 satisfy 
 
                     &lt; x,  normal &gt;  =  constant. 
 
                  normal is a unit vector.  constant is the distance of 
                  the plane from the origin; 
 
                     constant * normal 
 
                  is the closest point in the plane to the origin. 
 </PRE>
<h4><a name="Parameters">Parameters</a></h4>
<PRE>
 
   None. 
 </PRE>
<h4><a name="Exceptions">Exceptions</a></h4>
<PRE>
 
   Error free. 
 
   1)  The input plane MUST have been created by one of the 