Function: hyperelldisc
Section: elliptic_curves
C-Name: hyperelldisc
Prototype: G
Help: hyperelldisc(X): X being a nonsingular hyperelliptic model of a curve,
 defined over a field of characteristic distinct from 2, returns its discriminant.
 X can be given either by a squarefree polynomial P such that
 X:y^2=P(x) or by a vector [P,Q] such that X:y^2+Q(x)*y=P(x) and Q^2+4P is
 squarefree.
Doc:
 $X$ being a nonsingular hyperelliptic model of a curve,
 defined over a field of characteristic distinct from 2, returns its discriminant.
 $X$ can be given either by a squarefree polynomial $P$ such that
 $X$ has equation $y^{2} = P(x)$ or by a vector $[P,Q]$ such that
 $X$ has equation $y^{2} + Q(x)\*y = P(x)$ and $Q^{2}+4\*P$ is squarefree.
 \bprog
 ? hyperelldisc([x^3,1])
 %1 = -27
 ? hyperelldisc(x^5+1)
 %2 = 800000
 @eprog
