R: Distance along a rhumb line

distRhumb {geosphere} | R Documentation

## Distance along a rhumb line

### Description

A rhumb line (loxodrome) is a path of constant bearing (direction), which crosses all meridians at the same angle.

### Usage

    distRhumb(p1, p2, r=6378137)

### 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
`r` | radius of the earth; default = 6378137 m

### Details

Rhumb (from the Spanish word for course, 'rumbo') lines are straight lines on a Mercator projection map. They were used in navigation because it is easier to follow a constant compass bearing than to continually adjust the bearing as is needed to follow a great circle, even though rhumb lines are normally longer than great-circle (orthodrome) routes. Most rhumb lines will gradually spiral towards one of the poles.

### Value

distance in units of r (default=meters)

### Author(s)

Robert Hijmans and Chris Veness

### References

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

### See Also

`distCosine, distHaversine, distVincentySphere, distVincentyEllipsoid`

### Examples

    distRhumb(c(10,10),c(20,20))

[Package geosphere version 1.5-5 Index]