add ainterval

inst/@sym/ainterval.m

@@ -0,0 +1,65 @@
+%% 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 ainterval (@var{x})
+%% Return the union of intervals of x when, @var{x} is in rectangular form
+%% or the union of intervals of r when self is in polar form.
+%%
+%% Example:
+%% @example
+%% @group
+%% a = interval (sym (2), 3);
+%% b = interval (sym (4), 5);
+%% ainterval (complexregion (a * b))
+%%   @result{} ans = (sym) [2, 3]
+%% @end group
+%% @end example
+%%
+%% @example
+%% @group
+%% c = interval (sym (1), 7);
+%% ainterval (complexregion (a * b + b * c))
+%%   @result{} ans = (sym) [2, 3] ∪ [4, 5]
+%% @end group
+%% @end example
+%%
+%% @end defmethod
+
+
+function y = ainterval(x)
+  if (nargin ~= 1)
+    print_usage ();
+  end
+  y = python_cmd ('return _ins[0].a_interval,', sym (x));
+end
+
+
+%!test
+%! a = interval (sym (1), 2);
+%! b = interval (sym (4), 5);
+%! k = ainterval (complexregion (a * b));
+%! assert (isequal (k, a))
+
+%!test
+%! a = interval (sym (1), 2);
+%! b = interval (sym (4), 5);
+%! c = interval (sym (-3), 2);
+%! k = ainterval (complexregion (a * b + b * c));
+%! assert (isequal (k, a + b))