% 书79页 图3-26 的计算机程序

t = [0:0.02:3];
rh = ones(size(t));

tf1 = tf([0.24,1], conv([0.25 1], conv([0.04 0.24 1],[0.0625 1])));
c1 = step(tf1,t);

tf2 = tf(25,[1  6  25]);
c2 = step(tf2, t);
plot(t, rh, 'r-', t, c1, 'b-', t, c2, 'k-');

legend(['输入信号'], ['原系统响应'], ['降阶系统响应']);

xlabel('t/s'), ylabel('h(t)');grid on;