You got good answer, yet.

I would just add the possibility to take yet optimized code from CPAN: Math::Prime::Util (or Math::Prime::Util::GMP directly for big numbers.. but see also..)

From examples: 

# Project Euler, problem 3 (Largest prime factor)

use Math::Prime::Util qw/factor/;
use bigint;  # Only necessary for 32-bit machines.
say 0+(factor(600851475143))[-1]

[download]

PS wow it returns in no time!: 

perl -Mbigint -E "use Math::Prime::Util::GMP qw(factor); say 0+(factor
+(600851475143600851475143600851475143))[
-1]"

999999000001

# ~1 second to get the largest factor of:
# 60085147514360085147514360085147514300851475143008514751430085147514
+30085147514300851475143

834789126661809633627036527926883609177018602883402075695455196267

[download]

L*

There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

In reply to Re: Avoid keeping larger lists in Memory by Discipulus
in thread Avoid keeping larger lists in Memory by pr33

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