# feedback

Feedback connection of multiple models

## Syntax

## Description

returns a model object `sys`

= feedback(`sys1,sys2`

)`sys`

for the negative feedback interconnection of
model objects `sys1,sys2`

.

From the figure, the closed-loop model `sys`

has
*u* as input vector and *y* as output vector. Both
models, `sys1`

and `sys2`

, must either be continuous or
discrete with identical sample times.

## Examples

## Input Arguments

## Output Arguments

## Limitations

The feedback connection must be free of algebraic loops. For instance, if

*D*and_{1}*D*are the feedthrough matrices of_{2}`sys1`

and`sys2`

, this condition is equivalent to:*I + D*nonsingular when using negative feedback_{1}D_{2}*I − D*nonsingular when using positive feedback_{1}D_{2}

## See Also

**Introduced before R2006a**