# augstate

Append state vector to output vector

## Syntax

```asys = augstate(sys) ```

## Description

`asys = augstate(sys)` appends the state vector to the outputs of a state-space model.

Given a state-space model `sys` with equations

`$\begin{array}{l}\stackrel{˙}{x}=Ax+Bu\\ y=Cx+Du\end{array}$`

(or their discrete-time counterpart), `augstate` appends the states x to the outputs y to form the model

`$\begin{array}{c}\stackrel{˙}{x}=Ax+Bu\\ \left[\begin{array}{l}y\\ x\end{array}\right]=\left[\begin{array}{l}C\\ I\end{array}\right]x+\left[\begin{array}{l}D\\ 0\end{array}\right]u\end{array}$`

This command prepares the plant so that you can use the `feedback` command to close the loop on a full-state feedback u = −Kx.

## Limitation

Because `augstate` is only meaningful for state-space models, it cannot be used with TF, ZPK or FRD models.