tor,
called <a href="index.html#showmotion">showmotion</a>, that uses Matlab's
handle graphics to display animations directly, thereby eliminating the
dependence on an external graphics program.&nbsp; There have also been several
changes to the format of drawing instructions.
</p>

<p>
Three more changes worth noting are that (1) non-default gravity must now be
specified as a field in the system-model data structure, rather than as an
argument to the dynamics functions; (2) external forces are now expressed