Source

ITE / code / shared / embedded / E4 / vech.m

function x = vech(X)
% vech     - Vectorizes the lower triangle of A.
%    v = vech(A)
% A  > (nxn) symmetric matrix.
% v  < ([n(n+1)/2]x1) vector, result of vectorization.
%
% 28/1/97

% Copyright (C) 1997 Jaime Terceiro
% 
% This program is free software; you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation; either version 2, or (at your option)
% any later version.
% 
% This program is distributed in the hope that it will be useful, but
% WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
% General Public License for more details. 
% 
% You should have received a copy of the GNU General Public License
% along with this file.  If not, write to the Free Software Foundation,
% 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

x = X(~(~tril(ones(size(X)))));