How can I speed up a script that iterates over a large range (600 billion)?

[Terry Reedy]

On 6/21/2011 8:00 PM, Paul Rubin wrote:
> Terry Reedy<tjreedy at udel.edu>  writes:
>>> efficient implementation will allow a solution to be obtained on a
>>> modestly powered computer in less than one minute."
>> If something really takes a minute in C,
>> allow yourself at least 10 minutes or even more with plain CPython.
>
> No.

No what? My conditional statement is correct. It turns out not to apply 
here. Great.

> The idea of the Euler problems is to think up sane algorithms to
> solve them, not micro-optimize or use low level languages on crappy
> algorithms.
>
>       n=600851475143
>       for d in xrange(2,n):
>         if d*d>  n: break
>            while n%d == 0: n //= d
>       print n
>
> finishes on my laptop with no noticable pause.

If the best C program for a problem takes 10 seconds or more, then 
applying the same 1 minute limit to Python is insane, and contrary to 
the promotion of good algorithm thinking.

-- 
Terry Jan Reedy