Usage
=====

WIP

Magnetic Models
---------------

- how to load and evaluate magnetic models
- generic model interface
- core and lithospheric models
- magnetospheric models
- ionospheric models
- combined and composed models
- field line tracing

Coordinate Conversions
----------------------
- magnetic coordinates
    - Quasi-Dipole coordinates (with and without the base vectors)
    - Magnetic Local Time
    - dipole coordinates
    - magnetic universal time
- geographic coordinates
    - spherical coordinates
    - Cartesian coordinates
    - geodetic (WGS84) coordinates
- vector rotations between different coordinate frames

Time Conversions
----------------
- MJD2000 <=> decimal year
- MDD2000 => year fraction

Sun Positions
-------------

- ``sunpos``

Utilities
---------

- vector operations

Low Level Spherical Harmonics
-----------------------------
- ``legendre``
- ``loncossin``
- ``relradpow``
- ``sheval``
- ``sheval_dipole``
- ``sphargrd``
- ``spharpot``