Mapping Toolbox

geod2aut

Convert from geodetic to authalic latitudes

Syntax

• lat = geod2aut(lat0)
  lat = geod2aut(lat0,geoid)
  lat = geod2aut(lat,units)
  lat = geod2aut(lat,geoid,units)
  

Background

Longitudes have the same meaning whether the Earth is treated as a sphere or as an ellipsoid. However, the definition of latitude in the case of an ellipsoid is more complicated. Geodetic, or geographic, latitudes on an ellipsoid can be transformed to latitudes on an auxiliary sphere with certain properties.

Geodetic latitude: (also called geographic latitude) the angle a normal line passing through a surface point makes with the plane of the Equator.

Authalic latitude: latitudes on an auxiliary sphere that is equal in area to the ellipsoid.

Description

lat = geod2aut(lat0) returns the geodetic latitudes provided in lat0 transformed to authalic latitudes, which are returned in lat.

lat = geod2aut(lat0,geoid) defines the elliptical model of the Earth, given by the geoid vector geoid, from which lat0 is transformed. The default geoid is the same as the default of almanac('earth','geoid'), the 1980 Geodetic Reference System ellipsoid.

lat = geod2aut(lat,geoid,units) defines the angle units of the inputs and outputs, where units is any valid angle units string. The default is 'degrees'.

Examples

• lat = geod2aut([0 45 90])
  lat =
           0   44.8717   90.0000
  

See Also

almanac	Planetary data
geod2cen aut2geod	Other auxiliary latitude functions

gcxsc

geod2cen