Question: how to plot iztrans in matlab?
Answer: writing the code. syms z k. G = (0.6321*z^-1)/(1-1.3679*z^-1+0.3679*z^-2) g = iztrans(G, z, k) ... 
or even. syms z k. G = (0.6321*z^-1)/(1-1.3679*z^-1+0.3679*z^-2) ... 
But there is the following error: DOUBLE cannot convert the input expression into a double array. If the input expression contains a symbolic variable, use VPA.