Inverse $z$-transform of a transfer function in MATLAB I have designed a Butterworth highpass filter (HPF) of 4th order with cutoff frequency high enough to give a gain of $3$ at high frequencies. I want to find the inverse $z$-transform using MATLAB.

L=4;
OSR = 16;
[b,a] = butter(L,0.259,'high');
b = b/b(1);
fvtool(b,a);
H = tf(b,a,[],'variable','z^-1');


iztrans doesn't seem to support tf or zpk.
The function iztrans only supports symbolic expressions. This should do the trick:

[num,den] = tfdata(H);
syms z
H_sym = poly2sym(cell2mat(num),z)/poly2sym(cell2mat(den),z);
h_inv = iztrans(H_sym);