Package haversine is a Go library which implements the haversine formula. The haversine formula gives great-circle distances between two points on a sphere from their longitudes and latitudes. The sphere in this case is the surface of the Earth.

The dotted yellow line is an arc of a great circle. It gives the shortest distance between the two yellow points. Image courtesy USGS.

go get github.com/umahmood/haversine

cd $GOPATH/src/github.com/umahmood/haversine/

go test -v ./...

The below example shows how to calculate the shortest path between two coordinates on the surface of the Earth.

package main

import (
    "fmt"

    "github.com/umahmood/haversine"
)

func main() {
    oxford := haversine.Coord{Lat: 51.45, Lon: 1.15}  // Oxford, UK
    turin  := haversine.Coord{Lat: 45.04, Lon: 7.42}  // Turin, Italy
    mi, km := haversine.Distance(oxford, turin)
    fmt.Println("Miles:", mi, "Kilometers:", km)
}

http://godoc.org/github.com/umahmood/haversine

• https://plus.maths.org/content/lost-lovely-haversine
• https://en.wikipedia.org/wiki/Haversine_formula

See the LICENSE file for license rights and limitations (MIT).