For l > 3/4, the function f2 (twice-calculated function f) has two stable fixed points, which are an attractor with a double period, i.e. the period of evolution of the system doubles. Construct graphically successive iterations of the function f for l = 0.785 and make sure that the function f transforms one of the fixed points of the function f2 into another, i.e. there are two points x1* and x2*, which are transformed as follows: x1* = f(x2*), x2* = f(x1*).

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