List of all available named datums and reference ellipsoids:

Standard name of a datum in the Wolfram Language:

English name of a datum:

Alternate names:

List of available classes:

List of available named datums:

List of available reference ellipsoids:

List of direct datum transformations with available data:

Graph of those direct transformations:

List of available properties:

An ellipsoid of revolution is characterized by the semiaxes lengths {a,b} of a vertical section:

Or by the semimajor axis a and the inverse flattening :

The shape of an ellipse of semiaxes {a,b} can be described by the eccentricity :

The second eccentricity :

The flattening :

Or its inverse :

Specify an arbitrary oblate ellipsoid by giving the semiaxis lengths:

Specify the semimajor axis and the inverse flattening:

The Earth is nearly spherical:

Therefore, the various concepts of radius have similar values and are also similar to the semiaxes lengths:

With symbolic input:

On an ellipsoid, the curvature radius of a meridian varies with latitude, specified as a number in degrees:

Latitude can also be given as a Quantity angle:

Curvature radius of the normal section perpendicular to the meridian:

Curvature radius of a normal section of a given azimuth, measured clockwise from north:

Plot all possible values of the curvature radius of normal sections of the ellipsoid:

Convert from geodetic latitude to other types of latitude, and back to geodetic latitude:

Compute lengths along meridians. This is a quadrant (equator to pole):

Distance is not proportional to difference in geodetic latitude:

Each datum has an associated reference ellipsoid:

Different datums may have the same reference ellipsoid but differ in position or orientation:

Most properties of a datum are just properties of its ellipsoid:

The WGS 84 datum has been updated but the ellipsoid parameters have been kept:

A transformation between datums is represented as a pair:

The relation between two datums is encoded in the seven parameters of a Helmert transformation:

The relation between some datums changes in time. These are the parameters at definition time:

These are their variations per year: