UTM (Universal Transverse Mercator) co-ordinates are an approximate mapping from the Earth's surface to flat regions. If your co-ordinates are in UTM then you can use pythagoras to calculate the distance between points:
distance = sqrt( (x1 - x2)^2 + (y1 - y2)^2 )
The distance between two sets of latitude and longitude co-ordinates are more interesting. The Haversine formula is a beautiful way to calculate these, combining both simplicity and accuracy over small distances:
dlon = lon2 - lon1 dlat = lat2 - lat1 a = sin^2(dlat/2) + cos(lat1) * cos(lat2) * sin^2(dlon/2) c = 2 * arcsin(min(1,sqrt(a))) d = R * c
Tarim / March 2008 / for Swarm MediaSandbox project