ArcGIS上根据经纬度求地球表面两点间距离的实现

以米为单位。.Net2.0，C#实现。
       public static double DistanceOfTwoPoints(double lng1,double lat1, double lng2, double lat2, GaussSphere gs)
        {           
            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)));

字串3
            s = s * (gs == GaussSphere.WGS84 ? 6378137.0 : (gs == GaussSphere.Xian80 ? 6378140.0 : 6378245.0));
            s = Math.Round(s * 10000) / 10000;
            return s;
        }
       
        private static double Rad(double d)
        {
            return d * Math.PI / 180.0;
        } 字串9

GaussSphere 为自定义枚举类型
    /// <summary>
    /// 高斯投影中所选用的参考椭球
    /// </summary>
    public enum GaussSphere
    {
        Beijing54,
        Xian80,
        WGS84,
    }

from: http://hi.baidu.com/bell9527/item/732ac2fe7db97eec1b111f9d