# I need to find difference equation and frequency response

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Noel on 15 Nov 2011
Given H(z)=(-3+z^z-1)/(1+2z^-1+3z^-2)
a) Find the difference equation
b) Plot the frequency response
Naz on 15 Nov 2011

Walter Roberson on 15 Nov 2011
However, it appears to me that your equation probably cannot be analyzed through these techniques, as it is not in the form of a ratio of polynomials. The z^z term is going to lead you to a lot of problems.

Naz on 15 Nov 2011
Difference equation (I assume that z^z-1 should be z^-1):
3y[n-2]+2y[n-1]+y[n]=-3x[n]+z[n-1]
Frequency response:
B=[-3 1];
A=[1 2 3];
[H,W] = freqz(B,A);
plot(W,H);
##### 2 CommentsShowHide 1 older comment
Walter Roberson on 15 Nov 2011
My speculation was that the z^z-1 should be z^2 - 1 but that doesn't make sense with the leading -3 . So I still don't know what was intended.

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