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Running for 10,000,000 twice I got 3.1405 the first run, and 3.1424 the second. (for an average of 3.1415) It's quite likely your rand() isn't perfect. (neither is mine 10,000,000 runs should give me a digit or two more accuracy).

Anyway, here is my favorite approximation for pi, mainly because it only uses the number 2. Even though two is normally a computer friendly number, this algorithm isn't, because it also uses sqrt's. With my perl, 14 iterations is gives the maximum accuracy: 3.14159265480759

```#!/usr/bin/perl -w
use strict;

print "Enter how many iterations:\n";
chomp(my \$i = <>);

my \$x = \$i - 1;
my \$y = sqrt(2);
do { \$y = sqrt(2 + \$y) while (--\$x);
\$y = sqrt(2 - \$y);
} if \$x;

my \$z = \$y * (2 ** \$i);

print "Pi is close to: \$z\n";

So, while not the best, but I have some strange affinity to it. :)

Ciao,
Gryn

p.s. Sorry for the cryptic code for a quick decrypt its: (2**n)*sqrt(2-sqrt(2+sqrt(2+sqrt(2+sqrt(2))))) with the number of 2's inside the sqrt equaling n.

In reply to Accuracy of Random Pi by gryng
in thread Pi calculator by Fingo

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