Function calculate_nutation_frequency 

pub fn calculate_nutation_frequency(
    spin_rate_rad_s: f64,
    spin_inertia: f64,
    transverse_inertia: f64,
    stability_factor: f64,
) -> f64

Fast-mode (nutation) angular frequency in rad/s: phi_fast = (Ix p / 2 Iy)(1 + sqrt(1 - 1/Sg)).