def deriv_v_φ_func(*, Z_2, deriv_v_r, dderiv_B_φ, norm_kepler, v_r, X, B_θ):
    """
    Compute the derivative of v_φ
    """
    return Z_2 - deriv_v_r * v_r / (2 * norm_kepler) + dderiv_B_φ * B_θ * X / (
        2 * norm_kepler)
