Re: weird behaviour of rnfequation

[Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>]

On Wed, Dec 15, 2010 at 05:25:38PM +0100, Luis Felipe Tabera Alonso wrote:
> Hi all,
> 
> I have encounter the following behaviour in pari with the version that comes 
> with sage. I have confirmed that this happens in pari/gp stable as released by 
> Debian (2.3.5) and with the development version downloaded from the web (2.4.3 
> (alpha)), both 64 bits.
> 
> The problem is the following, I have the following dummy rnfequation:
> 
> ? f = (y^17-1)/(y-1);
> ? g = Mod(1,f)*x+Mod(y^6,f);                                                                       
> ? rnfequation(f,g,1);                                                                 
>   *** rnfequation: the PARI stack overflows !                                                         
>   current stack size: 8000000 (7.629 Mbytes)
>   [hint] you can increase GP stack with allocatemem()

Hello Luis,

This is certainly a bug. rnfequation use a modular algorithm to compute 
rnfequation(f,g,1) which unfortunately diverge here.

I have recorded this issue in our bug tracking system as bug number 1151
<http://pari.math.u-bordeaux.fr/cgi-bin/bugreport.cgi?bug=1151>
so we do not forget about it.

Cheers,
Bill.