(Y/Z)² = 1 + d(X/Z)²(Y/Z)² // (-X² + Y²)/Z² = 1 + (dX²Y²)/Z⁴ // (-X² + Y²)*Z² = Z⁴ + dX²Y² var lhs, rhs field.Element lhs.Subtract(&YY, &XX).Multiply(&lhs, &ZZ) rhs.Multiply(d, &XX).Multiply(&rhs, &YY).Add(&rhs, &ZZZZ) if lhs.Equal(&rhs) != 1 { t.Errorf("X, Y, and Z do not specify a point on the curve\nX = %v\nY = %v\nZ = %v", p.x, p.y, p.z) } // xy = T/Z lhs.Multiply(&p.x, &p.y) rhs.Multiply(&p.z, &p.t) if lhs.Equal(&rhs) != 1 { t.Errorf("point %d is not valid\nX = %v\nY = %v\nZ = %v", i, p.x, p.y, p.z)...