n-torsion subgroups on Elliptic Curves defined on some field
if E an elliptic is defined on K, then E[n] is a subgroup of an Elliptic curve defined on an algebraic closure of K, its the set of points P of this curve whose order is dividing n
G = E.torsion_subgroup()
gives the torsion subgroup in E(K), but is there a method giving the E[n] ?
For example, for the Elliptic Curve y^2=x^3-2y^2=x^3-2 defined on Q
if we denote by alpha the cubic root of 2 and J a complex cubic root of unity, and O the point at infinity
E[2] = {O,(alpha,0), (alpha * J,0),(alpha * J^2,0)}
I tried the following
E = EllipticCurve(CC,[0,-2])
O = E(0)
O.division_points(2)
and got [pretty close but not the right result, and not in an algebraic form anyway]
[(0.000000000000000 : 1.00000000000000 : 0.000000000000000),
(1.25992104989487 : 0.000000000000000 : 1.00000000000000)]
thanks