clear; 
Fq:=GF(13);
A2<x,y>:=AffineSpace(Fq,2);
Eaff:=Curve(A2,[y^2-(x^3+5)]);
Eproj:=ProjectiveClosure(Eaff); 
E:=EllipticCurve([Fq|0,5]);
// IsIsomorphic(E,Eaff); 
// generates error - must be projective
IsIsomorphic(E,Eproj);
#E; 
Points(E);