I need help to calculate the moments of a Chebyshev

hello, I would like to calculate the moments Chebyshev image so I used the function ChebyshevPoly after I integrated in my code to calculate the moments (the name of the function is moment), but in the end the result I is all the time as result: 0. If you can help me understand my mistake or if you have a matlab code which computes the Chebyshev moments. These are the functions that I developed: ChebyshevPoly,moment,phi_j

function tk = ChebyshevPoly(n)

if n==0 tk = 1; elseif n==1 tk = [1 0]'; else

    tkm2 = zeros(n+1,1);
    tkm2(n+1) = 1;
    tkm1 = zeros(n+1,1);
    tkm1(n) = 1;

    for k=2:n

        tk = zeros(n+1,1);

        for e=n-k+1:2:n
            tk(e) = 2*tkm1(e+1) - tkm2(e);
        end

        if mod(k,2)==0
            tk(n+1) = (-1)^(k/2);
        end

        if k<n
            tkm2 = tkm1;
            tkm1 = tk;
        end

    end

end

function out=phi_j(n,N) %PHI_J Summary of this function goes here % Detailed explanation goes here

%out=factorial(2*n)*[N+n; 2*n+1]; %out=factorial(N+n)/(2*n+1)*factorial(N-n); mol=1; for i=1:n, mol=mol*(N^2-i^2); end

out=(N^2*mol)/(2*n+1)*10^-6; end

function [ T_mn ] = moment( f,n,m) %MOMENT Summary of this function goes here % Detailed explanation goes here [N,M]=size(f); som=0; for x=1:N, for y=1:M,

% Polyval(ChebyshevPoly(n),x) som = som + (Polyval(ChebyshevPoly(n),x) * Polyval (ChebyshevPoly(m),y)* f(x,y)); end end

som; % phi_j(n,N) % phi_j(m,M) % 1/(phi_j(n,N) % 1/phi_j(m,M) % (1/(phi_j(n,N))*(1/phi_j(m,M))) T_mn=(1/(phi_j(n,N)*phi_j(m,M))).*som; end

thank you