Seems like we could add a new option to x2sys_cross that would skip crossings where the azimuths at the cross points differ by less than cutoff, like -S excludes crossings when the ship was moving too slowly to be mapping anything. Maybe -Ecutoff would work. The code has to check for line orientation, not azimuth, and then compute difference in orientation and if less than cutoff we skip it. I don’t think there is a good default cutoff value so it needs t one set. John, I am busy with other non-GMT things so do you mind turning this into a feature request on GitHub.
As for the error calculations. Should it not be done by x2sys_solve instead?