ellj

Function: ellj
Section: elliptic_curves
C-Name: jell
Prototype: Gp
Help: ellj(x): elliptic j invariant of x.
Doc:
 elliptic $j$-invariant. $x$ must be a complex number
 with positive imaginary part, or convertible into a power series or a
 $p$-adic number with positive valuation.