Invariant differential on an elliptic curve (source code)

= Invariant differential on an elliptic curve

= Elliptic invariant differential
{synonym}

On $y^2=x^3+ax+b$ in characteristic other than two, the differential
$$
\omega=\frac{dx}{2y}
$$
extends regularly and without zeros across the point at infinity. Translation by every point preserves it.