Transfer function: magnitude & phase of frequency response - Programmers Heaven

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# Transfer function: magnitude & phase of frequency response

Posts: 1Member
i need to plot the magnitude and phase of the following equation:

first, the transfer function is:
H[z]=(2z^2+1.8z)/(z^2-z+.16)

the frequency response is basically z=exp(j*omega). thus,

H[omega]=(2exp(2j*omega)+1.8exp(j*omega))/(exp^2j*omega-exp(j*omega)+.16)

hopefully, you have an idea of how the equations look like. i need to figure out how to get the magnitude of that and the phase as well. it's a pretty ugly equation, and i've tried to simplify it by partial fractions, but it doesn't really help.

any idea?

• Posts: 41Member
The result of your function is a complex number.
You don't need to simplify the function. Matlab works it
out for you, as long as the function is well written.

Test it with some points to see that it's really
working.

Use built-in function abs( ) to get the magnitude.
Use function angle( ) to get the angle.

See this example:
http://www.matrixlab-examples.com/complex-numbers.html

Good luck!