%繪制根軌跡圖

disp('開環傳遞函數G(s)為：')
printsys(num1,den1,'s');
disp('反饋傳遞函數H(s)為:')
printsys(num2,den2,'s');
lcwin=figure('Position',[120 49 513 491],'Name','nichols曲線','NumberTitle','off',...
      'MenuBar','none');

axes('position',[0 0 1 1]);
axis off;




%設置繪圖區域
axes('Position',[.15 .33 .8 .56]);

%繪制nichols曲線
sys1=tf(num1,den1)
sys2=tf(num2,den2)
sys3=series(sys1,sys2)
nichols(sys3)
grid on
title('nichols曲線')
xlabel('開環相角')
ylabel('開環增益')