Get the two points where two great cricles cross each other. Great circles are defined by two points on it.
Usage
gcIntersect(p1, p2, p3, p4)
Value
two points for each pair of great circles
Arguments
p1
Longitude/latitude of a single point, in degrees; 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
p3
As above
p4
As above
Author
Robert Hijmans, based on equations by Ed Williams (see reference)