剑侠情缘经脉督脉:这段matlab程序是什么意思？

小弟完全不懂matlab呀，高人求救了！
%Delay Control with Dalin Algorithm
clear all;
close all;
ts=0.5;

%Plant
sys1=tf([1],[0.4,1],'inputdelay',0.76);
dsys1=c2d(sys1,ts,'zoh');
[num1,den1]=tfdata(dsys1,'v');

%Ideal closed loop
sys2=tf([1],[0.15,1],'inputdelay',0.76);
dsys2=c2d(sys2,ts,'zoh');

%Design Dalin controller
dsys=1/dsys1*dsys2/(1-dsys2);
[num,den]=tfdata(dsys,'v');

u_1=0.0;u_2=0.0;u_3=0.0;u_4=0.0;u_5=0.0;
y_1=0.0;

error_1=0.0;error_2=0.0;error_3=0.0;
ei=0;
for k=1:1:50
time(k)=k*ts;

rin(k)=1.0; %Tracing Step Signal

yout(k)=-den1(2)*y_1+num1(2)*u_2+num1(3)*u_3;
error(k)=rin(k)-yout(k);

M=1;
if M==1 %Using Dalin Method
u(k)=(num(1)*error(k)+num(2)*error_1+num(3)*error_2+num(4)*error_3...
-den(3)*u_1-den(4)*u_2-den(5)*u_3-den(6)*u_4-den(7)*u_5)/den(2);
elseif M==2 %Using PID Method
ei=ei+error(k)*ts;
u(k)=1.0*error(k)+0.10*(error(k)-error_1)/ts+0.50*ei;
end
%----------Return of dalin parameters------------
u_5=u_4;u_4=u_3;u_3=u_2;u_2=u_1;u_1=u(k);
y_1=yout(k);

error_3=error_2;error_2=error_1;error_1=error(k);
end
plot(time,rin,'b',time,yout,'r');
xlabel('time(s)');ylabel('rin,yout');
高手救命啊！！！！
追加你分数...
2楼的兄弟，我当然知道这是大林算法的，你就帮帮忙吧？