function Psi = get_Psi(N, M, epi)
    Psi = zeros(N,M*N);
    for n = 0 : N-1
        col = zeros(1, M*N);
        Cn = floor(rand()*M);
        for q = 0 : N-1
            for p = 0:M-1
                f1 = p/M*Cn;
                f2 = q/N*n*(1+Cn*epi);
                col(q*M+p+1) = exp(1j*2*pi*(f1 + f2));
            end
        end
        Psi(n+1, :) = col;
    end
end