function boo = isstable_(sys,~)
% Checks stability

% Copyright 1986-2014 The MathWorks, Inc.
D = sys.Data_;
if nargin>1
   % Elementwise check
   boo = true(size(D));
   for ct=1:numel(D)
      [sflag,MsgID] = isstable(D(ct));
      if isnan(sflag)
         ctrlMsgUtils.error(MsgID)
      else
         boo(ct) = (sflag==1);
      end
   end
else
   boo = true;
   for ct=1:numel(D)
      [sflag,MsgID] = isstable(D(ct));
      if isnan(sflag)
         ctrlMsgUtils.error(MsgID)
      elseif ~sflag
         boo = false;  break
      end
   end
end