How to make step response of exp function in Matlab?

Question

G = exp(-s) * (0.8*s^2+s+2)/(s^2+s);
T = feedback(ss(G),1);
step(T)

this is example from Matlab's documentation, but it's not working, when copy and paste to program, even if I declare that 's' is syms.

Answer 1

定义s使用

s = tf('s');