n=4; 
N=500; 
delta=0.8; 

X1=1;X2=0;X3=1;X4=0; %移位寄存器輸入Xi初T態(tài)（0101）， Yi為移位寄存器各級輸出 
m=500; %置M序列總長度 
for i=1:m %1# 
Y4=X4; Y3=X3; Y2=X2; Y1=X1; 
X4=Y3; X3=Y2; X2=Y1; 
X1=xor(Y3,Y4); %異或運算 
if Y4==0 
U(i)=-1; 
else 
U(i)=Y4; 
end 
end 
u=U; 


z=zeros(1,500); %定義輸出觀測值的長度 
for k=3:500 
z(k)=1.5*z(k-1)-0.7*z(k-2)+u(k-1)+0.5*u(k-2); %用理想輸出值作為觀測值 
end 


h = zeros(N+1,n); 
e(n)=0; 

for i=n+1:N 
y(i)=0; 
for j=1:n 
y(i)=y(i)+h(i,j).*u(i-j+1); 
tr=norm(u((i-n):i))^2; 
h(i+1,j)=h(i,j)+delta*e(i-1)*u(i-j+1)/tr; 
end 
e(i)=z(1,i)-y(i); 
end 


figure(1) 
plot(0:N-n,u(n:N)),grid 
title('x(k) input signal in V ') 
xlabel('simples') 

figure(2) 
plot(0:N-n,z(1,n:N),'r'),hold on 
%plot(0:N-n,e(n:N),'g'),hold on 
%plot(0:N-n,h(n:N,1),'b'),hold off 
grid 
title('e(k) error and y(k) output in V') 
xlabel('samples')