function [c, cjac] = confun(mode, ncnln, n, needc, x, cjac, nstate)
% Routine to evaluate the nonlinear constraints and their 1st derivatives.

 % Function Body
 if nstate
   % First call to confun.  Set all Jacobian elements to zero.
       cjac = zeros(ncnln,n);
 end

 if needc(1) > 0
   if mode == 0 || mode == 2
     c(1) = x(1) * x(1) + x(2) * x(2) + x(3) * x(3) + x(4) * x(4);
   end
   if mode == 2
     cjac(1,1) = x(1) * 2.0;
     cjac(1,2) = x(2) * 2.0;
     cjac(1,3) = x(3) * 2.0;
     cjac(1,4) = x(4) * 2.0;
   end       
 end

 if needc(2) > 0
   
   if mode == 0 || mode == 2
     c(2) = x(1) * x(2) * x(3) * x(4);
   end
   if mode == 2
     cjac(2,1) = x(2) * x(3) * x(4);
     cjac(2,2) = x(1) * x(3) * x(4);
     cjac(2,3) = x(1) * x(2) * x(4);
     cjac(2,4) = x(1) * x(2) * x(3);
   end
 end
    
endfunction