text: function sparsity=spars(x)
  % sparsity = sparse(x)
  %
  % Returns the sparsity of the matrix/vector x. It works for sparse and dense
  % storage, too.
  
  % This file is part of SeDuMi 1.1 by Imre Polik and Oleksandr Romanko
  % Copyright (C) 2005 McMaster University, Hamilton, CANADA  (since 1.1)
  %
  % Copyright (C) 2001 Jos F. Sturm (up to 1.05R5)
  %   Dept. Econometrics & O.R., Tilburg University, the Netherlands.
  %   Supported by the Netherlands Organization for Scientific Research (NWO).
  %
  % Affiliation SeDuMi 1.03 and 1.04Beta (2000):
  %   Dept. Quantitative Economics, Maastricht University, the Netherlands.
  %
  % Affiliations up to SeDuMi 1.02 (AUG1998):
  %   CRL, McMaster University, Canada.
  %   Supported by the Netherlands Organization for Scientific Research (NWO).
  %
  % 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 of the License, 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 program; if not, write to the Free Software
  % Foundation, Inc.,  51 Franklin Street, Fifth Floor, Boston, MA
  % 02110-1301, USA
  
  if ~isempty(x)
      sparsity=nnz(x)/numel(x);
  else
      sparsity=0;
  end