close all 
clear all
avalues=-2:0.001:4;
N=1000; a=avalues; x=0.1;
X=zeros(N,length(a));
for n=1:.5*N 
    x=a.*x.*(1-x); 
    X(n,:)=x;
end
figure (9), hold on
for n=.5*N:N 
    x=a.*x.*(1-x); 
    X(n,:)=x;
    plot(a,x,'.','MarkerSize',0.01,'Color',[0,0,0]) 
end
hold off