classdef AClass
  properties
    A;
  end
  methods
    function obj = ChangeA(obj, a)
      obj.A = mz;
    end
    function obj = CallChangeA(obj)
      obj.ChangeA(4);
      %obj = obj.ChangeA(4);
      %ChangeA(obj, 4);
      %obj = ChangeA(obj, 4);
      % none of these works
    end
  end
end

% ------ script:
a1 = A;
a1.A = 1;
a1.ChangeA(2); % a1.A = 2

a2 = A;
a2.A = 3;
a2.CallChangeA(); % a2.A = 3 !!!  not four