%
%  Code to perform simple iteration and show cobweb plot for the Tent Map
%
%   x_{n+1} = 2(1/2-abs(1/2-x_n))   n=0,1,2,...
%
clear
clf
global nrepeat
h=figure(1);    %(NB without these 2 lines MATLAB bug gives annoying flicker)
set(h,'doublebuffer','on');
pp=input(' length of pause between cobwebs: ');
x(1) = input(' Enter the initial condition x_0: ');
nmax=input(' Enter the number of iterations: ');
nrepeat=input(' Enter repeat count for mapping: ');
amp=input(' Enter random amplitude: ');
xx=0:0.0001:1;
plot(xx,functent(xx),'r-')  % Plot function in file functent.m
hold on
plot(xx,xx,'b')  % Superpose plot of y=x
axis([0 1 0 1]);   % Scale picture
axis('square');                % Ensure plot is  square 
fprintf('\n    n       iterate \n') % Print table header
 for n = 1:nmax
  x(n+1) = functent(x(n))+amp*rand;
  fprintf('  %3.0f     %10.6f \n', n,x(n+1)) %Print iterate
    if n>1 
    xplot = [x(n-1) x(n)];
    yplot = [x(n) x(n)];
    plot(xplot,yplot,'k:')   % Draw horizontal part of cobweb
    pause(pp)
  end
  xplot = [x(n) x(n)];
  yplot = [x(n) x(n+1)];
  plot(xplot,yplot,'k')      % Draw vertical part of cobweb
  pause(pp)
end
fprintf( ' Final iteration is %10.6f \n', x(n+1)) % Has huge magnitude when
                                                  % iterates are unbounded