# Haversine Distance

Calculates the distance on a sphere between two points given in latitude and longitude using the haversine formula.

The haversine formula can be found on Wikipedia

The Haversine Distance is implemented as a function as a class would be kind of overkill.

`haversineDinstance(la1: Double, lo1: Double, la2: Double, lo2: Double, radius: Double = 6367444.7) -> Double`

`la1`

is the latitude of point 1 in degrees.`lo1`

is the longitude of point 1 in degrees.`la2`

is the latitude of point 2 in degrees.`lo2`

is the longitude of point 2 in degrees.`radius`

is the radius of the sphere considered in meters, which defaults to the mean radius of the earth (from WolframAlpha).

The function contains 3 closures in order to make the code more readable and comparable to the Haversine formula given by the Wikipedia page mentioned above.

`haversine`

implements the haversine, a trigonometric function.`ahaversine`

the inverse function of the haversine.`dToR`

a closure converting degrees to radians.

The result of `haversineDistance`

is returned in meters.

*Written for Swift Algorithm Club by Jaap Wijnen.*