lat4.m

This is mat lab code for adaptive lattice filters.

function eo = lat4(input,d,lambda,eta,order);

% A posteriori-based error feedback RLS lattice filter
% returns the a-priori output error sequence

N = max(size(input));
M = order;



% Initialization of M-order vectors
gamma = ones(M+1,1);
b = zeros(M,1);
kappaf = zeros(M,1);
kappab = zeros(M,1);
kappa = zeros(M,1);
   
xif = (1/eta*lambda*lambda)*ones(M,1);
xib = (1/eta*lambda*lambda)*ones(M,1);
for m=0:M-1
  xib(m+1) = xib(m+1)/lambda^m;
end
      
xibo = xib;
   
for i=1:N
  gammao = gamma;          
  bo = b;
  xiboo = xibo;  
  xibo = xib;
  xifo = xif;
  gamma = ones(M+1,1);
  b(1) = input(i);
  f(1) = input(i);
  r(1) = d(i);
  for m=1:M
    xif(m) = lambda*xif(m) + (abs(f(m)))^2/gammao(m);
    xib(m) = lambda*xib(m) + (abs(b(m)))^2/gamma(m);

    gamma(m+1) = gamma(m) - abs(b(m))^2/xib(m);

    kappa(m) = (gamma(m+1)/gamma(m))*(kappa(m) + ((b(m))'*r(m))/(lambda*gamma(m)*xibo(m)));
    kappaf(m) = (gammao(m+1)/gammao(m))*(kappaf(m) + ((bo(m))'*f(m))/(lambda*gammao(m)*xiboo(m)));
    kappab(m) = (gamma(m+1)/gammao(m))*(kappab(m) + ((f(m))'*bo(m))/(lambda*gammao(m)*xifo(m)));
        
    b(m+1) = bo(m) - kappab(m)*f(m);
    f(m+1) = f(m) - kappaf(m)*bo(m);
    r(m+1) = r(m) - kappa(m)*b(m);
  end
  eo(i) = r(M+1)/gamma(M+1);
 end