Re: formal ellinit

[Karim Belabas <Karim.Belabas@math.u-bordeaux1.fr>]

* Bill Allombert [2012-07-17 14:07]:
> On Tue, Jun 12, 2012 at 11:53:40PM +0200, Karim Belabas wrote:
> > * Bill Allombert [2012-06-11 14:06]:
> > > I found a way to do a formal ellinit which is sometimes useful:
> > > 
> > > ? a6;a4;a3;a2;a1;E=ellinit([a1,a2,a3,a4,a6],1);
> > > ? ##
> > >   ***   last result computed in 0 ms.
> > > 
> > > This is useful because the more straightforward
> > > a1;a2;a3;a4;a6;ellinit([a1,a2,a3,a4,a6],1);
> > > does not really work (much much slower).
> > 
> > I committed a workaround for the original problem in master:
> 
> This is very useful, thanks.
> However your work around only seems to work in char 0, 2 and 3.
> 
> ? E=ellinit([a1,a2,a3,a4,a6]*Mod(1,5))
>   *** ellinit: the PARI stack overflows !
>   current stack size: 32000000 (30.518 Mbytes)

A problem in isinexactall(): one "simple" coefficient in the wrong
degree was enough to decide that the whole polynomial was "simple"
and that the naive RgX_gcd_simple() was sufficient.

Fixed in master. Thanks !

    K.B.
-- 
Karim Belabas, IMB (UMR 5251)  Tel: (+33) (0)5 40 00 26 17
Universite Bordeaux 1          Fax: (+33) (0)5 40 00 69 50
351, cours de la Liberation    http://www.math.u-bordeaux1.fr/~belabas/
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