) deal(-[x(1);x(2)], userdata);
  penm.objhess = @(x,Y,userdata) deal(-eye(2,2), userdata);
  penm.mconfun  = @(x,Y,k,userdata) deal(B+A{1}*x(1)+A{2}*x(2), userdata);
  penm.mcongrad = @(x,Y,k,i,userdata) deal(A{i}, userdata);
end
%%%  
% *Example 3*
% Again a toy nonlinear SDP example, this time in six variables
%
% $$ \min x_1x_4(x_1 + x_2 +x_3) + x_3$$
%
% subject to
%
% $$x_1x_2x_3x_4 - x_5 - 25 = 0$$
%
% $$x_1^2+x_2^2+x_3^2+x_4^2-x_6-40 = 0$$
%
% $$1\leq x_i\leq 5,\ i=1,2,3,4,\quad x_i