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Last data update: 2014.03.03

R: Intersections of two great circles

gcIntersectBearing

R Documentation

Intersections of two great circles

Description

Get the two points where two great cricles cross each other. In this function, great circles are defined by a points and an initial bearing. In function gcIntersect they are defined by two sets of points.

Usage

gcIntersectBearing(p1, brng1, p2, brng2)

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
`brng1`	Bearing from p1
`p2`	As above. Should have same length as p1, or a single point (or vice versa when p1 is a single point
`brng2`	Bearing from p2

Value

a matrix with four columns (two points)

Author(s)

Chris Veness and Robert Hijmans based on code by Ed Williams

References

http://williams.best.vwh.net/avform.htm#Intersection

http://www.movable-type.co.uk/scripts/latlong.html

Examples

gcIntersectBearing(c(10,0), 10, c(-10,0), 10)