[C#/COMMON] 거리 구하기

using System;

#region 거리 구하기 - GetDistance(startLatitude, startLongitude, endLatitude, endLongitude)

/// <summary>
/// 거리 구하기
/// </summary>
/// <param name="startLatitude">시작 위도</param>
/// <param name="startLongitude">시작 경도</param>
/// <param name="endLatitude">종료 위도</param>
/// <param name="endLongitude">종료 경도</param>
/// <returns>거리</returns>
public double GetDistance(double startLatitude, double startLongitude, double endLatitude, double endLongitude)
{
    double startLatitudeRadian  = startLatitude   * Math.PI / 180d;
    double startLongitudeRadian = startLongitude  * Math.PI / 180d;
    double endLatitudeRadian    = endLatitude     * Math.PI / 180d;
    double endLongitudeRadian   = endLongitude    * Math.PI / 180d;

    double distance = Math.Acos(Math.Sin(startLatitudeRadian) * Math.Sin(endLatitudeRadian) + 
        Math.Cos(startLatitudeRadian) * Math.Cos(endLatitudeRadian) * Math.Cos(endLongitudeRadian - startLongitudeRadian));

    return distance * 6371d; // 6371km : 지구 반지름?
}

#endregion