Configurable step and max range

[lukepighetti]

We'd like to see a configurable yard step and maximum range. It appears that this is currently doing a 1 yard step and a 50,000 max range, meaning every calculation is performed 50,000 times. It would be nice if we could say do something like 50 yard step and 1000 yard range, turning that into 20 iterations.

[climb4hope]

The step of 1yd is for numeric integration to compute the trajectory accurately. In order to get the output with max and step, use the loop provided in the example file.