d be the same as <tt>length(Y)</tt>. If the field is not present, <tt>NY=0</tt>; thus <tt>Y{:}</tt>, bounds etc. will be ignored.
               </li>
            </ul>
         </div><pre> penm.NY = 3;</pre><div>
            <ul>
               <li>cell array of length <tt>NY</tt> with a nonzero pattern of each of the matrix   variables. Each matrix will be vectorized and all its nonzeros in   the lower
                  triangle will be considered as variables, the rest as constant   zeros. The utility '.