## Syntax

`az = azimuth(lat1,lon1,lat2,lon2)`

az = azimuth(lat1,lon1,lat2,lon2,ellipsoid)

az = azimuth(lat1,lon1,lat2,lon2,`units`

)

az = azimuth(lat1,lon1,lat2,lon2,ellipsoid,`units`

)

az = azimuth(`track`

,...)

## Description

`az = azimuth(lat1,lon1,lat2,lon2)`

calculates
the great circle azimuth from point 1 to point 2, for pairs of points
on the surface of a sphere. The input latitudes and longitudes can
be scalars or arrays of matching size. If you use a combination of
scalar and array inputs, the scalar inputs will be automatically expanded
to match the size of the arrays. The function measures azimuths clockwise
from north and expresses them in degrees or radians.

`az = azimuth(lat1,lon1,lat2,lon2,ellipsoid)`

computes
the azimuth assuming that the points lie on the ellipsoid defined
by the input `ellipsoid`

. `ellipsoid`

is
a `referenceSphere`

, `referenceEllipsoid`

, or `oblateSpheroid`

object, or a vector
of the form `[semimajor_axis eccentricity]`

. The
default ellipsoid is a unit sphere.

`az = azimuth(lat1,lon1,lat2,lon2,``units`

)

uses
the input string `units`

to define the angle
units of `az`

and the latitude-longitude coordinates.
Use `'degrees'`

(the default value), in the range
from 0 to 360, or `'radians'`

, in the range from
0 to 2*pi.

`az = azimuth(lat1,lon1,lat2,lon2,ellipsoid,``units`

)

specifies
both the `ellipsoid`

vector and the units of `az`

.

`az = azimuth(``track`

,...)

uses
the input string `track`

to specify either
a great circle or a rhumb line azimuth calculation. Enter `'gc'`

for
the `track`

string (the default value), to
obtain great circle azimuths for a sphere or geodesic azimuths for
an ellipsoid. (Hint to remember string name: the letters "g"
and "c" are in both great circle and geodesic.) Enter `'rh'`

for
the `track`

string to obtain rhumb line azimuths
for either a sphere or an ellipsoid.

## Examples

Find the azimuth between two points on the same parallel, for
example, (10ºN, 10ºE) and (10ºN, 40ºE). The azimuth
between two points depends on the `track`

string
selected.

% Try the 'gc' track string.
az = azimuth('gc',10,10,10,40)
% Compare to the result obtained from the 'rh' track string.
az = azimuth('rh',10,10,10,40)

Find the azimuth between two points on the same meridian, say
(10ºN, 10ºE) and (40ºN, 10ºE):

% Try the 'gc' track string.
az = azimuth(10,10,40,10)
% Compare to the 'rh' track string.
az = azimuth('rh',10,10,40,10)

Rhumb lines and great circles coincide along meridians and the
Equator. The azimuths are the same because the paths coincide.