erdata] = mconhess(x,Y,k,i,j,userdata)
   function [ddMCLk, userdata] = mconlagrhess(x,Y,k,Umlt,userdata)</pre><p>These should return:</p>
         <div>
            <ul>
               <li>a value of the <tt>k</tt>-th matrix constriant (<tt>k=1..NANLN+NALIN</tt>)   as a dense or sparse symmetric matrix <tt>Ak</tt>,
               </li>
               <li>a derivative of the <tt>k</tt>-th matrix constraint (<tt>k=1..NANLN+NALIN</tt>)   w.r.t. <tt>i</tt>-th variable (<tt>i=1..Nx+NYnnz</tt>) as a <b>sparse</b