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Feigenbaum constant

There are two mathematical constants called Feigenbaum constants. Both express ratios in a bifurcation diagram. $\delta = 4.6692\cdots$ is the ratio between successive bifurcation intervals, or between the diameters of successive circles on the axis of the Mandelbrot set. $\alpha = 2.5029\cdots$ is the ratio between the width of a tine and the width of one of its two subtines (except the tine closest to the fold).

These numbers apply to a large class of dynamical systems, not just to the logistic map.