The Agony and the Ecstasy

That night, as he lay sleepless in bed, he thought. "Life has bee good. God did not create me to abandon me. I have loved marble, yes and paint too. I have loved architecture, and poetry too. I have loved my family and my friends. I have loved God the forms of the earth and the heavens, and people too. I have loved life to the full, and now I love death as its natural termination. Il Magnifico would be happy: for me, the forces of destruction never overcame creativity"

From The Agony and the Ecstasy

Funny Trick using your gmail id

Whenever some website recognizes the uniqueness of account using your email id, you can by pass that check while using your gmail.com id, because gmail.com does not consider symantics of '.' within the username of its account.

So, if you are yourname at gmail.com, it is same as your.name,  y.ourname or any other thing for the same account. But for the other website, most often they tend to look it as different ids.

I tried this with http://en.gravatar.com/, when it said that my id is already set (I had not/ dont remember how), so I simply used or.senthil. While testing forms, you can use this trick too.

Bogosort

"In computer science, bogosort (also random sort, shotgun sort or monkey sort) is a particularly ineffective sorting algorithm. Its only use is for educational purposes, to contrast it with other more realistic algorithms. If bogosort were used to sort a deck of cards, it would consist of checking if the deck were in order, and if it were not, one would throw the deck into the air, pick up the cards up at random, and repeat the process until the deck is sorted."

http://en.wikipedia.org/wiki/Bogosort

Ariane 5 Flight 501

While listening to an introductory programming class, came across the mention of this this "Ariane 5 Flight 501" failure incident, which was caused by Arithmetic Exception and Integer overflow resulted from automatic type casting float to integer in the ADA program. Very costly software bug.

This German article discusses the issue. Below is the English translation of the same with the help of translate.google.com with some comments.


Ariane 5 - 501 (1-3) Ariane 5 - 501 (1-3)

4th June 1996, Kourou / FRZ. Guyana, ESA Guyana, ESA

Maiden flight of the new European launcher (weight: 740 tons, payload 7-18 t) with 4 Cluster satellites

Development costs in 10 years: DM 11 800 million I am not sure about 11 space 800 million. If it is, then its 4 trillion Rupees roughly.

Ada program of the inertial navigation system (excerpt):

 ... 

 declare 

   vertical_veloc_sensor: float; 

   horizontal_veloc_sensor: float; 

   vertical_veloc_bias: integer; 

   horizontal_veloc_bias: integer; 

   ... 

 begin 

   declare 

     pragma suppress(numeric_error, horizontal_veloc_bias);

   begin 

     sensor_get (vertical_veloc_sensor); 

     sensor_get (horizontal_veloc_sensor); 

     vertical_veloc_bias := integer(vertical_veloc_sensor); 

     horizontal_veloc_bias := integer(horizontal_veloc_sensor); 

     ... 

   exception exceptionnelle 

     When numeric_error => calculate_vertical_veloc (); 

     when others => use_irs1 (); 

   end; 

  irs2 end;



Effect:

37 seconds after ignition of the rocket (30 seconds after Liftoff) Ariane 5 reached 3700 m in altitude with a horizontal velocity of 32768.0 (internal units).This value was about five times higher than that of Ariane 4th

The transformation into a whole number led to an overflow, but was not caught.

The replacement computer (redundancy!) Had the same problem 72 msec before and immediately switched from that.

This resulted in that diagnostic data to the main computer were sent to this interpreted as trajectory data.Consequently, nonsensical control commands to the side, pivoting solid engines, and later to the main engine, to the deviate Flight no large (over 20 degrees) to correct them.

The rocket, however, threatened damage control and tested all himself (39 sec). I guess auto-destruct.

An intensive test of the navigation and main computer had not been undertaken since the software was in tested Ariane 4.

Damage:

DM 250 million start-up costs (~ 8.5 billion INR)

DM 850 million Cluster satellites (~ 29 billion INR)

DM 600 million for future improvements (~ 20 billion INR)

Loss of earnings for 2 to 3 years

The next test flight was only 17 months later carried out - 1 Stage ended prematurely firing.

The first commercial flight took place in December 1999.

Tragedy:

The problematic part of the program was only in preparation for the launch and the launch itself needed.

It should only be a transitional period to be active, for security reasons: 50 sec, to the ground station at a launch control over the interruption would have.

Despite the very different behavior of the Ariane 5 was nothing new about value.

Optimization:

Only 3 of 7 for a variables overflow examined - for the other 4 variables evidence existed that the values would remain small enough (Ariane 4).

This evidence was not for the Ariane 5 and this was not even understood.

Problem was with the of reuse of software!

Incredible - after 40 years of software-defect findings:

It was during program design assumes that only hardware failure may occur!

Therefore, the replacement computers also identical software. The system specification established that in case of failure of the computer is off and the replacement computer einspringt. A restart of a computer was not useful, since the redefinition of the flying height is too expensive.

PS: The attempt to establish new 4 Cluster satellites to launch, succeeded in July and August 2000 with two Russian launchers.


Discussion on all-or-nothing approach.

Life without worthwhile goals is not worth living

Here is Will Ross's take on this at REBT-Forum.

I'm not familiar with the quote, and I'm not sure what it means exactly. It could mean, as Rex suggests, that a life without worthwhile goals is not worth living. If that's the case, then it is both rational and irrational. It's rational because life is far more rewarding when we pursue worthwhile goals. It's irrational because it smacks of what David Burns calls "all-or-nothing thinking." It implies that life is either great or it sucks. There's no room for in-between. Helen Keller said something similar: "Life is a daring adventure or it is nothing." A noble sentiment,but too dichotomous for my tastes. My view is: By all means choose to pursue worthwhile goals, but don't make the mistake of killing yourself if you choose not pursue them.

Another possible meaning is that it's better to be dead than to be mediocre. This seems highly irrational. Given universal human fallibility, we're all mediocre in most respects (some people get to be outstanding in one or two areas, but even they are mediocre in most other areas of their lives). Let's accept our mediocrity and do all we can to enjoy life despite it. You can - if you want - choose to shoot for the stars, but don't expect to land on them. I refer once again to David Burns who gave a chapter of his book the greatest title I've ever seen: "Dare to be Average!"

Quote of the day

"I got 80 text messages today. One of my friends said to me, 'Dude, how many times a day do I have to see your ugly face?' - Micheal Phelps (on winning his 10th and 11th gold medal in the Olympics)