Prime factor of 300 000 000 000?

Question

I need to find out the prime factors of over 300 billion. I have a function that is adding to the list of them...very slowly! It has been running for about an hour now and i

Answer 1

Here is an XSLT solution!

This XSLT transformation takes 0.109 sec.

This transformation produces the correct result (the maximum prime factor of 600851475143) in just 0.109 sec.:

6857

The transformation uses the f:sqrt() and f:isPrime() defined in FXSL 2.0 -- a library for functional programming in XSLT. FXSL is itself written entirely in XSLT.

f:isPrime() uses Fermat's little theorem so that it is efficient to determine primeality.