Alain SMEJKAL on Fri, 08 Jun 2007 23:31:27 +0200

 Re: fun RSA-like number

```> I found this funny RSA challenge-like number:
>
> ?
2232910609332187886082982422994038035269933607980867743982829475969531575124
064916213584339209041654201264049086377750345171525039801

Hello all,

More than fun, this number can prove efficiency of GP scripts.
Here, flags used with factorint indicates that internal Pollard-Brent Rho or
SQUFOF algorithm is used for factorization.
Using a classical Pollard-Brent Rho GP script implementation, factorization
time can be largely reduced (maybe much more with gp2c).
Thanks for this handy, reliable and fast software !

gp > for (i=1,100,y=factor(n))
time = 3,234 ms.
gp > for (i=1,100,y=factorint(n,11))
time = 3,219 ms.
gp > for (i=1,100,y=rhobrent(n))
time = 79 ms.

> Another one, different in nature:
>
> ?
3153627868433467319941213011803229193910650395093119880070890986935182829794
577898323490044799996388232993633159912821646956999337547873980207

Here, Rho-Brent does not work and time can be saved using factorint
restricted to ECM.
However it is really funny to find so large factors so fast by ECM.

gp > y=factor(n)
time = 42,422 ms.
gp > y=factorint(n,5)
time = 47 ms.

Regards,
Alain

```