Hi, I try to visualize a sine wave, z-transformed in a Bode plot. The frequency shows up correctly, but the amplitude is way off - why? Thanks for your comments. Bmalp function zdemo format compact syms w Ts n z phi t Ts = 1 w = 0.1 phi = 0 vz = simplify(ztrans(sin(w*n*Ts+phi))) % correct if 0 % method 1 [num,den] = numden(simplify(vz)); num = collect(num,'z') den = collect(den,'z') num1 = sym2poly(num) den1 = sym2poly(den) [h,w] = freqz(num1,den1,512,'whole'); else % method 2 fs = 1; f = linspace(0,fs,256); w = 2*pi*f; ss = sqrt(-1)*w; Z = exp(ss/fs); h = double(subs(vz,z,Z)); end plot(w,abs(h)) % amplitude way too big