Plot problem bifurcation diagram

Hi, I would like to plot the bifurcation diagram for discrete fractional map, here is the code I wrote clear; itermax=1000; min=itermax-9;alpha=1; for beta=0:1:2 u0=0.5; u(1)=u0; for n=1:itermax u=zeros(1,n); for j=2:n u(j)=gamma(n-j+alpha)/gamma(n-j+1)*exp(-7.5*(u(j-1))^2+beta-u(j-1)); end

un=u0+ (1/gamma(alpha))*sum(u); u=[u un]; uo=un;

    end
    plot(beta*ones(10),u(min:itermax),'k.','MarkerSize',5)
    hold on
end

fsize=15; xlabel('\mu','FontSize',fsize) ylabel('\itx','FontSize',fsize) %title('r=1,k=1,l=0.3','FontSize',fsize) hold off %%%%%%%%%%%%%%%%%%%%%% However, all values are NAN. What went wrong please.