trix  of dimensions <tt>(Nx+NYnnz) x (Nx+NYnnz)</tt> or empty matrix <tt>[]</tt>. If all three callbacks are defined, <tt>lagrhess()</tt> is used.
         </p><pre>   function [ddL, userdata] = lagrhess(x,Y,v,userdata)</pre><p>Finally, the last four callbacks serve to evaluate <tt>NANLN</tt> nonlinear and <tt>NALIN</tt> linear matrix constraints. If <tt>NANLN = NALIN = 0</tt>, they needn't be defined. Callbacks <tt>mconhess()</tt> or <tt>mconlagrhess()</tt> compute 2nd derivatives of matrix constraints and