t   |
                  |                                |
                  |  dy/dlon   dy/dlat   dy/dalt   |
                  |                                |
                  |  dz/dlon   dz/dlat   dz/dalt   |
                   -                              -

               evaluated at the input values of 'lon', 'lat' and 'alt'.

</pre><h4><a name="Examples">Examples</a></h4><pre>

   None.

</pre><h4><a name="Particulars">Particulars</a></h4><pre>

   It is often convenient to describe the moti