Transfer function estimation with unknown number of poles and zeros

I have an input and output signal registered in time-domain (discrete).

With

sys = tfest(data,np,Ts);

I can estimate the transfer function given the number of poles. But I don't know how many poles/zeros my transfer function should have to best fit the data.

Is there a way that MATLAB can estimate the best transfer function without these constraints?

Thank you very much.

Answer 1

[Arkadiy Turevskiy]

No, when using tfest you have to specify the number of poles and zeros.

If you are estimating state-space models, you can make use of the tool that helps you pick the order. See this example . You can then export identified state space model to MATLAB workspace and convert to a transfer function.