public class Logic{    private static readonly double eps = 1e-10;    public static Point FindFermat(List<Point> poly, double step = 10)    {        if (poly == null || poly.Count == 0) return null;        if (poly.Count == 1) return poly[0];        if (poly.Count == 2) return new Point() { x = (poly[0].x + poly[1].x) / 2, y = (poly[0].y + poly[1].y) / 2 };        Point basePoint = new Point() { x = poly[0].x, y = poly[0].y };        double ans = AllDistance(poly[0].x, poly[0].y, poly);        double a = poly[0].x, b = poly[0].y;        double ta = a, tb = b, temp = 0;        while (step > eps)        {            bool flag = true;            while (flag)            {                flag = false;                temp = AllDistance(a + step, b, poly);                if (temp < ans)                {                    flag = true;                    ans = temp;                    ta = a + step;                    tb = b;                }                temp = AllDistance(a - step, b, poly);                if (temp < ans)                {                    flag = true;                    ans = temp;                    ta = a - step;                    tb = b;                }                temp = AllDistance(a, b + step, poly);                if (temp < ans)                {                    flag = true;                    ans = temp;                    ta = a;                    tb = b + step;                }                temp = AllDistance(a, b - step, poly);                if (temp < ans)                {                    flag = true;                    ans = temp;                    ta = a;                    tb = b - step;                }                a = ta;                b = tb;            }            step *= 0.5;        }        return new Point() { x = a, y = b };    }    private Point Move(Point p, Point direct)    {        return new Point()        {            x = p.x + direct.x,            y = p.y + direct.y        };    }    private static double AllDistance(double tx, double ty, List<Point> pList)    {        double ans = 0;        foreach (var point in pList)        {            ans += Distance(new Point() { x = tx, y = ty }, point);        }        return ans;    }    private static double Distance(Point a, Point b)    {        return Math.Sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));    }    private const double EARTH_RADIUS = 6378.137;    private static double rad(double d)    {        return d * Math.PI / 180.0;    }    /// <summary>    /// 点到点间的距离    /// </summary>    /// <param name="lat1"></param>    /// <param name="lng1"></param>    /// <param name="lat2"></param>    /// <param name="lng2"></param>    /// <returns></returns>    public static double GetDistance(double lat1, double lng1, double lat2, double lng2)    {        double radLat1 = rad(lat1);        double radLat2 = rad(lat2);        double a = radLat1 - radLat2;        double b = rad(lng1) - rad(lng2);        double s = 2 * Math.Asin(Math.Sqrt(Math.Pow(Math.Sin(a / 2), 2) +         Math.Cos(radLat1) * Math.Cos(radLat2) * Math.Pow(Math.Sin(b / 2), 2)));        s = s * EARTH_RADIUS;        s = Math.Round(s * 10000) / 10000;        return s;    }}