English
The polynomial Z in the projective equation is the homogeneous cubic that encodes the Z-coordinate of the Weierstrass equation in projective variables X,Y,Z.
Русский
Полином Z в проективном уравнении кодирует Z-координату вахваты уравнения Вейерштрасса в проективных переменных X,Y,Z.
LaTeX
$$$W'.polynomialZ = Y^{2} + a_1 X Y + a_3 Y Z - (a_2 X^{2} + 2 a_4 X Z + 3 a_6 Z^{2})$$$
Lean4
/-- The partial derivative `W_Z(X, Y, Z)` with respect to `Z` of the polynomial `W(X, Y, Z)`
associated to a Weierstrass curve `W` in projective coordinates. -/
noncomputable def polynomialZ : MvPolynomial (Fin 3) R :=
pderiv z W'.polynomial