A period-doubling
bifurcation occurs when |
the graph of L(x) passes from inside the blue bowtie to outside,
crossing over the diagonal line. |
This introduces two new fixed points, both stable, at least before
s increases very much. |
For this 2-cycle, the original
fixed point (a 1-cycle) becomes unstable at the same s-value
that the 2-cycle appears. This is the source of the name period-doubling. |
 |
Click the picture for an animation. |