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geosphere (version 1.5-20)

antipode: Antipodes

Description

Compute an antipode, or check whether two points are antipodes. Antipodes are places on Earth that are diametrically opposite to one another; and could be connected by a straight line through the centre of the Earth.

Antipodal points are connected by an infinite number of great circles (e.g. the meridians connecting the poles), and can therefore not be used in some great circle based computations.

Usage

antipode(p)
antipodal(p1, p2, tol=1e-9)

Value

antipodal points or a logical value (TRUE if antipodal)

Arguments

p

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

p1

as above

p2

as above

tol

tolerance for equality

Author

Robert Hijmans

References

https://en.wikipedia.org/wiki/Antipodes

Examples

Run this code
antipode(rbind(c(5,52), c(-120,37), c(-60,0), c(0,70)))
antipodal(c(0,0), c(180,0))

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