Function: hyperellordinate
Section: elliptic_curves
C-Name: hyperellordinate
Prototype: GG
Help: hyperellordinate(H,x): y-coordinates corresponding to x-ordinate x on
 hyperelliptic curve H.
Doc:
 gives a 0, 1 or 2-component vector containing
 the $y$-coordinates of the points of the curve $H$ having $x$ as
 $x$-coordinate.

