function [p,q]=ljd(A,B)%調(diào)用格式：a=[1 2 -3 2 1];b=[1 -4];ljd(a,b)
p=roots(A);
q=roots(B);
p=p'
q=q'
x=max(abs([p q]))
x=x+0.1
y=x
clf
hold on
axis=[-x x -y y]
axis=('square')
plot([-x x],[ 0 0])
plot([0 0],[-y,y])
plot(real(p),imag(p),'x')
plot(real(q),imag(q),'o')
title('連續(xù)系統(tǒng)零極點(diǎn)')
text(0.2,x-0.2,'虛軸jw')
text(y-0.2,0.2,'實(shí)軸')