AsterixDisplayAnalyser.GeodeticCalculator.CalculateGeodeticCurve C# (CSharp) Метод

        public GeodeticCurve CalculateGeodeticCurve(Ellipsoid ellipsoid, GlobalCoordinates start, GlobalCoordinates end)
        {
            //
            // All equation numbers refer back to Vincenty's publication:
            // See http://www.ngs.noaa.gov/PUBS_LIB/inverse.pdf
            //

            // get constants
            double a = ellipsoid.SemiMajorAxis;
            double b = ellipsoid.SemiMinorAxis;
            double f = ellipsoid.Flattening;

            // get parameters as radians
            double phi1 = start.Latitude.Radians;
            double lambda1 = start.Longitude.Radians;
            double phi2 = end.Latitude.Radians;
            double lambda2 = end.Longitude.Radians;

            // calculations
            double a2 = a * a;
            double b2 = b * b;
            double a2b2b2 = (a2 - b2) / b2;

            double omega = lambda2 - lambda1;

            double tanphi1 = Math.Tan(phi1);
            double tanU1 = (1.0 - f) * tanphi1;
            double U1 = Math.Atan(tanU1);
            double sinU1 = Math.Sin(U1);
            double cosU1 = Math.Cos(U1);

            double tanphi2 = Math.Tan(phi2);
            double tanU2 = (1.0 - f) * tanphi2;
            double U2 = Math.Atan(tanU2);
            double sinU2 = Math.Sin(U2);
            double cosU2 = Math.Cos(U2);

            double sinU1sinU2 = sinU1 * sinU2;
            double cosU1sinU2 = cosU1 * sinU2;
            double sinU1cosU2 = sinU1 * cosU2;
            double cosU1cosU2 = cosU1 * cosU2;

            // eq. 13
            double lambda = omega;

            // intermediates we'll need to compute 's'
            double A = 0.0;
            double B = 0.0;
            double sigma = 0.0;
            double deltasigma = 0.0;
            double lambda0;
            bool converged = false;

            for (int i = 0; i < 20; i++)
            {
                lambda0 = lambda;

                double sinlambda = Math.Sin(lambda);
                double coslambda = Math.Cos(lambda);

                // eq. 14
                double sin2sigma = (cosU2 * sinlambda * cosU2 * sinlambda) + Math.Pow(cosU1sinU2 - sinU1cosU2 * coslambda, 2.0);
                double sinsigma = Math.Sqrt(sin2sigma);

                // eq. 15
                double cossigma = sinU1sinU2 + (cosU1cosU2 * coslambda);

                // eq. 16
                sigma = Math.Atan2(sinsigma, cossigma);

                // eq. 17    Careful!  sin2sigma might be almost 0!
                double sinalpha = (sin2sigma == 0) ? 0.0 : cosU1cosU2 * sinlambda / sinsigma;
                double alpha = Math.Asin(sinalpha);
                double cosalpha = Math.Cos(alpha);
                double cos2alpha = cosalpha * cosalpha;

                // eq. 18    Careful!  cos2alpha might be almost 0!
                double cos2sigmam = cos2alpha == 0.0 ? 0.0 : cossigma - 2 * sinU1sinU2 / cos2alpha;
                double u2 = cos2alpha * a2b2b2;

                double cos2sigmam2 = cos2sigmam * cos2sigmam;

                // eq. 3
                A = 1.0 + u2 / 16384 * (4096 + u2 * (-768 + u2 * (320 - 175 * u2)));

                // eq. 4
                B = u2 / 1024 * (256 + u2 * (-128 + u2 * (74 - 47 * u2)));

                // eq. 6
                deltasigma = B * sinsigma * (cos2sigmam + B / 4 * (cossigma * (-1 + 2 * cos2sigmam2) - B / 6 * cos2sigmam * (-3 + 4 * sin2sigma) * (-3 + 4 * cos2sigmam2)));

                // eq. 10
                double C = f / 16 * cos2alpha * (4 + f * (4 - 3 * cos2alpha));

                // eq. 11 (modified)
                lambda = omega + (1 - C) * f * sinalpha * (sigma + C * sinsigma * (cos2sigmam + C * cossigma * (-1 + 2 * cos2sigmam2)));

                // see how much improvement we got
                double change = Math.Abs((lambda - lambda0) / lambda);

                if ((i > 1) && (change < 0.0000000000001))
                {
                    converged = true;
                    break;
                }
            }

            // eq. 19
            double s = b * A * (sigma - deltasigma);
            Angle alpha1;
            Angle alpha2;

            // didn't converge?  must be N/S
            if (!converged)
            {
                if (phi1 > phi2)
                {
                    alpha1 = Angle.Angle180;
                    alpha2 = Angle.Zero;
                }
                else if (phi1 < phi2)
                {
                    alpha1 = Angle.Zero;
                    alpha2 = Angle.Angle180;
                }
                else
                {
                    alpha1 = new Angle(Double.NaN);
                    alpha2 = new Angle(Double.NaN);
                }
            }

            // else, it converged, so do the math
            else
            {
                double radians;
                alpha1 = new Angle();
                alpha2 = new Angle();

                // eq. 20
                radians = Math.Atan2(cosU2 * Math.Sin(lambda), (cosU1sinU2 - sinU1cosU2 * Math.Cos(lambda)));
                if (radians < 0.0) radians += TwoPi;
                alpha1.Radians = radians;

                // eq. 21
                radians = Math.Atan2(cosU1 * Math.Sin(lambda), (-sinU1cosU2 + cosU1sinU2 * Math.Cos(lambda))) + Math.PI;
                if (radians < 0.0) radians += TwoPi;
                alpha2.Radians = radians;
            }

            if (alpha1 >= 360.0) alpha1 -= 360.0;
            if (alpha2 >= 360.0) alpha2 -= 360.0;

            return new GeodeticCurve(s, alpha1, alpha2);
        }