def test_conversion(self): # Check the conversion functions s = TransferFunction([1, 0], [1, -1]) assert_(isinstance(s.to_ss(), StateSpace)) assert_(isinstance(s.to_tf(), TransferFunction)) assert_(isinstance(s.to_zpk(), ZerosPolesGain)) # Make sure copies work assert_(TransferFunction(s) is not s) assert_(s.to_tf() is not s)