 and returns its 'L' packed representation i.e., 
% a dense vector of length |n*(n+1)/2| set up by columns of the lower 
% triangle of the input matrix..
%
% *|testmex|* tests whether the behaviour of all the mex files is correct.
%
% <html><a
%  href="#top_of_page">Back to Top</a>
% </html>
%% Examples
%
% *Example 1*
% Consider the following nonlinear optimization problem
%
% $$ \min x_1^2+4x_2^2-x_3^2+x_1x_2-2x_1x_3$$
%
% subject to
%
% $$x_i\geq 0,\ \ i=1,2,3$$
%
% $$4-(x_1^2+x_2^2+x