MapBasic Code. Copy/Paste if needed.

include "GC_Constants.def" include "GC_Distance.def" '====================================================================== function GreatCircleDistance (    byval fLon0 as float,     'Origin longitude    byval fLat0 as float,     'Origin latitude    byval fLon1 as float,     'Destination longitude    byval fLat1 as float,     'Destination latitude    byval fRadius as float)   'Radius of sphere    as float                  'Distance (in radius units) 'Returns the great circle distance between two points. Distance units 'are the same as those of the radius. This is equivalent to MapInfo's 'Distance() function. '---------------------------------------------------------------------- dim a, b, c as float dim lat0, lon0, Lat1, Lon1 as float    lat0 = fLat0 * DEG2RAD    lon0 = fLon0 * DEG2RAD    lat1 = fLat1 * DEG2RAD    lon1 = fLon1 * DEG2RAD    a = (sin((lat1-lat0)/2))^2    b = (sin((lon1-lon0)/2))^2    c = (a + cos(lat1) * cos(lat0) * b)^0.5    c = 2 * asin(c)    GreatCircleDistance = c * fRadius end function