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#1 2006-04-23 15:04:00

ryos
Member
Registered: 2005-08-04
Posts: 394

Pi, the long way around

The blogger "ridiculous fish" has implemented a very novel approach to cutting out comment spam (and much better than the "distorted image" method). I thought it was both interesting and cool. Have a look:

http://ridiculousfish.com/blog/?p=23

Last edited by ryos (2006-04-23 15:04:19)


El que pega primero pega dos veces.

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#2 2006-04-23 21:33:02

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,529

Re: Pi, the long way around

So far they have:
    * 1359 / 2475 pairs were relatively prime.
    * pi is approximately 3.30562434615


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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#3 2006-04-24 01:08:56

krassi_holmz
Real Member
Registered: 2005-12-02
Posts: 1,908

Re: Pi, the long way around

Pretty interesting.


IPBLE:  Increasing Performance By Lowering Expectations.

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#4 2006-04-24 01:35:19

krassi_holmz
Real Member
Registered: 2005-12-02
Posts: 1,908

Re: Pi, the long way around

Here's a Mathematica fuction which makes n tests with numbers less than b:

PPr[n_, b_] :=
  (
    c = 0;
    Do[If[GCD[Random[Integer, {1, b}], Random[Integer, {1, b}]] == 1, c++;], {i, 1, n}];
    c/n
    )

6/pi^2=0.607927


As you see, this method is unusable, because for approximately 3 digits of 6/pi^2 you need >10^6 tests.


IPBLE:  Increasing Performance By Lowering Expectations.

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#5 2006-04-24 02:19:38

Patrick
Real Member
Registered: 2006-02-24
Posts: 1,005

Re: Pi, the long way around

well, one million comments, that's not that much roll

He's just trying to make a laugh of spam smile (but ruining his fun is great too wink)


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#6 2006-04-24 12:04:09

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,529

Re: Pi, the long way around

Good work, krassi!

Another (of the many) ways to calculate π would be to pick a random coordinate in a square, then see if it falls within the inscribed circle (using x²+y²=r²).


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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