Explicit computation of the modular parametrization of elliptic curves over function fields by Drinfeld modular curves

Abstract

Let q be a prime power and E a non-isotrivial elliptic curve over Fq(T ) given by a Weierstrass model. We survey the construction, with an explicit point of view, of the modular parametrization of E by the associated Drinfeld modular curve. We then prove a formula that allows us to evaluate this modular parametrization at cusps and we produce an explicit method to compute these values. Finally we illustrate our results with several examples in characteristic 2 and 3.