rain in the last week of May, and then a very dry June and the monsoon resumed only in July. And then we had extraordinarily heavy rainfall in Monsoon 2007 but again, which started very late. In April 2008 we had over two weeks of downpour which destroyed most of the crops. And this year, again a bizarre monsoon, and very little rainfall.

It seems obvious where we are heading. It’s frightening. The Earth’s atmosphere, and the whole biosphere is an extremely complex system and has a delicate equilibrium. When that’s disturbed, the natural forces act to try to bring it back to equilibrium. What do you say to people who argue that Climate Change is a hoax?

## Nothing Short of a Miracle!

That’s what happened today. The occasion was a cultural night arranged by the Staff Club of NITC (no one knew one even existed, till today!). Some of the faculty got together and wrote a drama to be staged tonight. I learnt about it from Deepak sir’s blog a few days ago, and that in itself seemed like a miracle. But the actual performance was nothing short of unbelievable, to say the least! It was fantastic. About the drama itself, I keep that for another day. I’m just too dazed by that performance to analyze it critically. Besides, Deepak sir has promised to make the script and video available.

I always knew that the faculty members were fantastic people outside the classroom, but hats off to them for this wonderful performance!

## Ishmael

Ishmael thought for a moment. “Among the people of your culture, which want to destroy the world?”

“Which want to destroy it? As far as I know, no one specifically wants to destroy the world.”

“And yet you do destroy it, each of you. Each of you contributes daily to the destruction of the world.”

“Yes, that’s so.”

“Why don’t you stop?”

I shrugged. “Frankly, we don’t know how.”

“You’re captives of a civilizational system that more or less compels you to go on destroying the world in order to live.”

“Yes, that’s the way it seems.”

“So. You are captives- and you have made a captive of the world itself. That’s what’s at stake, isn’t it?- your captivity and the captivity of the world.”

“Yes, that’s so. I’ve just never thought of it that way.”

I hope most us wouldn’t deny that we are destroying the world. If you do, please look around you and think again. But why? Why can’t we stop? Is it that we are fundamentally flawed? That’s what people generally seem to believe. All the time we hear that this is the price we have to pay for civilization, the price for being human, the price for all the advancement we have had so far.

The truth is that our civilization is shockingly ignorant of the laws that govern life on our planet. No, not ignorant, really. Shockingly convinced that those laws do not apply to us. Like Mr.Quinn says in his wonderful book, imagine a person who jumps from the top of a tall building and says- “See, the law of gravity doesn’t apply to me. I’m still in flight!” Surprisingly unscientific for such a scientific people as us, wouldn’t you say?!

If you have ever felt the thought of why we seem unable to curb our ever-accelerating fall towards destruction, haunting you, this book is a must-read. It’s a thought that has grown on my mind during the last few years, and has come to occupy a central position in my mind and changed the way I look at the world. That must be why the ideas expressed in Ishmael resonated with my thoughts.

Ishmael is a book full of original ideas and should be right up there among the best books that have ever been written.

## DSP Lab – Week 1

### Constructing the Complex Plane

Suppose we have a sampled signal defined by the sequence $h(n)$, $n=0,1,2,...,N-1$

Its Z- transform is given by $H(z) = \sum_{n=0}^{N-1} h(n)z^{-n}$ .

It maps the original sequence into a new domain, which is the complex plane $z=e^{sT}$ where $s=\sigma+j\omega$ is the parameter in the Laplace domain and $T$ is the sampling period.

The $j\omega$ axis in the $s$-plane maps onto the unit circle with centre at the origin in the $z$-plane. So the value of $H(z)$ at different points on the unit circle actually gives the contribution of the frequency component given by $\angle z$, in the original signal.

This, in effect, gives the Discrete Fourier Transform of the sequence. Consider the following example:

%original sequence
h = [1,2,3,4];

%number of chosen points on the unit circle
N = 64;

%define the chosen points
z = complex(cos(2*pi/N*(0:N-1)),sin(2*pi/N*(0:N-1)));

%evaluate H(z) at each point
for i = 1:N
H(i) = 1+2*z(i)^-1+3*z(i)^-2+4*z(i)^-3;
end

%plot the unit circle
plot(z)

%plot the value of H(z) along the unit circle
figure
plot(abs(H))

%plot the N-point DFT of h(n)
figure
plot(abs(fft(h,64)))


This example computes the value of $H(z)$ at 64 uniformly spaced points on the unit circle and compares it with the 64 point DFT. We can see that both (fig. b & c) are identical.

unit circle

value of H(z)

abs(fft(h))

## Digital Signal Processing Lab

We are very lucky to have Abhilash sir in charge of DSP lab this semester. I really used to enjoy his classes during the Signals and Systems course in the third semester. In fact it’s the only course so far, in which I’ve felt like paying attention. I think I will document whatever we do in the lab, on my blog, when I get time.

## Learning from the Master

I’ve got Information Theory and Coding as one of the theory courses this semester. Just out of curiosity, I downloaded Claude Shannon‘s famous 1948 paper, A Mathematical Theory of Communication, which is the foundation of Information Theory. To my pleasant surprise, I found it quite readable. In fact, I ended up using it as a supplement to the text! It’s such a great paper. No irrelevant algebra or proofs. And I find it exciting to learn directly from the words of the person who founded the subject!

I dive down into the depth of the ocean of forms,
hoping to gain the perfect pearl of the formless.

No more sailing from harbor to harbor with this my weather-beaten boat.
The days are long past when my sport was to be tossed on waves.

And now I am eager to die into the deathless.

Into the audience hall by the fathomless abyss where swells up the music of toneless strings
I shall take this harp of my life. I shall tune it to the notes of forever,
and when it has sobbed out its last utterance,
lay down my silent harp at the feet of the silent.

–from Gitanjali, by  Rabindranath Tagore