Rohit’s Ramblings

Archive for the ‘Technology’ Category

Buffer overflows - they are vulnerabilities sublime,
They’re easily overlooked most the time,
But when you go through sloppy code with a fine tooth comb,
With such ease you will uncover many a ticking time bomb,
And then it will dawn upon you… why “duffer” and “buffer” rhyme.

Hi Friends!

As promised, I am placing the slides & notebooks for the Mathematica session here. I have also composed a couple of limericks to go with it :).

It was an attempt to make Mathematics seem more groovy,
And also to make the students Mathematica savvy,
But when the concepts got too deep,
And a couple of students fell asleep,
I thought I shouldn’t have made it so heavy.

I feel that its important to see beyond your scope,
Even if initially it seems difficult to cope,
I admit the content was a little bit dense,
And needed much effort to make sense.
But without raising your engine, you can never climb the slope.

That being said, I would still appreciate any feedback you may have to contribute. Please leave a comment below.

Click here to download the slides & notebooks.

Found this neat comic called “Regular Expressions” on xkcd -

I swear! I always thought that someday in the future, my knowledge of … - - - … (morse code for SOS) would help me…

Although the Indian learning system places emphasis on memorizing multiplication tables (my grandfather supposedly knew multiplication tables till 40×12 by heart) – kids should also be given a contingency plan to fall back on – in case their memory fails them.

This method helps to quickly calculate the product of two numbers, each of which is between 6 and 10 using only your hands and knowledge of smaller products such as 2×3.

1. First we have to number the fingers on our hands as follows –
   
2. Now let’s take an example – say 8 x 7 = 56. Make the “8” finger on one hand touch the “7” finger on the other hand
   
3. Digits in the tens place - Count the fingers below (and including) the “7” and “8” fingers. In this case there are total 5 fingers.
   
4. Digits in the units place – Multiply the fingers above the “7” and “8” fingers. In this case 3×2 = 6.
   

There you have it – 7 x 8 = 56!

Have you seen one of these floating around on the internet?

An example of a Captcha found on the internet.

These are called CAPTCHAs. Wikipedia describes them as “a type of challenge-response test used in computing to ensure that the response is not generated by a computer”. In simple words, the web servers that serve the above image wish to ensure that it’s a human being at the other end (and not an automated script or bot of some sort). Hence, if the response is correct – the entity that created the response must be human.

Now, there are several ongoing efforts to try and digitize mankind’s physical texts into a publicly accessible digital archive. These efforts rely on OCR software to convert the scans of physical texts into digital content. However, OCR isn’t perfect. It often makes mistakes in recognizing words. But, it is kind enough to point you to the words where it feels it may have gone wrong.

Question is – Is it possible to harness the intelligence of the masses surfing the internet to aid the digitization process?
Answer is: Yes, with the assistance of reCAPTCHA.

reCAPTCHA technique is simple – it serves two words for the CAPTCHA: One of the words served has been flagged as “not recognizable” by the OCR during conversation. The other one is known (i.e. it has been successfully recognized during OCR). Now, the human user attempts to decipher both words. If the user enters the recognized word correctly – he has most likely entered the unrecognizable word correctly as well. This can be confirmed by serving the unrecognizable word to several users – thereby improving the confidence. Ultimately – the actual contents of the unrecognizable word are registered. That’s one more correct word added to the digital archive.

Smart!

Read more about reCAPTCHA here.