R: Highest latitude on a great circle

gcMaxLat {geosphere} | R Documentation

## Highest latitude on a great circle

### Description

What is northern most point that will be reached when following a great circle? Computed with Clairaut's formula. The southern most point is the `antipode` of the northern-most point. This does not seem to be very precise; and you could use optimization instead to find this point (see examples)

### Usage

    gcMaxLat(p1, p2)

### 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

### Value

A matrix with coordinates (longitude/latitude)

### Author(s)

Ed Williams, Chris Veness, Robert Hijmans

### References

http://williams.best.vwh.net/ftp/avsig/avform.txt

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

### See Also

`gcLat, gcLon`

### Examples

    gcMaxLat(c(5,52), c(-120,37))

    # Another way to get there:
    f <- function(lon){gcLat(c(5,52), c(-120,37), lon)}
    optimize(f, interval=c(-180, 180), maximum=TRUE)

[Package geosphere version 1.5-5 Index]