Re: New GP function ellrank (2-descent)

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

On Tue, Feb 16, 2021 at 02:47:51PM +0000, John Cremona wrote:
> Some other comments: using quartic reduction, the first quartic q1 you
> gave reduces to the quartic with coefficients
> (1364,-292,12837,6916,41748) -- this is q1(x-58) / 65278768^2.  On
> this, x=-339591/68258 gives a rational point.

I rechecked, what is printed is the curve before reduction.
After reduction the curve is
1364*x^4+10620*x^3+43821*x^2+98408*x+126416
with x=-476107/68258

The difference (-56 vs -58) seems due to a bad choice of representative
([0,b] instead of [-b/2,b/2]).

Cheers,
Bill.