RHOTHETA - the name refers to the (for me) mind boggling maths
involved in circular triangles.

RHOTH.OPL prompts for Latitude and Longitude (or in Great Britain you
can enter the OS National Grid Ref NGR ) and then asks you for
other lat/long or NGRs.  It then calculates the NGR from the remote
lat/long, or the lat/long from the remote NGR, and displays the
distance in miles, nautical miles and kilometers on the great circle
route, and the DIRECTION in degrees from true North.

Useful if you are a radio ham ... actually.

The program is rough and ready.  It has nevertheless taken me about
8 hours to get it this far from a rather unstructured and undocumented
BASIC listing I have had for many years.

It could be a lot smaller.  It needs a more friendly user interface.

...one day... praps.            Carl Littlejohns GW8UGJ csljohns@cix
                                GW8UGJ @ GB7OAR       April 1993