Function: hyperellcharpoly
Section: elliptic_curves
C-Name: hyperellcharpoly
Prototype: G
Help: hyperellcharpoly(X): X being a non-singular hyperelliptic curve defined
 over a finite field, return the characteristic polynomial of the Frobenius
 automorphism.  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 non-singular hyperelliptic curve defined over a finite field,
 return the characteristic polynomial of the Frobenius automorphism.
 $X$ 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 $Q^2+4\*P$ is squarefree.
