, sys2=1, sign=-1)

Feedback interconnection between two I/O systems.


sys1: scalar, StateSpace, TransferFunction, FRD

The primary plant.

sys2: scalar, StateSpace, TransferFunction, FRD

The feedback plant (often a feedback controller).

sign: scalar

The sign of feedback. sign = -1 indicates negative feedback, and sign = 1 indicates positive feedback. sign is an optional argument; it assumes a value of -1 if not specified.


out: StateSpace or TransferFunction



if sys1 does not have as many inputs as sys2 has outputs, or if sys2 does not have as many inputs as sys1 has outputs


if an attempt is made to perform a feedback on a MIMO TransferFunction object

See also

series, parallel


This function is a wrapper for the feedback function in the StateSpace and TransferFunction classes. It calls if sys1 is a TransferFunction object, and if sys1 is a StateSpace object. If sys1 is a scalar, then it is converted to sys2‘s type, and the corresponding feedback function is used. If sys1 and sys2 are both scalars, then is used.