haversine formula (miles/meters)

gistfile1.cs

            double miles = 3956d*2d*Math.Asin
                                           (Math.Sqrt
                                                (Math.Pow(Math.Sin
                                                              ((orig_lat - dest_lat)*Math.PI/180d/2d),
                                                          2
                                                     )
                                                 + Math.Cos(orig_lat*Math.PI/180d)
                                                 *Math.Cos(dest_lat*Math.PI/180d)
                                                 *Math.Pow(Math.Sin((orig_lon - dest_lon)*Math.PI/180d/2d), 2
                                                      )
                                                )
                                           );
            var distanceInMeters = miles*1609.344;