If it's easier for you to visualize think of time of flight in terms of length/time be my guest..
Using time of flight puts the entire event in time units and there is no need to break it into length sectors.
What the ballistic programs return from there inputs is based on there programming. Some on the internet simply use polynomial fitting curves and some others use algorhythms using stepped difference equations. Hopefully they will use one out of the NAG library that is generally accepted.if they are using fitting curves hopefully they have tested it against these to test for errors that are inherent in large calculations.
Fortunately the degree of precision needed dealing with guns and bullets isn't inherently high in the machine its self
