">else</span>
0058         error(<span class="string">'Unknown argument.'</span>);
0059     <span class="keyword">end</span>
0060 <span class="keyword">end</span>
0061 <span class="keyword">if</span> (length(varargin) &gt; 0),  error(<span class="string">'Too many arguments.'</span>);  <span class="keyword">end</span>;
0062 <span class="keyword">if</span> (isempty(Y)),  Y = X;  <span class="keyword">end</span>;   <span class="comment">% self-distance computation</span>
0063 
0064 [M,D1] = size(X);
0065 [N,D