source 2013 Oliveira--López--Aranha--Rodríguez-Henríquez "Lambda coordinates for binary elliptic curves"; database entry contributed by Chitchanok Chuengsatiansup parameter a21 assume a21 = a2 + 1 parameter a226 assume a226 = a2^2 + a6 compute A = Z1^2 compute B = L1 + Z1 compute C = L1 B compute D = a2 A compute E = C + D compute F = L1 + X1 compute G = F^2 compute H = A^2 compute X3 = E^2 compute Z3 = E A compute L3 = G (G + E + A) + a226 H + X3 + a21 Z3