Function: ellheight
Section: elliptic_curves
C-Name: ellheight0
Prototype: GGD2,L,p
Help: ellheight(e,x,{flag=2}): canonical height of point x on elliptic curve
 E defined by the vector e. flag is optional and selects the algorithm used
 to compute the archimedean local height. Its meaning is 0: use
 theta-functions, 1: use Tate's method, 2: use Mestre's AGM

