name Hessian curves parameter d coordinate x coordinate y satisfying x^3+y^3+1=3 d x y addition x = (y1^2 x2-y2^2 x1)/(x2 y2-x1 y1) addition y = (x1^2 y2-x2^2 y1)/(x2 y2-x1 y1) doubling x = y1(1-x1^3)/(x1^3-y1^3) doubling y = x1(y1^3-1)/(x1^3-y1^3) negation x = y1 negation y = x1 toweierstrass u = 12(d^3-1)/(d+x+y)-9 d^2 toweierstrass v = 36(y-x)(d^3-1)/(d+x+y) a0 = 1 a1 = 0 a2 = 0 a3 = 0 a4 = -27 d(d^3+8) a6 = 54(d^6-20 d^3-8) fromweierstrass x = (36(d^3-1)-v)/(6(u+9 d^2))-d/2 fromweierstrass y = (v+36(d^3-1))/(6(u+9 d^2))-d/2