A non-simplicial Delaunay region indicates nearly cocircular or
cospherical input sites. To avoid non-simplicial regions either triangulate
the output ('<a href="qh-optq.html#Qt">Qt</a>') or joggle
the input ('<a href="qh-optq.html#QJn">QJ</a>').  Triangulated output
is more accurate than joggled input.  Alternatively, use an <a
href="qh-impre.html#exact">exact arithmetic code</a>.</p>

<p>Delaunay triangulations do not include facets that are
coplanar with the convex hull of the input sites.  A facet is
co