I. The diagram of bifurcation of the henon's function.

     To study the evolution of that dynamic system, we plot the diagram of bifurcation in the phase space. That diagram allows to visualise the
bifurcation phenomena wich is the transition of the orbit structure.  (go to program3)

For different value of the paramenter a, we plot a set of converged values of x. that means, we plot the function x=f(a) with b=0.3 and x(0)=y(0)=0.

       This map receive a real number between 0 and 1.4, then returns a real number in [-1.5, 1.5] again. The various sequencies are yielded
depending on the parameter a and the initial values x(0), y(0). We can see that if the parameter a is taken between 0 and about 0.32, the sequence x(n) converge to a fixed point xe independent on the initial value x(0) and y(0). But what happens to the sequence x(n) when parameter exceeds 0.32? As you
see with the help of the previously graph , the sequence converge to a periodique orbit of period 2. Such situation happens when the parameter a
is taken between about 0.32 and 0.9  . If you make the parameter a larger, the period of the periodic orbit will be doubled, that is 4,8,16 ...
       This is called period doubling cascade, and beyond this cascade, the stable periodic orbit dissapears and we will see Chaos if parameter a is bigger than 1.42720. As you see above, the transition of the orbit structure accordant with the change of parameter is called bifurcation phenomena.  At least, the following graph shows a zoom on the first lower branch of the bifurcation diagram :


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