use the exact result contains too
        much detail.</li>
    <li>Topological error occurs when the topology of mathematical
        convex hulls is broken by facet merging or vertex merging.</li>
</ul>

<p>Under imprecision, calculations may return erroneous results.
For example, roundoff error can turn a small, positive number
into a small, negative number. See Milenkovic [<a
href="index.htm#mile93">'93</a>] for a discussion of <em>strict
robust geometry</em>. Qhull does not meet Milenkovic's criterion
