## How can I find transfer function from a difference equation?

on 28 Jun 2013

### Shashank Prasanna (view profile)

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 !

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### Shashank Prasanna (view profile)

on 28 Jun 2013

This is not a MATLAB question.

Here is some theory:

https://ccrma.stanford.edu/~jos/filters/Z_Transform_Difference_Equations.html

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

Christine Ak

### Christine Ak (view profile)

on 28 Jun 2013

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

Shashank Prasanna

### Shashank Prasanna (view profile)

on 28 Jun 2013

Please take a look at the documentation page of TF:

http://www.mathworks.com/help/control/ref/tf.html

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

Christine Ak

### Christine Ak (view profile)

on 28 Jun 2013

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