add boundary

fix boundary doctest

inst/@sym/boundary.m

@@ -0,0 +1,48 @@
+%% Copyright (C) 2016 Lagu
+%%
+%% This file is part of OctSymPy.
+%%
+%% OctSymPy 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 software 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 software; see the file COPYING.
+%% If not, see <http://www.gnu.org/licenses/>.
+
+%% -*- texinfo -*-
+%% @documentencoding UTF-8
+%% @defmethod @@sym boundary (@var{x})
+%% The boundary or frontier of a set.
+%%
+%% Example:
+%% @example
+%% @group
+%% a = interval (sym (1), 2);
+%% b = interval (sym (5), 8);
+%% boundary (a + b)
+%%   @result{} ans = (sym) @{1, 2, 5, 8@}
+%% @end group
+%% @end example
+%%
+%% @end defmethod
+
+
+function y = boundary(x)
+  if (nargin ~= 1)
+    print_usage ();
+  end
+  y = python_cmd ('return _ins[0].boundary,', sym (x));
+end
+
+
+%!test
+%! a = interval (sym (0), 1);
+%! b = interval (sym (0), 1, true, false);
+%! assert( isequal( boundary (a), boundary (b)))