fArcDistance

Function to calculate the great circle distance, forward and backward azimuths between two geographic points on a spherical earth.

Function to calculate the great circle distance and azimuth between two geographic points on a spherical earth.

In surveying science, the azimuth is also known as 'bearing'. It is measured clockwise from the north.

There are the fore bearing and back bearing; the difference between them is 180 degrees. They are opposite to each other.

This function is useful when you do not have access to MATLAB's Mapping Toolbox.

Inputs:

Lon1 is the longitude of the first point; specified in decimal degrees.

Lon2 is the longitude of the second point; specified in decimal degrees.

Lat1 is the latitude of the first point; specified in decimal degrees.

Lat2 is the latitude of the second point; specified in decimal degrees.

DistanceUnit ::optional:: is the unit to express the computed distance in; specified as a string. Default is "km".

Outputs:

Distance is the great circle distance between the two geographic points. Unit is given by DistanceUnit; default is km.

ForeAzimuth is the direction (bearing) from the first point to the second point using the north as reference. Unit is degree or radian; default is degree.

BackAzimuth is the direction (bearing) from the second point to the first point using the north as reference. Unit is degree or radian; default is degree.

Usage example:

Lon1 = -10.167293 * ones(10,1);
Lon2 = -109.089123 * ones(10,1);
Lat1 = -59.810366 * ones(10,1);
Lat2 = 71.1873231 * ones(10,1);
[Distance, ForeAzimuth, BackAzimuth] = fArcDistance(Lon1, Lon2, Lat1, Lat2);                 % Distance in kilometres, Azimuth in degrees
[Distance, ForeAzimuth, BackAzimuth] = fArcDistance(Lon1, Lon2, Lat1, Lat2, "m");            % Distance in metres, Azimuth in degrees
[Distance, ForeAzimuth, BackAzimuth] = fArcDistance(Lon1, Lon2, Lat1, Lat2, "km");           % Distance in kilometres, Azimuth in degrees
[Distance, ForeAzimuth, BackAzimuth] = fArcDistance(Lon1, Lon2, Lat1, Lat2, "deg");          % Distance in degrees, Azimuth in degrees
[Distance, ForeAzimuth, BackAzimuth] = fArcDistance(Lon1, Lon2, Lat1, Lat2, "rad");          % Distance in radians, Azimuth in radians
[Distance, ForeAzimuth, BackAzimuth] = fArcDistance(Lon1, Lon2, Lat1, Lat2, "mile");         % Distance in statute miles, Azimuth in degrees
[Distance, ForeAzimuth, BackAzimuth] = fArcDistance(Lon1, Lon2, Lat1, Lat2, "nautical");     % Distance in nautical miles, Azimuth in degrees