Re: elltors() bug

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

[Igor:]
> ? elltors(ellinit([0,1,0,0,1/3]))
>   ***   bug in torsell (bug1), please report
> ? elltors(ellinit([0,1,0,0,1/5]))
>   ***   not an integer argument in an arithmetic function
> 
> Could it be that elltors() can only deal with integer-coefficient
> curves?

It is. The current "solution" is to use an integral model (e.g ellglobalred +
ellchangecurve). I'm updating the documentation...

  Karim.

P.S: From a cursory glance at the code, elltors follows Nagell-Lutz approach,
which is a disaster when the discriminant gets big. Computing modulo small
primes of good reduction should be infinitely more efficient. [Anybody
implemented that already ?]
__
Karim Belabas                    email: Karim.Belabas@math.u-psud.fr
Dep. de Mathematiques, Bat. 425
Universite Paris-Sud             Tel: (00 33) 1 69 15 57 48
F-91405 Orsay (France)           Fax: (00 33) 1 69 15 60 19
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PARI/GP Home Page: http://hasse.mathematik.tu-muenchen.de/ntsw/pari/