def f(t0, u_, k):
du_kep = func_twobody(t0, u_, k)
ax, ay, az = atmospheric_drag_exponential(
t0, u_, k, R=R, C_D=C_D, A_over_m=A_over_m, H0=H0, rho0=rho0
)
du_ad = np.array([0, 0, 0, ax, ay, az])
return du_kep + du_ad
def J2_and_drag(t0, state, k, J2, R, C_D, A_over_m, H0, rho0):
return J2_perturbation(t0, state, k, J2, R) + atmospheric_drag_exponential(
t0, state, k, R, C_D, A_over_m, H0, rho0
)