--- /dev/null
+## Copyright (C) 2010 VZLU Prague
+##
+## 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 3 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 Octave; see the file COPYING. If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} sparse (@var{x})
+## Converts a block sparse matrix to (built-in) sparse.
+## @end deftypefn
+
+function sp = sparse (s)
+ bsiz = s.bsiz;
+ i = repmat (shiftdim (s.i, -2), bsiz);
+ j = repmat (shiftdim (s.j, -2), bsiz);
+ [iofs, jofs] = ndgrid (1:bsiz(1), 1:bsiz(2));
+ k = ones (1, size (s.sv, 3));
+ i = sub2ind ([bsiz(1), s.siz(1)], iofs(:,:,k), i);
+ j = sub2ind ([bsiz(2), s.siz(2)], jofs(:,:,k), j);
+
+ sp = sparse (i(:), j(:), s.sv(:), bsiz(1)*s.siz(1), bsiz(2)*s.siz(2));
+endfunction