Re: Ratpoint

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

On Sat, Dec 17, 2016 at 03:33:54PM +0000, John Cremona wrote:
> On 17 December 2016 at 14:40, Bill Allombert
> <Bill.Allombert@math.u-bordeaux.fr> wrote:
> > On Sat, Dec 17, 2016 at 08:11:27AM +0000, Jenn Macleod wrote:
> >> Does anybody have a Pari implementation of Michael Stoll's ratpoint.c code?
> >>
> >> This would be of great use in my doodlings.
> >
> > Denis Simon descent code include one:
> > <http://www.math.unicaen.fr/~simon/ellQ.gp>
> > function ratpoint.
> >
> 
> This is misleading.  Denis Simon's code needs a function to find
> solutions to y^2=f(x) where f is integral of degree 3 or 4, and he
> provides a function called ratpoint() to do this.  It is *not* the
> same as Michael Stoll's independent C program of that name.  Stoll's
> program ratpoints.c (which he developed from old code by Elkies) is
> more general in several ways (deg(f) essentially arbitrary) and also
> probably much faster.

This is very true. However Denis functions is not limited to degree
3/4 polynomials.

Cheers,
Bill.