geodist

README

geodist

GoLang package to compute the distance between two geographic latitude, longitude coordinates

Algorithm Comparison

• Vincenty is more accurate than Haversine because is 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?

Example

• example.go

	var newYork = geodist.Coord{Lat: 40.7128, Lon: 74.0060}
	var sanDiego = geodist.Coord{Lat: 32.7157, Lon: 117.1611}
	miles, km, ok := geodist.VincentyDistance(newYork, sanDiego)
	if !ok {
		fmt.Println("Unable to compute Vincenty Distance.")
		return
	}
	fmt.Printf(" [Vincenty] New York to San Diego: %.3f m, %.3f km\n", miles, km)

	var elPaso = geodist.Coord{Lat: 31.7619, Lon: 106.4850}
	var stLouis = geodist.Coord{Lat: 38.6270, Lon: 90.1994}
	miles, km = geodist.HaversineDistance(elPaso, stLouis)
	fmt.Printf("[Haversine] El Paso to St. Louis:  %.3f m, %.3f km\n", miles, km)

Online Calculators

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

Acknowledgements

• Haversine Algorithm in GoLang
• Vincenty Algorithm in JavaScript

Documentation

Index

• func HaversineDistance(p1, p2 Coord) (float64, float64)
• func VincentyDistance(p1, p2 Coord) (float64, float64, error)
• type Coord

Functions

func HaversineDistance

func HaversineDistance(p1, p2 Coord) (float64, float64)

HaversineDistance returns the distance (in miles) between two points of

a given longitude and latitude relatively accurately (using a spherical
approximation of the Earth) through the Haversin Distance Formula for
great arc distance on a sphere with accuracy for small distances

point coordinates are supplied in degrees and converted into rad. in the func

http://en.wikipedia.org/wiki/Haversine_formula

func VincentyDistance

func VincentyDistance(p1, p2 Coord) (float64, float64, error)

VincentyDistance computes the distances between two georgaphic coordinates

Args:

p1: the 'starting' point, given in latitude, longitude as a Coord struct

p2: the 'ending' point

Returns:

A 3 element tuple: distance between the 2 points given in (1) miles and (2) kilometers
The 3rd element will return true upon a successful computation or
false if the algorithm fails to converge. -1, -1, false is returned upon failure

Types

type Coord

type Coord struct {
	Lat float64
	Lon float64
}

Coord represents a geographic coordinate