23 #
 24 # pi*($d/2)**2    in circle
 25 # ------------ ~ ----------- ~ pi/4
 26 #  $d**2          in total
 27 #
 28 
 29 
 30 
 31 use strict;
 32 use warnings;
 33 
 34 my $d = 1000;#diameter
 35 my $no_total = 1000000;#number of points
 36 my $no_in=0;
 37 
 38 sub gen_xy { ( int(rand($d)),int(rand($d)) ); }
 39 
 40 sub in_circle {
 41     my ($x,$y) = @_;
 42     ($x - $d/2)**2 + ($y - $d/2)**2 <= ($d/2)**2
 43     ? 1
 44     : 0;
 45 }
 46 
 47 
 48 $no_in += in_circle gen_xy
 49     for 1..$no_total;
 50 
 51 warn "Pi approx: ". (  $no_in/$no_total ) *4  ;