Ticket #5065 (closed defect: duplicate)
elliptic curve torsion subgroup doesn't know its identity
|Reported by:||boothby||Owned by:|
The torsion subgroup of an elliptic curve appears to be quite broken -- it barfs when trying to coerce in 0,
sage: E = EllipticCurve(1) sage: T = E.torsion_subgroup() sage: T(0) ... ... TypeError: Argument x (= 0) is of wrong type.
further, it returns a mysterious 1 when coercing in a 1
sage: a = T(1); a 1 sage: b = T.gens()-T.gens(); b (0 : 1 : 0) sage: a+b TypeError: unsupported operand parent(s) for '+': 'Abelian group of points on Elliptic Curve defined by y^2 + x*y + y = x^3 - 19*x + 26 over Rational Field' and 'Torsion Subgroup isomorphic to Multiplicative Abelian Group isomorphic to C6 x C2 associated to the Elliptic Curve defined by y^2 + x*y + y = x^3 - 19*x + 26 over Rational Field'
Yet, it's all cool with the original curve.
sage: E(0) (0 : 1 : 0) sage: E(1) ... ... TypeError: v (=(1,)) must have 3 components sage:
- Summary changed from elliptic curve torsion subgroup doesn't know it's identity to elliptic curve torsion subgroup doesn't know its identity
- Owner changed from was to davidloeffler
- Component changed from number theory to elliptic curves
- Status changed from new to closed
- Resolution set to fixed
- Report Upstream set to N/A