# obsv

Returns the observability matrix of a state-space model.

## Syntax

OB = obsv(SYS)

OB = obsv(A, C)

## Inputs

`SYS`- Continuous-time state-space model.
`A`- The state matrix (n x n), where n is the number of states.
`C`- The output matrix (q x n), where q is the number of outputs.

## Outputs

- OB
- The observability matrix.

## Examples

```
A = [10 1;3 -5];
C = [5 0;0 6];
R = obsv(A, C)
R1 = length(A) - rank(R) % number of unobservable states
```

` ``R = [Matrix] 4 x 2
5 0
0 6
50 5
18 -30
R1 = 0`

```
sys_tf = tf([1],[2 9 3]);
sys = ss(sys_tf);
R2 = obsv(sys)
```

` ``R2 = [Matrix] 2 x 2
0 1
1 0
`

## Comments

The function returns the observability matrix of a state-space model.