======= Control ======= Currently, :mod:`sympy.physics.control` is able to deal with LTI (Linear, time-invariant) systems. The ``TransferFunction`` class is used to represent Continuous-time Transfer functions in the Laplace domain; where Transfer functions are input to output representations of dynamic systems. The additive property is used for transfer functions in the ``Parallel`` class, and the multiplicative property is used for transfer functions in the ``Series`` class. Also, there is a ``Feedback`` class which is used to represent negative feedback interconnection between two input/output systems. MIMO systems are also supported with ``TransferFunctionMatrix`` as the base class for representing one. ``MIMOSeries``, ``MIMOParallel`` and ``MIMOFeedback`` are MIMO equivalent of ``Series``, ``Parallel`` and ``Feedback`` classes. The advantage of this symbolic Control system package is that the solutions obtained from it are highly accurate and do not rely on numerical methods to approximate the solutions. Symbolic solutions obtained are also in a compact form that can be used for further analysis.