Matlab caputo fractional code

Help please, im in need for a code matlab fractional i found this code but it dosnt work, if you have in idea please chare with me

% SIR fractional system using Caputo fractional derivative

clear all; close all; clc;

% Parameters

alpha = 0.8; % order of the fractional derivative

beta = 0.4; % infection rate

gamma = 0.2; % recovery rate

N = 1000; % total population

I0 = 1; % initial number of infected individuals

R0 = 0; % initial number of recovered individuals

S0 = N - I0 - R0;% initial number of susceptible individuals

tend = 10; % end time

dt = 0.01; % time step

% Initialization

t = 0:dt:tend;

Nt = length(t);

S = zeros(1, Nt);

I = zeros(1, Nt);

R = zeros(1, Nt);

S(1) = S0;

I(1) = I0;

R(1) = R0;

% Main loop

for n = 1:Nt-1

% Compute fractional derivatives using the Caputo derivative

DalphaS = CaputoDerivative(S(n),alpha,t(n),dt);

DalphaI = CaputoDerivative(I(n),alpha,t(n),dt);

DalphaR = CaputoDerivative(R(n),alpha,t(n),dt);

% Compute derivatives using standard differential equations

dSdt = -beta*S(n)*DalphaI/N;

dIdt = beta*S(n)*DalphaI/N - gamma*DalphaI;

dRdt = gamma*DalphaI;

% Update variables

S(n+1) = S(n) + dt*dSdt;

I(n+1) = I(n) + dt*dIdt;

R(n+1) = R(n) + dt*dRdt;

end

% Plot results

plot(t, S, 'r', t, I, 'g', t, R, 'b');

legend('Susceptible', 'Infected', 'Recovered');

xlabel('Time');

ylabel('Population');

title('Fractional SIR System using Caputo Derivative');

grid on;

% Caputo derivative function

function y = CaputoDerivative(f,alpha,t,dt)

% Computes the Caputo fractional derivative of order alpha

% f: function to differentiate

% alpha: order of the fractional derivative

% t: current time

% dt: time step

% Compute the intermediate values for the Caputo derivative

N = length(f);

m = floor(alpha);

A = zeros(N,N-m);

for k = m:N-1

A(k+1-m,k+1-m:k) = dt.^(-(0:k-m)).*gamma(k-m+1)./gamma(k+2-m).*(-1).^(0:k-m);

end

% Compute the Caputo derivative

y = A*f(m+1:N)';

end