# Properties

 Base field $$\Q(\sqrt{-1})$$ Label 2.0.4.1-100.2-a6 Conductor $$(10)$$ Conductor norm $$100$$ CM no base-change yes: 20.a4,80.b4 Q-curve yes Torsion order $$12$$ Rank $$0$$

# Related objects

Show commands for: Magma / Pari/GP / SageMath

## Base field $$\Q(\sqrt{-1})$$

Generator $$i$$, with minimal polynomial $$x^{2} + 1$$; class number $$1$$.

sage: x = polygen(QQ); K.<i> = NumberField(x^2 + 1)

gp: K = nfinit(i^2 + 1);

magma: R<x> := PolynomialRing(Rationals()); K<i> := NumberField(R![1, 0, 1]);

## Weierstrass equation

$$y^2+\left(i+1\right)xy+\left(i+1\right)y=x^{3}+\left(-i-1\right)x-i$$
sage: E = EllipticCurve(K, [i + 1, 0, i + 1, -i - 1, -i])

gp: E = ellinit([i + 1, 0, i + 1, -i - 1, -i],K)

magma: E := ChangeRing(EllipticCurve([i + 1, 0, i + 1, -i - 1, -i]),K);

This is a global minimal model.

sage: E.is_global_minimal_model()

## Invariants

 $$\mathfrak{N}$$ = $$(10)$$ = $$\left(i + 1\right)^{2} \cdot \left(-i - 2\right) \cdot \left(2 i + 1\right)$$ sage: E.conductor()  magma: Conductor(E); $$N(\mathfrak{N})$$ = $$100$$ = $$2^{2} \cdot 5^{2}$$ sage: E.conductor().norm()  magma: Norm(Conductor(E)); $$\mathfrak{D}$$ = $$(100)$$ = $$\left(i + 1\right)^{4} \cdot \left(-i - 2\right)^{2} \cdot \left(2 i + 1\right)^{2}$$ sage: E.discriminant()  gp: E.disc  magma: Discriminant(E); $$N(\mathfrak{D})$$ = $$10000$$ = $$2^{4} \cdot 5^{4}$$ sage: E.discriminant().norm()  gp: norm(E.disc)  magma: Norm(Discriminant(E)); $$j$$ = $$\frac{21296}{25}$$ sage: E.j_invariant()  gp: E.j  magma: jInvariant(E); $$\text{End} (E)$$ = $$\Z$$ (no Complex Multiplication ) sage: E.has_cm(), E.cm_discriminant()  magma: HasComplexMultiplication(E); $$\text{ST} (E)$$ = $\mathrm{SU}(2)$

## Mordell-Weil group

Rank: $$0$$

sage: E.rank()

magma: Rank(E);

sage: gens = E.gens(); gens

magma: gens := [P:P in Generators(E)|Order(P) eq 0]; gens;

sage: E.regulator_of_points(gens)

magma: Regulator(gens);

## Torsion subgroup

Structure: $$\Z/2\Z\times\Z/6\Z$$ sage: T = E.torsion_subgroup(); T.invariants()  gp: T = elltors(E); T[2]  magma: T,piT := TorsionSubgroup(E); Invariants(T); $\left(-i + 1 : -2 i - 1 : 1\right)$,$\left(-\frac{1}{2} i : -\frac{1}{4} i - \frac{3}{4} : 1\right)$ sage: T.gens()  gp: T[3]  magma: [piT(P) : P in Generators(T)];

## Local data at primes of bad reduction

sage: E.local_data()

magma: LocalInformation(E);

prime Norm Tamagawa number Kodaira symbol Reduction type Root number ord($$\mathfrak{N}$$) ord($$\mathfrak{D}$$) ord$$(j)_{-}$$
$$\left(i + 1\right)$$ $$2$$ $$3$$ $$IV$$ Additive $$-1$$ $$2$$ $$4$$ $$0$$
$$\left(-i - 2\right)$$ $$5$$ $$2$$ $$I_{2}$$ Non-split multiplicative $$1$$ $$1$$ $$2$$ $$2$$
$$\left(2 i + 1\right)$$ $$5$$ $$2$$ $$I_{2}$$ Non-split multiplicative $$1$$ $$1$$ $$2$$ $$2$$

## Galois Representations

The mod $$p$$ Galois Representation has maximal image for all primes $$p < 1000$$ except those listed.

prime Image of Galois Representation
$$2$$ 2Cs
$$3$$ 3B.1.1

## Isogenies and isogeny class

This curve has non-trivial cyclic isogenies of degree $$d$$ for $$d=$$ 2, 3 and 6.
Its isogeny class 100.2-a consists of curves linked by isogenies of degrees dividing 12.

## Base change

This curve is the base-change of elliptic curves 20.a4, 80.b4, defined over $$\Q$$, so it is also a $$\Q$$-curve.