I implemented the ERLS algorithm, but it don't identify true. would you help me?

clear all close all clc

global N delay Ts format long % ======================== system model ========================== % % continuous model

num = [0.00057 , 380]; den = [0.000000021437 , 0.00007633 , 1];

G = tf(num,den); pole(G); zero(G); syms z;

Ts = 0.02e-03;

Gd = c2d(G,Ts) pole(Gd); zero(Gd);

b = Gd.num{1,1}; a = Gd.den{1,1};

% identification parameters teta = [a(2:3),b(2:3)]' N = 800;

% ======================== RLS with step input ========================== %

% Rand_signal = [0.0025*randn(1,N/4) -0.0025*randn(1,N/4) zeros(1, N/2) ] ; % Rand_signal = [0.091*randn(1,200) zeros(1,600) ] ; % figure(1) % plot([0:N-1]*Ts,Rand_signal)

Rand_signal = [0.091*randn(1,N/4) -0.091*randn(1,N/4) zeros(1, N/2) ] ; % Rand_signal = [0.091*randn(1,200) zeros(1,600) ] ; figure(1) plot([0:N-1]*Ts,Rand_signal)

u = 0.126*ones(1,N) + Rand_signal; figure(2) plot([0:N-1]*Ts,u)

y = system_equation(a,b,u);

teta_hat(:,2) = zeros(4,1); % 4 parameters should be identified M=16; H=1; landa= 0.999; L=4; % R = 1e-6*eye(4,4); %sigma*eye(N).eye(N) R=1e-3*eye(4,4);

r = zeros(4,1); %Rh=z h=zeros(L,N); %solution vector alpha=H; %step size m=1;

for t = 3:N

    phi = [-y(t-1) -y(t-2) u(t-1) u(t-2)]';

 R= landa*R+ phi*phi';
 y_hat (t) = phi'*teta_hat(:,t-1);

   error(t) = y(t) - phi'*teta_hat(:,t-1);

    z  = landa*r+error(t)*phi;
   r= z;               %residual vector

for k=1:1 %itrations [~,p]=max(abs(r)); while abs(r(p))<=alpha/2*R(p,p) && m<=M m=m+1; alpha=alpha/2; end if m>M % number of bits coeffiecient break end h(p,t)=h(p,t)+sign(r(p))*alpha; r=r-sign(r(p))*alpha*R(:,p); end

h; 

    teta_hat(:,t) = teta_hat(:,t-1) + h(:,t);
end

teta_hat;

plot1(teta,teta_hat,y,y_hat)

error; cost_function_step = 0.5*(error*error'); norm(teta_hat(:,end)-teta); function y = system_equation(a,b,u)

global N delay

y = zeros(1,N);

% initial conditions y(1) = 0; y(2) = -a(2)*y(1); y(3) = -a(2)*y(2)-a(3)*y(1)+b(2)*u(1)+b(1)*u(2);

for i = 4:N y(i) = -a(2)*y(i-1)-a(3)*y(i-2)+b(2)*u(i-1)+b(3)*u(i-2); end

end