Java 1.1 Applet for the Logistic Bifurcation Diagram

The logistic equation is the mapping
xn+1 = Q(a, xn) = a xn(1 - xn)
For an initial guess x0 in the range 0 <= x0 <= 1 this defines the sequence x1, x2, ... which remains bounded (0 <= xn <= 1 for all n) as long as 0 <= a <= 4.

We are interested in plotting the long-term behavior of the sequence by plotting xm to xn for each value of a in the range aMin <= a <= aMax using the algorithm

   aMin, aMax, xMin, xMax, width, height <-- input
   skip, plot <-- input
   set up a screen window from lower left (0,0) to (width-1, height-1)
   set up a world window from lower left (aMin,xMin) to (aMin,xMax)
   skipIter <-- skip
   plotIter <-- plot
   for a from aMin to aMax in steps of (aMax-aMin)/width do
      x <-- 0.1
      for n from 1 to skipIter do 
         x <-- Q(a,x) 
      end for
      for n from 1 to plotIter do
         x <-- Q(a,x)
         plotPoint(a,x)
      end for
   end for

Applet Parameters

skip
Number of iterations to skip before plotting
plot
Number of iterations to plot
aMin
value of a for left side of window
aMax
value of a for right side of window
xMin
value of x for bottom of window
xMax
value of x for top of window

Applet Instructions

  1. Push the plot button to start the drawing
  2. Push reset button to return to default parameters
  3. To zoom in use two mouse clicks to define opposite corners of a rectangle and then push the plot button.