There is a function describing the characterisic elevation of ISS seen from an observers horizon. Calculating of an elevation at one time is pretty expensive. So I wanna try to avoid naive iterating over time. I look for a efficient way to get the zero crossings which corresponds to rise and set.
Which method could I take to calculate the zero crossings from now to the future (positive direction). For example a task would be: What are the next three rises, transits and sets from now on? Thanks.