Create Function LatLonDistKM(
        @Lat1 Float, 
        @Lon1 Float, 
        @Lat2 Float, 
        @Lon2 Float
) Returns Float
/*
        Faster way to calculate distance in kilometers using Latitude & Longitude.  
This is accurate in KM to about 4.5 decimal places, except for very small distances.

NOTE: 57.295779513082323 = 180.0 / PI
 (converts Lat/Lon degrees to spherical radians)

Ref: The formula is derived from the Spherical Law of Cosines,

  --RBarryYoung, 31-Jan-2009
,                KM: 17-Feb-2009
*/ As
Begin
 Return 6357.0*acos(
    sin(@Lat1/57.295779513082323) 
        * sin(@Lat2/57.295779513082323) 
    + cos(@Lat1/57.295779513082323) 
        * cos(@Lat2/57.295779513082323) 
        * cos((@Lon2-@Lon1)/57.295779513082323)
)
End