A fixed point is stable if nearby points iterate
toward the fixed point under graphical iteration. |
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Click the picture for an animation. |
A fixed point is stable if at the fixed point the tangent line to the graph
lies in the region between +45° and -45°. |
That is, its slope lies between +1 and -1. |
The region between these lines is shaded in blue.
If the graph crosses the diagonal inside the
blue region (on both sides), the fixed point is stable. |
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