distGeo
Distance on an ellipsoid (the geodesic)
Highly accurate estimate of the shortest distance between two points on an ellipsoid (default is WGS84 ellipsoid). The shortest path between two points on an ellipsoid is called the geodesic.
 Keywords
 spatial
Usage
distGeo(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 column is longitude, second column is latitude) or a SpatialPoints* object
 p2
as above; or missing, in which case the sequential distance between the points in p1 is computed
 a
numeric. Major (equatorial) radius of the ellipsoid. The default value is for WGS84
 f
numeric. Ellipsoid flattening. The default value is for WGS84
Details
Parameters from the WGS84 ellipsoid are used by default. It is the best available global ellipsoid, but for some areas other ellipsoids could be preferable, or even necessary if you work with a printed map that refers to that ellipsoid. Here are parameters for some commonly used ellipsoids. Also see the refEllipsoids
function.
ellipsoid 
a 
f 

WGS84 
6378137 
1/298.257223563 

GRS80 
6378137 
1/298.257222101 

GRS67 
6378160 
1/298.25 

Airy 1830 
6377563.396 
1/299.3249646 

Bessel 1841 
6377397.155 
1/299.1528434 

Clarke 1880 
6378249.145 
1/293.465 

Clarke 1866 
6378206.4 
1/294.9786982 

International 1924 
6378388 
1/297 

Krasovsky 1940 
6378245 
1/298.2997381 
Value
Vector of distances in meters
References
C.F.F. Karney, 2013. Algorithms for geodesics, J. Geodesy 87: 4355. https://dx.doi.org/10.1007/s001900120578z. Addenda: http://geographiclib.sf.net/geodaddenda.html. Also see http://geographiclib.sourceforge.net/
See Also
distCosine, distHaversine, distVincentySphere, distVincentyEllipsoid, distMeeus
Examples
# NOT RUN {
distGeo(c(0,0),c(90,90))
# }