Distance Calculation

The distance calculation is done using the `geod' program, which is part of the `PROJ' system available from the U.S. Geological Survey at ftp://kai.er.usgs.gov/pub/. It should be quite accurate.

I have a simpler formula for great-circle distance which assumes a spherical earth; I think that can't cause more than 0.2% error. My perl program for doing this calculation is freely available. It also computes the initial heading of the great-circle path. If you have any questions about it, send me e-mail.

Back to the distance server.