.. _example_39:

(39) Evaluation of spherical harmonics coefficients
---------------------------------------------------

We use a spherical harmonic model for the topography of Venus and evaluate
the resulting global grid for three sets of upper order/degrees, here 30,
90, and 180; the original file (see below) goes to order and degree 720.
We use the coefficients to evaluate the grids and make perspective globes
of the different resolutions.  The key tool
used here is :doc:`sph2grd </sph2grd>`.

Note that we use a special format in :doc:`psscale </psscale>` so that the
annotations will include the separators for the thousands.

.. literalinclude:: /_verbatim/example_39.txt
   :language: bash

.. figure:: /_images/example_39.*
   :width: 500 px
   :align: center

   Evaluation of spherical harmonics coefficients.