The Haversine formula is used for calculating the distance between two points on the globe. This function gives a nearly accurate distance value, and is used widely in GPS related calculations and for vehicle tracking. This article provides a code snippet for calculating distance between two points taking latitude and longitude values as example.
This article is a sequel to the previous article on the same topic, but using T-SQL for calculation - Calculate distance between two points on globe from latitude and longitude coordinates. Please refer to this article for details of the Haversine formula and distance calculation.
The C# implementation of the Haversine formula is:
public double GetDistanceBetweenPoints(double lat1, double long1, double lat2, double long2)
{
double distance = 0;
double dLat = (lat2 - lat1) / 180* Math.PI;
double dLong = (long2 - long1) / 180 * Math.PI;
double a = Math.Sin(dLat / 2) * Math.Sin(dLat / 2)
+ Math.Cos(lat2) * Math.Sin(dLong/2) * Math.Sin(dLong/2);
double c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
//Calculate radius of earth
// For this you can assume any of the two points.
double radiusE = 6378135; // Equatorial radius, in metres
double radiusP = 6356750; // Polar Radius
//Numerator part of function
double nr = Math.Pow(radiusE * radiusP * Math.Cos(lat1 / 180 * Math.PI), 2);
//Denominator part of the function
double dr = Math.Pow(radiusE * Math.Cos(lat1 / 180 * Math.PI), 2)
+ Math.Pow(radiusP * Math.Sin(lat1 / 180 * Math.PI), 2);
double radius = Math.Sqrt(nr / dr);
//Calaculate distance in metres.
distance = radius * c;
return distance;
}
The datatype used for all variables is double. The latitude and longitude values also expressed as double typed, so it requires conversion of the original coordinate value in degrees into double datatypes.
Double value = degree + minute / 60 + seconds / 3600
