u = randn(1,1000);     % channel input
c = [1 -1];
x = filter(c,1,u) + randn(1,1000)*.1;     % channel output
d = filter([zeros(1,15) 1],1,u);

L = 30;
w = zeros(L,1);
mu = 0.005;


for n = L:1000,
    Xtdl = x(n:-1:n-L+1)';
    y(n) = w'*Xtdl;
    e(n) = d(n)-y(n);
    w = w + 2*mu*e(n)*Xtdl;
 end;