double  a = 6378137; // большая полуось в метрах
             double degreeSz;
             string s;
             if (wgs84) {
               double pCompression = 1.0/ 298.257223563;// полярное сжатие  гост
               double b = a * (1 - pCompression);
               s = String.Format("{0:0.0000}",b);
               l.WriteLine("polar axis/Equatorial: {0}/{1} meters", s, a);
               double sa = a*a;
               double seccentricity =  (sa - b*b) / sa ;
               double eccentricity = Math.Sqrt ( seccentricity );
               l.WriteLine("eccentricity: {0}/{1} ", eccentricity, "0.0818191908426");
               double sinB = sin(ltt);
               double N =   a / ( Math.Sqrt (1- seccentricity * sinB*sinB));
               double r =    (cos(ltt) * N );  //  радиус эллипса серапинас стр11.
//"Серапинас Б.Б_Математическая картография_Учебник для ВУЗов_М_ИЦ Академия_2005.pdf" 
               degreeSz =  ( r * Math.PI ) / 180.0; // длина градуса на эллипесе WGS84
               s = String.Format("{0:0.00}",degreeSz);
               double dltt  = ltt; 
               l.WriteLine("length of 1 degree with  {0:0.00} degree of latitude is {1:0.00} meters (WGS84)"
                 , dltt, s);

               l.WriteLine("length of 1 degree with  50.45 degree of latitude (Kiev) is {1:0.00} meters (WGS84)"
                 , (double)ltt, 571148.345319575 - 500124.473065682);


             }
             else {
                degreeSz =  (cos(ltt)* a * Math.PI ) / 180.0;
                s = String.Format("{0:0.00}",degreeSz);
                l.WriteLine("length of 1 degree with  {0:0.00} degree of latitude is {1:0.00} meters (Web Mercator)"
                 , (double)ltt, s);
             }
             Console.WriteLine(s);