ite. 
 <p>
 The vertex can be considered as a vector with a norm, length, inner product, cross
 product, etc. Additionally, point relations (e.g., is a point to the left of a line, the circle
 defined by this point and two others, etc.) are also defined in this class.
 <p>
 It is common to want to attach user-defined data to 
 the vertices of a subdivision.  
 One way to do this is to subclass <tt>Vertex</tt>
 to carry any desired information.
<P>

<P>
<DL>
<DT><B>Author:</B></DT>
  <DD>David Skea, Ma