R: Direction of travel

bearing {geosphere} | R Documentation

## Direction of travel

### Description

Get the initial bearing (direction; azimuth) to go from point `p1` to point `p2` (in longitude/latitude) following the shortest path on an ellipsoid (geodetic). Note that the bearing of travel changes continuously while going along the path. A route with constant bearing is a rhumb line (see `bearingRhumb`).

### Usage

    bearing(p1, p2, a=6378137, f=1/298.257223563)

### 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
`p2` | as above
`a` | major (equatorial) radius of the ellipsoid. The default value is for WGS84
`f` | ellipsoid flattening. The default value is for WGS84

### Value

Bearing in degrees

### Note

use `f=0` to get a bearing on a sphere (great circle)

### Author(s)

Robert Hijmans

### References

C.F.F. Karney, 2013. Algorithms for geodesics, J. Geodesy 87: 43-55. https://dx.doi.org/10.1007/s00190-012-0578-z. Addenda: http://geographiclib.sf.net/geod-addenda.html. Also see http://geographiclib.sourceforge.net/

### See Also

`bearingRhumb`

### Examples

    bearing(c(10,10),c(20,20))

[Package geosphere version 1.5-5 Index]