On Fri, 26 Feb 2016 07:54:26 +0100
isabella parakiss <izaberina_AT_gmail.com> wrote:
> the problem with factor is that any naive implementation
> will pale against the one in gnu coreutils.
>
> (gnu)
> $ time factor 1267650600228402790082356974917
> 1267650600228402790082356974917: 1125899906842679
> 1125899906842723 real: 0m1.576s, user: 0m1.570s, sys:
> 0m0.003s
>
> (yours with gmp)
> $ time ./factor 1267650600228402790082356974917
> 1267650600228402790082356974917: 1125899906842723
> 1125899906842679 real: 1m11.109s, user: 1m11.013s, sys:
> 0m0.013s
>
> (yours with tommath)
> $ time ./factor 1267650600228402790082356974917
> ^C interrupted after 20 minutes
>
> from at least 50x to more than 1000x slower than the gnu
> version. does this suck less?
>
>
> ---
> xoxo iza
>
Performance is not really something suckless
concerns itself about. They favour solutions
that are simpler to implement and maintain
but asymptotically slower. But in the case of
tommath, I don't think it is asymptotically
slower, at least not much, it is just makes
a hugh about of memory allocations. Which is
a very expensive operation.
It should however be noted, that factor(1) is
not intended to factorise huge numbers or brake
RSA numbers, in fact GNU factor will reject to
difficult numbers. It should just be able to
factor reasonably large numbers. I think 50 times
slower than GNU factor is acceptable, but 1000
times slower is not. Keep in mind though, that
the difference depends widely on the number that
is being factorised.
Received on Fri Feb 26 2016 - 09:01:25 CET