How can I find transfer function from a difference equation?

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 !

Answer 1

[Shashank Prasanna]

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]

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]

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]

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

Answer 2

[D. Mike Daniel]

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 =

          1
    -------------
    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.

Answer 3

[yakub sharif]

Hey, I have a question If you could help

How can I get the transfer function from the equation: (2*Vm*(s*cos(theta - (2*pi)/3) - w1*sin(theta - (2*pi)/3)))/(3*(s^2 + w1^2)) + (2*Vm*(s*cos(theta + (2*pi)/3) - w1*sin(theta + (2*pi)/3)))/(3*(s^2 + w1^2)) + (2*Vm*(s*cos(theta) - w1*sin(theta)))/(3*(s^2 + w1^2))