lambda1 = -(t-1)^3*(t+3); lambda2 = -16*t; e=ellinit([0,-lambda1-lambda2, 0,lambda1*lambda2,0]); g = elladd(e,[x,y],[x,y])[1] -x \\ g = substpol(g,y^2, x*(x-lambda1)*(x-lambda2)) \\ g = numerator(g) P = [4*(t-1)^2,4*(t-1)^2*(t+1)^2] ellisoncurve(e,P)