def calculate_lyapunov(self):
        """
        Return the current Lyapunov Characteristic Number (LCN).
        Note that you need to call init_megno() before the start of the simulation.
        To get a timescale (the Lyapunov timescale), take the inverse of this quantity.
        """
        if self._calculate_megno==0:
            raise RuntimeError("Lyapunov Characteristic Number cannot be calculated. Make sure to call init_megno() after adding all particles but before integrating the simulation.")

        clibrebound.reb_tools_calculate_lyapunov.restype = c_double
        return clibrebound.reb_tools_calculate_lyapunov(byref(self))
Return the current Lyapunov Characteristic Number (LCN).
        Note that you need to call init_megno() before the start of the simulation.
        To get a timescale (the Lyapunov timescale), take the inverse of this quantity.