These functions are for elliptic curves over any (exact) field.
This function returns a polynomial in two variables, T1 + T2 + ..., which expresses the formal group law associated to addition on E, up to precision prec. (More precisely, it contains the terms which have total degree less than or equal to prec.)The formal variables T1 and T2 may be identified with the function -x/y on E, where x and y are the standard affine coordinates on E. (Note that this function is a local parameter in a neighbourhood of OE.)
This function returns the homomorphism of formal groups associated to the isogeny phi, represented as a power series in one variable up to precision prec. As in FormalGroupLaw, this is in terms of the parameter -x/y on each curve.
Precision: RngIntElt Default: 10
This function returns the formal logarithm for the elliptic curve E as a power series f(T), where the parameter T is the function -x/y on E. (This is the same parameter used in FormalGroupLaw).The function also returns a point P(T) on E with coordinates in a Laurent series ring with generator T, which again corresponds to -x/y. Thus P(T) is a formal parametrisation of E in a neighbourhood of OE.