All you need in order to generate the next Fibonacci number
is the last two; why are you storing all
of them? (Also, why not use strict
Here's one way; I presented something similar in Fibonacci numbers with lvalues. I give this one as I think it presents an interesting reminder of how "parallel assignment" is useful.
The modification to use Math::BigInt would be easy but obfuscatory for this example.
my ($a,$b)=(1,2); # Start sequence at 1,2 like in code
($a,$b) = ($b,$a+$b);
Save memory, easier to read, etc.