Hi all,

I've been trying to come up with a way to calculate factorials of very large numbers (example: of 2032597) and currently I'm stuck on the implementation of the Stirling's approximation. I tried using bignum but I keep getting an error stating: "Can't use an undefined value as an ARRAY reference at C:/Perl/../Calc.pm"

In this approximation, $exp evaluates to ~2.8e11938980. Is this number too large to be used in perl? 

use Math::Trig;
use bignum;
sub factorial
{
  my $n = @_;
  my $root = sqrt($n*2*pi);
  my $exp = ($n/exp(1))^$n;
  my $result =$root*$exp;
  return $result;
}

my $b = 2032597;
my $r = Math::BigInt->new(factorial($b));
print "b is $b\n";
print "the calculated result is $r\n";

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In reply to Operations with Extremely Large Numbers by jjw017

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