Get the initial bearing (direction; azimuth) to go from p1 to p2 following the shortest path (a Great Circle). Note that the bearing of travel changes continuously while going along a great circle. A route with constant bearing is a rhumb line (see bearingRhumb).
Usage
bearing(p1, p2)
Arguments
p1
longitude/latitude of point(s). Can be a vector of two numbers, a matrix of 2 columns (first one is longitude, second is latitude) or a SpatialPoints* object