using System;

​

public struct GeoCoordinate {

    public double Lat;

    public double Lon;

​

    public GeoCoordinate(double lat, double lon){

        Lat = lat;

        Lon = lon;

    }

    public override string ToString() {

        return $"Latitude: {Lat}, Longitude: {Lon}";

    }

}

public class Program

{   

    public static void Main()

    {

        GeoCoordinate p1 = new GeoCoordinate(60.188865200000000000000000000, 24.905851100000000000000000000);

        GeoCoordinate p2 = new GeoCoordinate(61.0813404016871, 25.0358895057222);

        double dist = p1.CalculateDistance(p2);

        Console.WriteLine($"Distance: {dist}");

    }

}

​

public static class GExtensions {

    public static double CalculateDistance(this GeoCoordinate startingCoordinate, GeoCoordinate toCoordinate)

    {

        Console.WriteLine($"startingCoordinate: {startingCoordinate}");

        Console.WriteLine($"toCoordinate: {toCoordinate}");

        Console.WriteLine();

​

        // In meters

        const int earthMeanRadius = 6378137;

        const double radiansToDegrees = Math.PI / 180;

        Console.WriteLine($"Radians to degrees: {radiansToDegrees}");

        Console.WriteLine();

​

        Console.WriteLine($"Delta latitude: {toCoordinate.Lat - startingCoordinate.Lat}");

        Console.WriteLine($"Delta longitude: {toCoordinate.Lon - startingCoordinate.Lon}");

Console.WriteLine();

​

        // Calculate coordinate difference and convert to degrees

        var deltaLatitude = (double)(toCoordinate.Lat - startingCoordinate.Lat) * radiansToDegrees;

        var deltaLongitude = (double)(toCoordinate.Lon - startingCoordinate.Lon) * radiansToDegrees;

​

        Console.WriteLine($"deltaLatitude to degrees: {deltaLatitude}");

        Console.WriteLine($"deltaLongitude to degrees: {deltaLongitude}");

        Console.WriteLine();

​

        // Latitudes to degrees

        var startLatitudeDegrees = (double) startingCoordinate.Lat * radiansToDegrees;

        var toLatitudeDegrees = (double) toCoordinate.Lat * radiansToDegrees;

​

        Console.WriteLine($"startLatitudeDegrees: {startLatitudeDegrees}");

        Console.WriteLine($"toLatitudeDegrees: {toLatitudeDegrees}");

        Console.WriteLine();    

        var distanceLatitudeCosine = Math.Cos(startLatitudeDegrees) * Math.Cos(toLatitudeDegrees);

        Console.WriteLine($"distanceLatitudeCosine: {distanceLatitudeCosine}");

        Console.WriteLine();    

​

        // Calculate haversine

        var haversineLatitude = Math.Pow(Math.Sin(deltaLatitude / 2), 2);

        var haversineLongitude = Math.Pow(Math.Sin(deltaLongitude / 2), 2);

​

        Console.WriteLine($"haversineLatitude: {(decimal)haversineLatitude}");

        Console.WriteLine($"haversineLongitude: {(decimal)haversineLongitude}");

        Console.WriteLine();    

​

        // Apply formulae

        var appliedFormulae = haversineLatitude + distanceLatitudeCosine * haversineLongitude;

​

        Console.WriteLine($"appliedFormulae: {(decimal)appliedFormulae}");

        Console.WriteLine();    

​

        var c = 2 * Math.Atan2(Math.Sqrt(appliedFormulae), Math.Sqrt(1 - appliedFormulae));

​

        Console.WriteLine($"c: {c}");

        Console.WriteLine();    

​

        var distanceInMeters = earthMeanRadius * c;

​

        Console.WriteLine($"distanceInMeters: {distanceInMeters} meters");

        Console.WriteLine();    

        // Return in kilometers

        return distanceInMeters / 1000;

    }

}