/// <summary>
/// Calculates the distance from the source to destination location (in meters).
/// </summary>
/// <param name="src">The source location.</param>
/// <param name="dest">The destination location.</param>
/// <param name="radiusofearth">The radius of the earth in meters (default: 6371000).</param>
/// <returns>Returns the distance, in meters, from source to destination.</returns>
/// <remarks>
/// Note that we use the <a href="http://en.wikipedia.org/wiki/International_System_of_Units">International
/// System of Units (SI)</a>; units of distance are specified in meters. If you want to use imperial system (e.g.
/// miles, nautical miles, yards, foot and whathaveyou's) you need to convert from/to meters. You can use the
/// helper methods <see cref="MilesToMeters"/> / <see cref="MetersToMiles"/> and
/// <see cref="YardsToMeters"/> / <see cref="MetersToYards"/> for quick conversion.
/// </remarks>
internal static double DistanceTo(IGeoLocation src, IGeoLocation dest, double radiusofearth = RADIUSOFEARTH)
{
var dLat = GeoUtil.Deg2Rad(dest.Latitude - src.Latitude);
var dLon = GeoUtil.Deg2Rad(dest.Longitude - src.Longitude);
return(radiusofearth * (2 * Math.Asin(Math.Min(1, Math.Sqrt(Math.Sin(dLat / 2) * Math.Sin(dLat / 2) + Math.Cos(GeoUtil.Deg2Rad(src.Latitude)) * Math.Cos(GeoUtil.Deg2Rad(dest.Latitude)) * Math.Sin(dLon / 2) * Math.Sin(dLon / 2))))));
}
/// <summary>
/// Calculates a coordinate from a GeoName (latitude, longitude, altitude)
/// </summary>
/// <param name="n">The GeoName to determine the coordinate for.</param>
/// <param name="radiusofearth">Radius of the earth, in meters.</param>
/// <returns>Returns a coordinate (represented as an array of 3 doubles).</returns>
/// <remarks>This method is for internal use (for the KdTree) only.</remarks>
internal static double[] GetCoord(IGeoLocation n, double radiusofearth = RADIUSOFEARTH)
{
return(new[] {
radiusofearth *Math.Cos(GeoUtil.Deg2Rad(n.Latitude)) * Math.Cos(GeoUtil.Deg2Rad(n.Longitude)),
radiusofearth *Math.Cos(GeoUtil.Deg2Rad(n.Latitude)) * Math.Sin(GeoUtil.Deg2Rad(n.Longitude)),
radiusofearth *Math.Sin(GeoUtil.Deg2Rad(n.Latitude))
});
}