//******************************************************************************************************//  GeoCoordinate.cs - Gbtc////  Copyright © 2016, Grid Protection Alliance.  All Rights Reserved.////  Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See//  the NOTICE file distributed with this work for additional information regarding copyright ownership.//  The GPA licenses this file to you under the MIT License (MIT), the "License"; you may//  not use this file except in compliance with the License. You may obtain a copy of the License at:////      http://opensource.org/licenses/MIT////  Unless agreed to in writing, the subject software distributed under the License is distributed on an//  "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the//  License for the specific language governing permissions and limitations.////  Code Modification History://  ----------------------------------------------------------------------------------------------------//  08/20/2016 - Stephen C. Wills//       Generated original version of source code.////****************************************************************************************************** using System; namespace GSF.Geo{    /// <summary>    /// Represents a location in the geographical coordinate system.    /// </summary>    public class GeoCoordinate    {        #region [ Constructors ]         /// <summary>        /// Creates a new instance of the <see cref="GeoCoordinate"/> class.        /// </summary>        /// <param name="latitude">The latitude of the geographical coordinate.</param>        /// <param name="longitude">The longitude of the geographical coordinate.</param>        public GeoCoordinate(double latitude, double longitude)        {            Latitude = latitude;            Longitude = longitude;        }         #endregion         #region [ Properties ]         /// <summary>        /// Gets the latitude of the geographical coordinate.        /// </summary>        public double Latitude        {            get;            private set;        }         /// <summary>        /// Gets the longitude of the geographical coordinate.        /// </summary>        public double Longitude        {            get;            private set;        }         #endregion         #region [ Methods ]         /// <summary>        /// Calculates distance between this and another <see cref="GeoCoordinate"/> value.        /// </summary>        /// <param name="other">Other <see cref="GeoCoordinate"/>.</param>        /// <returns>Distance between two <see cref="GeoCoordinate"/> values.</returns>        public double Distance(GeoCoordinate other)        {            const double RadianConversionFactor = Math.PI / 180.0D;             double r = 6378137;            double lambda1 = Longitude * RadianConversionFactor;            double lambda2 = other.Longitude * RadianConversionFactor;            double phi1 = Latitude * RadianConversionFactor;            double phi2 = other.Latitude * RadianConversionFactor;            double dPhi = phi2 - phi1;            double dLambda = lambda2 - lambda1;             double a = Math.Sin(dPhi / 2) * Math.Sin(dPhi / 2) +                    Math.Cos(phi1) * Math.Cos(phi2) *                    Math.Sin(dLambda / 2) * Math.Sin(dLambda / 2);             double c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));             return r * c;        }         #endregion    }}