geodist

A Go package for computing the distance between two geographic coordinates using the Haversine or Vincenty formula.

Installation

go get github.com/jftuga/geodist

Algorithm Comparison

• Vincenty is more accurate than Haversine because it considers the Earth's ellipticity when performing the calculation, but takes a longer time to compute.
• Wikipedia: Haversine
• Wikipedia: Vincenty
• Is the Haversine Formula or the Vincenty's Formula better for calculating distance?

Both functions return distances in miles and kilometers, in that order. Coordinates are in degrees, with latitude in [-90, 90] and any finite longitude (normalized modulo 360). West longitudes and south latitudes are negative.

VincentyDistance returns -1, -1, error for invalid coordinates or failure to converge. Some nearly antipodal points do not converge. HaversineDistance returns NaN, NaN for invalid coordinates; it uses a sphere with a radius of 6,378,100 meters.

Example

The following complete program is also available in example/example.go.

package main

import (
	"fmt"

	"github.com/jftuga/geodist"
)

func main() {
	var newYork = geodist.Coord{Lat: 40.7128, Lon: -74.0060}
	var sanDiego = geodist.Coord{Lat: 32.7157, Lon: -117.1611}
	miles, km, err := geodist.VincentyDistance(newYork, sanDiego)
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Printf(" [Vincenty] New York to San Diego: %.3f mi, %.3f km\n", miles, km)
	miles, km = geodist.HaversineDistance(newYork, sanDiego)
	fmt.Printf("[Haversine] New York to San Diego: %.3f mi, %.3f km\n", miles, km)

	fmt.Println()

	var elPaso = geodist.Coord{Lat: 31.7619, Lon: -106.4850}
	var stLouis = geodist.Coord{Lat: 38.6270, Lon: -90.1994}
	miles, km, err = geodist.VincentyDistance(elPaso, stLouis)
	if err != nil {
		fmt.Println(err)
		return
	}
	fmt.Printf(" [Vincenty] El Paso to St. Louis: %.3f mi, %.3f km\n", miles, km)
	miles, km = geodist.HaversineDistance(elPaso, stLouis)
	fmt.Printf("[Haversine] El Paso to St. Louis: %.3f mi, %.3f km\n", miles, km)
}

Run it from the repository root:

go run ./example

Output:

 [Vincenty] New York to San Diego: 2432.880 mi, 3915.341 km
[Haversine] New York to San Diego: 2430.504 mi, 3911.517 km

 [Vincenty] El Paso to St. Louis: 1033.858 mi, 1663.833 km
[Haversine] El Paso to St. Louis: 1033.678 mi, 1663.543 km

Online Calculators

• Great Circle: NOAA: Latitude/Longitude Distance Calculator
• Haversine: Movable Type: Calculate distance, bearing and more between Latitude/Longitude points
• Vincenty: Mike Turnbull (formerly CQSRG): WGS-84 World Geodetic System Distance Calculator

When comparing results, check the calculator's units and Earth model. Spherical calculators may use a different Earth radius from this package.

Acknowledgements

• Haversine implementation in Go by Conner DiPaolo.
• Vincenty implementation in JavaScript by Chris Veness; archived version used for the original port.