earth.tri {fossil} | R Documentation |
Calculate the true area on a sphere enclosed by three points on the earth's surface
earth.tri(lat1, long1, lat2, long2, lat3, long3)
lat1 |
Latitude of site 1 |
long1 |
Longitude of site 1 |
lat2 |
Latitude of site 2 |
long2 |
Longitude of site 2 |
lat3 |
Latitude of site 3 |
long3 |
Longitude of site 3 |
A function to find the area enclosed by three points on the surface of the
earth, given their latitudes and longitudes. This function is primarily
designed to be a component of earth.poly
, which is likely a more
useful function for most applications.
Returns a value in kilometers squared of the area enclosed by the three points.
The distance calculated may be up to 0.2% inaccurate, as this function treats the Earth as a sphere with a circumference of 40003 km, rather than an ellipsoid like it actually is.
Matthew Vavrek
~put references to the literature/web site here ~
##add examples