R: Intersections of two great circles

gcIntersect {geosphere} | R Documentation

## Intersections of two great circles

### Description

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)

### 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

### Value

two points for each pair of great circles

### Author(s)

Robert Hijmans, based on equations by Ed Williams (see reference)

### References

http://williams.best.vwh.net/intersect.htm

### See Also

`gcIntersectBearing`

### Examples

    p1 <- c(5,52); p2 <- c(-120,37); p3 <- c(-60,0); p4 <- c(0,70)
    gcIntersect(p1,p2,p3,p4)

[Package geosphere version 1.5-5 Index]