fourplan augmented plant to four plants

## Syntax

    [P11, P12, P21, P22] = fourplan(P, r)

## Arguments

P

  `syslin` list (linear system)

r

  1x2 row vector, dimension of `P22`

P11,P12,P21,P22

  `syslin` lists.

## Description

Utility function.

`P` being partitioned as follows:

    P=[ P11 P12;
        P21 P22]

with `size(P22)=r` this function returns the four linear systems `P11,P12,P21,P22`.

## See also

- lqg
- lqg2stan
- lqr
- lqe
- lft