% ͼ4-7ļ

num1 = [1 2];

den1 = conv([1 0],conv([1 1],[1 4]));

figure(1);

rlocus(num1,den1);

figure(2);

num2 = [1 1];

den2 = conv([1 0],conv([1 4],[1 2 2]));

rlocus(num2,den2);

figure(3);

num3 = [0 1];

den3 = conv([1 0],conv([1 1],[1 5]));

rlocus(num3,den3);

figure(4);

num4 = [-1 -2];

den4 = conv([1 3],[1 2 2]);

rlocus(num4,den4);

figure(5);

num5 = conv([1 1],[1 3]);

den5 = [1 0 0 0];

rlocus(num5,den5);
hold on;
num6 = -1*conv([1 1],[1 3]);

den6 = [1 0 0 0];

rlocus(num6,den6);