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I am looking for a function with a neutral fixed point, such that when you take a point near it and find its orbit, its cobweb diagram spirals away from it. Any ideas?

Hugh Mungus
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  • Let's try to force the fixed point to be the origin. Then, you'll to need $f(x) = -x + ?(x)$. The function $?(x)$ should satisfy $?'(0)=0$ and it should have the same sign as $-x$. It would help to have an experimental tool there's one right here if you'd like to play with it. – Mark McClure Oct 04 '17 at 14:36
  • I've been trying that with Mathematica, but I can't get anything to work out – Hugh Mungus Oct 04 '17 at 15:12

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I figured it out. The function $$f(x) = -x-x^3$$ works.

Hugh Mungus
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