Function: ellintegralmodel
Section: elliptic_curves
C-Name: ellintegralmodel
Prototype: GD&
Help: ellintegralmodel(E,{&v}): given an elliptic curve E defined
 over a number field or Qp, returns an integral model. If v is present,
 sets the variable v to the corresponding change of variable.
Doc: Let $E$ be an \kbd{ell} structure over a number field $K$ or $\Q_p$.
 This function returns an integral model. If $v$ is present, sets
 $v = [u,0,0,0]$ to the corresponding change of variable: the return value is
 identical to that of \kbd{ellchangecurve(E, v)}.
 \bprog
 ? e = ellinit([1/17,1/42]);
 ? e = ellintegralmodel(e,&v);
 ? e[1..5]
 %3 = [0, 0, 0, 15287762448, 3154568630095008]
 ? v
 %4 = [1/714, 0, 0, 0]
 @eprog
