Tuesday, July 24, 2012

So you have started hating Khan Academy

he he he

So people have started calling Salman Khan a bad teacher. In contrast it is his this gifted ability to explain things which made him popular. Without any doubt he is a very good teacher. If he was not we wouldn't have been discussing him.

But he has also publicly criticized the teachers who teach for the sake of working. You know people get in that comfort zone, regular salary streaming in. Who cares about teaching after that! The initial enthusiasm drowns and laziness and muscle memory sets in. Khan has hit them on the right spot. They have woken up. But instead of correcting themselves they are lobbying around the media houses and howling.

And there is another group of people who want to sell themselves riding the hype around all this. They are great trained teachers who have worked for years to create those error-free contents. They appear in front of their students with that additional halo around them and start their lectures. But students don't connect with soul-less and robotic teachers! It is true and all of us have experienced it sitting through those factories called schools. Confess it!

he he he

Saturday, July 21, 2012

minimum deviations

Median leads to minimum sum of absolute deviations.
Mean leads to minimum sum of deviation squares.

Thursday, July 19, 2012


Zero is a wonderful concept we humans created to simplify our understanding of everything, it helps to build a world starting from anywhere(or nowhere ;)). Place that zero on your dining table and start imagining that bowl whose center of base coincides with the zero. That 3 dimensional world starts appearing spontaneously around that zero. In contrast imagine searching for that absolute zero in this never ending world before starting to build that bowl around it! Due to zero it has become so damn flexible to express ideas portably and modularly! Zero is everywhere and without it we wouldn't have come this far in expressing our ideas. So long with this relativistic and referential understanding of zero.

Does zero exist only in referential domain? Is there an absolute zero somewhere where it all started in absolute form? If it really exists then everything is connected and related to each other with respect to that absolute zero! Time to return to the surface and breath normally. :)

Tuesday, July 03, 2012

Mean calculation based on previous mean value

mean_n(a) = ( 1/n ) * ( (n-1) * mean_n_1 + a )

where mean_n is mean of all numbers till a.
           mean_n_1 is mean of all numbers except a.

Now if the n is big then it can be approximated to: mean_n_1 + a/n.

The interesting part is (a/n). If a wants to participate in the mean calculation then it just needs to be divided into n portions and added to the previous mean(for n-1).

Online learning vs Batch learning

Any machine learning application should eventually be really open to online learning strategy. Once they have learnt enough with offline batch learning strategies and ready to be used, then they should be reconfigured to switch to online approach.

Money in and out

If you earn money easily(you know what I mean), then there is a high chance that you will spend it freely. Hard earned money won't be spent that easily.  This feedback mechanism looks so sensitive that things could go out of hand very easily at a macro level. Market is such a delicate work of balance!