Calculates Fibonacci to the limit you specify.
Can calculate fib(500) in roughly half a second.
You'll need the Math::BigInt module. As far as I know it comes default, but if you don't have it, use cpan
"sudo cpan Math::BigInt"
#!/usr/bin/perl
use warnings; use strict;
use Math::BigInt;
my $n = 2; my $a;
my @nums = qw(0 1);
print "Calculate Fibonacci sequence to [number]: ";
my $max = <STDIN>;
while ($n < $max) {
$a = Math::BigInt->new($nums[$n-1] + $nums[$n-2]);
push(@nums, $a);
$n++;
printf("%s\n", $a);
}