What's the function of "virtual int InitRunning(void){ return 1; }" in class FGEngine?

[theorynice]

Hi, everyone. Recently, I wanted to utilize MCTS (Montecarlo tree search) to plan the plane's motion. This method needs to store the states of the previous time. When it finishes the forward search, we should restore the states at the time it starts to search. Based on the project "https://github.com/nico1as/gym-jsbsim", I am close to success. However, when I frequently call the get_state() and set_state(), for example, once time every jsbsim runs 12 timesteps, I found the trajectory from using MCTS(call the set_state() at each timestep along an episode) is not the same as the trajectory when I restore the states at the beginning and run jsbsim normally with the same action series (only call the set_state() one time at the beginning of this episode). The reason I think is that the function get_ready_state() in class FGPropulsion is called when set_state() is called. The thing confusing me is how the get_ready_state() affects the result when I call it at each timestep. When I call it at low frequency in MCTS, the two trajectories are almost the same.