Java 1.1 Applet for Iterating the Logistic Equation

This applet can be used to experiment with iterations of the logistic equation
xk+1 = Q(a, xk) = a xk(1 - xk),   k = 0, 1, 2, ...
The initial guess x0 and the parameter a satisfy the conditions
0 <= x0 <= 1, and 0 <= a <= 4
For values in these ranges the iterations remain bounded and satisfy 0 <= xn <= 1 for all n. We are interested in the long term behavior of the sequence x0, x1, x2, ..., xk, ... for given values of a and x0.

The applet also graphically shows the iterations using a staricase and cobweb diagram. The graph shows the parabola y = ax(1 - x) and the line y=x. The sequence of iterations is shown as a sequence of lines (vertically to the parabola horizontally to the line y=x, vertically to the parabola, horizontally to the line y=x, and so on). The x values of the vertical lines correspond to the terms in the sequence. For monotone convergence to a limit we have a staircase diagram (try a=1.9), for oscillating convergence to a limit we have a cobweb diagram (try a=2.9). For values of a > 3.0 there is no convergence. Either a periodic point is obtained or chaos is obtained. Try various values of a and analyze the behavior of the logistic equation. For the long term behavior it is best to skip a lot of iterations before plotting them. The actual values of the last few iterations are shown.

Other Applet Parameters

order
If order is left at its default value of 1 then the sequence generated is xk, where k=0,1,2,.... If order is set to 2 then the sequence generated is xk, where k=0,2,4,6,..., i.e., every other iteration. In general if order is set to m then the sequence generated is xk, where k=0,m,2m,3m,...
iterations to skip
if this value is set to s then the iterations xk are calculated but not displayed until k=s. This is useful for analyzing the long term behavior.
iterations to display
this is the number of iterations to display beginning with iteration xs.