name Edwards curves parameter c parameter d coordinate x coordinate y satisfying x^2+y^2 = c^2(1+d x^2 y^2) addition x = (x1 y2+y1 x2)/(c(1+d x1 x2 y1 y2)) addition y = (y1 y2-x1 x2)/(c(1-d x1 x2 y1 y2)) doubling x = (x1 y1+y1 x1)/(c(1+d x1 x1 y1 y1)) doubling y = (y1 y1-x1 x1)/(c(1-d x1 x1 y1 y1)) negation x = -x1 negation y = y1 neutral x = 0 neutral y = c toweierstrass u = (c+y)/(c-y) toweierstrass v = 2 c (c+y)/(x(c-y)) a0 = 1/(1-d c^4) a1 = 0 a2 = 4/(1-d c^4)-2 a3 = 0 a4 = 1 a6 = 0 fromweierstrass x = 2 c u/v fromweierstrass y = c(u-1)/(u+1)