y = w'*x;
    yd(i)=y;
    e(i) = y^2 - 1;
    w = w - mu * e(i) * y * x;

N = 20000;          % # symbols
h = [1,.45,-.2];    % channel impulse response
h = h/norm(h);
Le = 20;            % equalizer length
mu = .001;          % step size
snr = 30;           % snr in dB

s0 = round( rand(N,1) )*2 - 1;     % BPSK signal
s = filter(h,1,s0);                % filtered signal

% add Gaussian noise at desired snr
n = randn(N,1);
vs = var(s);
vn = vs*10^(-snr/10);
n = sqrt(vn)*n;
r = s + n;          % received signal

e = zeros(N,1);     % error
w = zeros(Le,1);    % equalizer coefficients
w(Le)=1;            % actual filter taps are flipud(w)!

yd = zeros(N,1);

for i = 1:N-Le,
    x = r(i:Le+i-1);
    y = w'*x;
    yd(i)=y;
    e(i) = y^2 - 1;
    w = w - mu * e(i) * y * x;
end