clear;
N=500;
db=25;
sh1=sqrt(10^(-db/10));
u=1.5;
error_s=zeros(1,N);
for loop=1:1
  w=0.05*ones(1,11)';
  V=sh1*randn(1,N );
  K=randn(1,N)-0.5;
  x=sign(K);
for n=3:N;
   M(n)=0.3*x(n)+0.9*x(n-1)+0.3*x(n-2);
end
   z=M+V;
for n=8:N;
   d(n)=x(n-7);
end
   a(1)=z(1)^2;
for n=2:11;
    a(n)=z(n).^2+a(n-1);
end
for n=12:N;
    a(n)=z(n).^2-z(n-11)^2+a(n-1);
end
for n=11:N;
    z1=[z(n) z(n-1) z(n-2) z(n-3) z(n-4) z(n-5) z(n-6) z(n-7) z(n-8) z(n-9) z(n-10)]';
    y(n)=w'*z1;
    e(n)=d(n)-y(n);
    w=w+u./(eps+a(n)).*z1.*conj(e(n));
end
    error_s=error_s+e.^2;
end
w
error_s=error_s./1;
n=1:N;
plot(n,error_s);
xlabel('n （當u=1.5;DB=25時）');
ylabel('e(n)^2');
title('LMS算法1次實驗誤差平方的均值曲線');