Re: new GP function ellisomat

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

On Thu, Aug 06, 2015 at 03:09:27PM +0200, Bill Allombert wrote:
> Also I am not sure what is the best way to compute the dual isogenies
> (from E_i to E).

I managed to do it. Now ellisomat also return the dual isogenies.

? E = ellinit("14a1");
? [L,M]=ellisomat(E);
? L[2]
%5 = [[-675/16,6831/32],[x^3+3/4*x^2+19/2*x-311/12,1/2*x^4+(y+1)*x^3+(y-4)*x^2+(-9*y+23)*x+(55*y+55/2),x+1/3],[1/9*x^3-1/4*x^2-141/16*x+5613/64,-1/18*x^4+(1/27*y-1/3)*x^3+(-1/12*y+87/16)*x^2+(49/16*y-48)*x+(-3601/64*y+16947/512),x-3/4]]

L[2][3] is the dual of L[2][2]

Cheers,
Bill.