%
% cob.m
%
% cobweb plot of the logistic z = rz(1-z) iterates
%
% usage    cob(r,N,p)
%
%     N = number of points
%     p = length of pause between lines
%
%  example   cob(3.8,15,1)
%
function cob(r,N,p)
z = zeros(1,N);
z(1) = rand;
x(1) = z(1);
y(1) = 0;
t = 0:.01:1;
y = r*t.*(1-t);
subplot(2,1,1)
plot(t,y,'r')
hold on
plot(t,t,'g')

for j=2:N,
   z(j) = r*z(j-1)*(1-z(j-1));
   x(j) = x(j-1);
   y(j) = z(j);
   line([x(j-1) x(j)],[y(j-1) y(j)])
   line([x(j) y(j)],[y(j) y(j)])
   x(j) = y(j);
   pause(p)
end
hold off
title(['Logistic Cobweb, r = ' num2str(r)],'fontsize',16)

subplot(2,1,2)
plot(z,'ko-')