Function: ellap
Section: elliptic_curves
C-Name: ellap0
Prototype: GGD0,L,
Help: ellap(e,p,{flag=0}): computes a_p for the elliptic curve e using
 Shanks-Mestre's method. flag is optional and can be set to 0 (default) or 1
 (use Jacobi symbols)

