# filt

Constructs a transfer function model in DSP format.

## Syntax

SYS = filt(NUM, DEN)

SYS = filt(NUM, DEN, Ts)

## Inputs

`NUM`- A scalar or a row vector (numerator).
`DEN`- A scalar or a row vector (denominator).
`Ts`- Sampling time Ts (in seconds).

## Outputs

- SYS
- Transfer function model in variable z
^{-1}.

## Examples

```
num = [3 4];
den = [3 1 5];
Ts = 0.2;
sys = filt(num, den, Ts)
```

`Transfer function for input 1, output 1
3 + 4 z^-1
-----------------
3 + z^-1 + 5 z^-2
Sampling Time: 0.2 s`

## Comments

Adding the `Ts` parameter allows you to define the discrete-time transfer
function.

When `NUM` and `DEN` have different lengths, the shorter
vector is treated as having trailing zeros. See tf for comparison.