The LL_ARC_DISTANCE function returns a two-element vector containing the longitude and latitude [lon, lat] of a point a given arc distance (-p £ Arc_Dist £ p), and azimuth ( Az ), from a specified location Lon_lat0 . Values are in radians unless the keyword DEGREES is set.
This routine is written in the IDL language. Its source code can be found in the file
subdirectory of the IDL distribution.
The arc distance from Lon_lat0 . The value must be between -p and +p. To express distances in arc units, divide by the radius of the globe expressed in the original units. For example, if the radius of the earth is 6371 km, divide the distance in km by 6371 to obtain the arc distance.