MATLAB Answers

Christine Ak

How can I find transfer function from a difference equation?

Asked by Christine Ak
on 28 Jun 2013
Latest activity Answered by D. Mike Daniel
on 10 Oct 2016 at 1:51

Hey,,I'm new to matlab.

I have homework says that:- y(n)=0.4142y(n-1)+0.2929x(n)+0.2929x(n-1)

find H(z) ?? Plot the poles and zeros on the z-plan with the unit circle ?

Can Somebody help me ,, Please?? thank You !



No products are associated with this question.

2 Answers

Answer by Shashank Prasanna
on 28 Jun 2013
 Accepted answer

This is not a MATLAB question.

Here is some theory:

You can certainly plug in those coefficients into tf (in the right way) and it will give you the transfer function.


Actually My Dr. want it in Matlab :/

I can't find such a way or a function to help me ! Thank You 4 ur help anyway

Please take a look at the documentation page of TF:

You can create the transfer function by passing in the right arguments. I guess that's what the doctor ordered.

Thank You Soo much I think that helps me...... :)

Answer by D. Mike Daniel
on 10 Oct 2016 at 1:51

I'm not sure I fully understand the equation. I also am not sure how to solve for the transfer function given the differential equation. I do know, however, that once you find the transfer function, you can do something like (just for example):

>> H_z = tf(1, [1 4 6])
H_z =
    s^2 + 4 s + 6
Continuous-time transfer function.
>> pzmap(H_z)

Where pzmap plots a graph of the poles (marked with "x"s) and zeros (marked with "o"s). This example has no zeros, but has poles at -2 +/- sqrt(2)*i.


Join the 15-year community celebration.

Play games and win prizes!

Learn more
Discover MakerZone

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn more

Discover what MATLAB® can do for your career.

Opportunities for recent engineering grads.

Apply Today

MATLAB Academy

New to MATLAB?

Learn MATLAB today!