R: Longitude on a Great Circle

gcLon {geosphere} | R Documentation

## Longitude on a Great Circle

### Description

Longitudes at which a great circle crosses a latitude (parallel)

### Usage

    gcLon(p1, p2, lat)

### 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
`p2` | as above
`lat` | a latitude

### Value

vector of two numbers (longitudes)

### Author(s)

Robert Hijmans based on code by Ed Williams

### References

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

### See Also

`gcLat, gcMaxLat`

### Examples

    gcLon(c(5,52), c(-120,37), 40)

[Package geosphere version 1.5-5 Index]