Calculating Distance between two Latitude and Longitude GeoCoordinates

Question

I m calculating the distance between two GeoCoordinates  I m testing my app against 3-4 other apps  When I m calculating distance  I tend to get an average of 3 3 miles for my calculation whereas other apps are getting 3 5 miles  It s a big difference for the calculation I m trying to perform  Are there any good class libraries out there for calculating distance  I m calculating it like this in C    public static double Calculate double sLatitude double sLongitude  double eLatitude                                  double eLongitude        var radiansOverDegrees    Math PI   180 0        var sLatitudeRadians   sLatitude   radiansOverDegrees      var sLongitudeRadians   sLongitude   radiansOverDegrees      var eLatitudeRadians   eLatitude   radiansOverDegrees      var eLongitudeRadians   eLongitude   radiansOverDegrees       var dLongitude   eLongitudeRadians - sLongitudeRadians      var dLatitude   eLatitudeRadians - sLatitudeRadians       var result1   Math Pow Math Sin dLatitude   2 0   2 0                       Math Cos sLatitudeRadians    Math Cos eLatitudeRadians                       Math Pow Math Sin dLongitude   2 0   2 0           Using 3956 as the number of miles around the earth     var result2   3956 0   2 0                      Math Atan2 Math Sqrt result1   Math Sqrt 1 0 - result1         return result2      What could I be doing wrong  Should I calculate it in km first and then convert to miles

User · Answer

There s this library GeoCoordinate for these platforms    Mono  NET 4 5  NET Core Windows Phone 8 x Universal Windows Platform Xamarin iOS Xamarin Android   Installation is done via NuGet      PM  Install-Package GeoCoordinate   Usage  GeoCoordinate pin1   new GeoCoordinate lat  lng   GeoCoordinate pin2   new GeoCoordinate lat  lng    double distanceBetween   pin1 GetDistanceTo pin2     The distance between the two coordinates  in meters

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Try this       public double getDistance GeoCoordinate p1  GeoCoordinate p2                double d   p1 Latitude   0 017453292519943295          double num3   p1 Longitude   0 017453292519943295          double num4   p2 Latitude   0 017453292519943295          double num5   p2 Longitude   0 017453292519943295          double num6   num5 - num3          double num7   num4 - d          double num8   Math Pow Math Sin num7   2 0   2 0      Math Cos d    Math Cos num4     Math Pow Math Sin num6   2 0   2 0            double num9   2 0   Math Atan2 Math Sqrt num8   Math Sqrt 1 0 - num8            return  6376500 0   num9

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This is an old question  nevertheless the answers did not satisfy me regarding to performance and optimization    Here my optimized C  variant  distance in km  without variables and redundant calculations  very close to mathematical expression of Haversine Formular https   en wikipedia org wiki Haversine formula     Inspired by  https   rosettacode org wiki Haversine formula C 23  public static class Haversine       public static double Calculate double lat1  double lon1  double lat2  double lon2                double rad double angle    gt  angle   0 017453292519943295769236907684886127d       angle   Math Pi   180 0d         double havf double diff    gt  Math Pow Math Sin rad diff    2d   2        sin   diff   2          return 12745 6   Math Asin Math Sqrt havf lat2 - lat1    Math Cos rad lat1     Math Cos rad lat2     havf lon2 - lon1        earth radius 6 372 8 km x 2   12745 6

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The GeoCoordinate class   NET Framework 4 and higher  already has GetDistanceTo method   var sCoord   new GeoCoordinate sLatitude  sLongitude   var eCoord   new GeoCoordinate eLatitude  eLongitude    return sCoord GetDistanceTo eCoord     The distance is in meters   You need to reference System Device

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Calculating Distance between  Latitude and Longitude points             double Lat1   Convert ToDouble latitude           double Long1   Convert ToDouble longitude            double Lat2   30 678          double Long2   45 786          double circumference   40000 0     Earth s circumference at the equator in km         double distance   0 0          double latitude1Rad   DegreesToRadians Lat1           double latititude2Rad   DegreesToRadians Lat2           double longitude1Rad   DegreesToRadians Long1           double longitude2Rad   DegreesToRadians Long2           double logitudeDiff   Math Abs longitude1Rad - longitude2Rad           if  logitudeDiff  gt  Math PI                        logitudeDiff   2 0   Math PI - logitudeDiff                    double angleCalculation               Math Acos                Math Sin latititude2Rad    Math Sin latitude1Rad                  Math Cos latititude2Rad    Math Cos latitude1Rad    Math Cos logitudeDiff            distance   circumference   angleCalculation    2 0   Math PI           return distance

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You can use System device Location   System device Location GeoCoordinate gc   new System device Location GeoCoordinate    Latitude   yourLatitudePt1  Longitude   yourLongitudePt1     System device Location GeoCoordinate gc2   new System device Location GeoCoordinate    Latitude   yourLatitudePt2  Longitude   yourLongitudePt2     Double distance   gc2 getDistanceTo gc     good luck

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Here is the JavaScript version guys and gals  function distanceTo lat1  lon1  lat2  lon2  unit          var rlat1   Math PI   lat1 180       var rlat2   Math PI   lat2 180       var rlon1   Math PI   lon1 180       var rlon2   Math PI   lon2 180       var theta   lon1-lon2       var rtheta   Math PI   theta 180       var dist   Math sin rlat1    Math sin rlat2    Math cos rlat1    Math cos rlat2    Math cos rtheta         dist   Math acos dist        dist   dist   180 Math PI       dist   dist   60   1 1515       if  unit   K     dist   dist   1 609344         if  unit   N     dist   dist   0 8684         return dist

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For those who are using Xamarin and don t have access to the GeoCoordinate class  you can use the Android Location class instead   public static double GetDistanceBetweenCoordinates  double lat1  double lng1  double lat2  double lng2                var coords1   new Location                   coords1 Latitude   lat1              coords1 Longitude   lng1              var coords2   new Location                   coords2 Latitude   lat2              coords2 Longitude   lng2              return coords1 DistanceTo  coords2

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And here  for those still not satisfied  like me   the original code from  NET-Frameworks GeoCoordinate class  refactored into a standalone method  public double GetDistance double longitude  double latitude  double otherLongitude  double otherLatitude        var d1   latitude    Math PI   180 0       var num1   longitude    Math PI   180 0       var d2   otherLatitude    Math PI   180 0       var num2   otherLongitude    Math PI   180 0  - num1      var d3   Math Pow Math Sin  d2 - d1    2 0   2 0    Math Cos d1    Math Cos d2    Math Pow Math Sin num2   2 0   2 0            return 6376500 0    2 0   Math Atan2 Math Sqrt d3   Math Sqrt 1 0 - d3

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When CPU math computing power is limited   There are times  such as in my work  when computing power is scarce  e g  no floating point processor  working with small microcontrollers  where some trig functions can take an exorbitant amount of CPU time  e g  3000  clock cycles   so when I only need an approximation  especially if if the CPU must not be tied up for a long time  I use this to minimize CPU overhead      ------------------------------------------------------------------------     brief  Great Circle distance approximation in km over short distances        Can be off by as much as 10         approx distance in mi   sqrt x   x   y   y        where x   69 1    lat2 - lat1     and y   69 1    lon2 - lon1    cos lat1 57 3       ----------------------------------------------------------------------   double    ApproximateDisatanceBetweenTwoLatLonsInKm                    double lat1  double lon1                    double lat2  double lon2                           double  ldRadians  ldCosR  x  y       ldRadians    lat1   57 3    0 017453292519943295769236907684886      ldCosR   cos ldRadians       x   69 1    lat2 - lat1       y   69 1    lon2 - lon1    ldCosR       return sqrt x   x   y   y    1 609344      Converts mi to km         Credit goes to https   github com kristianmandrup geo vectors blob master Distance 20calc 20notes txt

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GetDistance is the best solution  but in many cases we can t use this Method  e g  Universal App    Pseudocode of the Algorithm to calculate the distance between to coorindates    public static double DistanceTo double lat1  double lon1  double lat2  double lon2  char unit    K         double rlat1   Math PI lat1 180      double rlat2   Math PI lat2 180      double theta   lon1 - lon2      double rtheta   Math PI theta 180      double dist           Math Sin rlat1  Math Sin rlat2    Math Cos rlat1           Math Cos rlat2  Math Cos rtheta       dist   Math Acos dist       dist   dist 180 Math PI      dist   dist 60 1 1515       switch  unit                case  K     Kilometers - gt  default             return dist 1 609344          case  N     Nautical Miles              return dist 0 8684          case  M     Miles             return dist             return dist     Real World C  Implementation  which makes use of an Extension Methods  Usage   var distance   new Coordinates 48 672309  15 695585                   DistanceTo                      new Coordinates 48 237867  16 389477                       UnitOfLength Kilometers                      Implementation   public class Coordinates       public double Latitude   get  private set        public double Longitude   get  private set         public Coordinates double latitude  double longitude                Latitude   latitude          Longitude   longitude          public static class CoordinatesDistanceExtensions       public static double DistanceTo this Coordinates baseCoordinates  Coordinates targetCoordinates                return DistanceTo baseCoordinates  targetCoordinates  UnitOfLength Kilometers              public static double DistanceTo this Coordinates baseCoordinates  Coordinates targetCoordinates  UnitOfLength unitOfLength                var baseRad   Math PI   baseCoordinates Latitude   180          var targetRad   Math PI   targetCoordinates Latitude  180          var theta   baseCoordinates Longitude - targetCoordinates Longitude          var thetaRad   Math PI   theta   180           double dist               Math Sin baseRad    Math Sin targetRad    Math Cos baseRad                Math Cos targetRad    Math Cos thetaRad           dist   Math Acos dist            dist   dist   180   Math PI          dist   dist   60   1 1515           return unitOfLength ConvertFromMiles dist            public class UnitOfLength       public static UnitOfLength Kilometers   new UnitOfLength 1 609344       public static UnitOfLength NauticalMiles   new UnitOfLength 0 8684       public static UnitOfLength Miles   new UnitOfLength 1        private readonly double  fromMilesFactor       private UnitOfLength double fromMilesFactor                 fromMilesFactor   fromMilesFactor             public double ConvertFromMiles double input                return input  fromMilesFactor

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You can use this function    Source   https   www geodatasource com developers c-sharp  private double distance double lat1  double lon1  double lat2  double lon2  char unit      if   lat1    lat2   amp  amp   lon1    lon2         return 0        else       double theta   lon1 - lon2      double dist   Math Sin deg2rad lat1     Math Sin deg2rad lat2     Math Cos deg2rad lat1     Math Cos deg2rad lat2     Math Cos deg2rad theta        dist   Math Acos dist       dist   rad2deg dist       dist   dist   60   1 1515      if  unit     K           dist   dist   1 609344        else if  unit     N           dist   dist   0 8684            return  dist                                                                                        This function converts decimal degrees to radians                                                                                         private double deg2rad double deg      return  deg   Math PI   180 0                                                                                    This function converts radians to decimal degrees                                                                                         private double rad2deg double rad      return  rad   Math PI   180 0      Console WriteLine distance 32 9697  -96 80322  29 46786  -98 53506   M     Console WriteLine distance 32 9697  -96 80322  29 46786  -98 53506   K     Console WriteLine distance 32 9697  -96 80322  29 46786  -98 53506   N

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Based on Elliot Wood s function  and if anyone is interested in a C function  this one is working      define SIM Degree to Radian x    float x   0 017453292F   define SIM PI VALUE                          3 14159265359   float GPS Distance float lat1  float lon1  float lat2  float lon2       float theta     float dist      theta   lon1 - lon2      lat1   SIM Degree to Radian lat1      lat2   SIM Degree to Radian lat2      theta   SIM Degree to Radian theta       dist    sin lat1    sin lat2      cos lat1    cos lat2    cos theta       dist   acos dist         dist   dist   180 0   SIM PI VALUE       dist   dist   60 0   1 1515          Convert to km         dist   dist   1 609344      dist    6370 693486F      return  dist       You may change it to double  It returns the value in km

[c#] Calculating Distance between two Latitude and Longitude GeoCoordinates

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