#!/usr/bin/perl
###
#generate $ARGV[0] digits of pi.
#the algorithm is here:
#http://crd.lbl.gov/~dhbailey/
####
#written by Pete_I with help from BillN1VUX(from freenode)
####
#edited to make more efficient use of memory

use strict;
use warnings;
use Math::BigFloat;

my $DIGS = $ARGV[0] || 50;
Math::BigFloat->div_scale($DIGS+10);

my $pi = Math::BigFloat->new();
for(0 .. $DIGS) {
 $pi->badd( get_digit($_) );
}
print "\n", $pi->round($DIGS) . "\n";

sub get_digit {
 my $k = Math::BigFloat->new(shift);
 ( 1 / 16 ** $k ) *
 (
  (4 / (8 * $k + 1))-
  (2 / (8 * $k + 4))-
  (1 / (8 * $k + 5))-
  (1 / (8 * $k + 6))
 )
}

__DATA__
digits of pi to compare accuracy
3.14159265358979323846264338327950288419716939937510582097494459230781
+6406286208998628034825342117067982148086513282

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