Quick way to get the repelling fixed point from the attracting fixed point?
#1
So, this may seem like an odd question, but can anyone describe for me the function that takes the attracting fixed point to the repelling fixed point? I currently have a subpar manner of calculating this, and I'm wondering if there is a quicker way.

Now, to explain, let \(|\log(y)| < 1\), so for example \(y=2\). I want a function \(f\) such that \(f(2) = 4\), and similarly for the other fixed point pairs.

That is:

\[
f(y)^{1/f(y)} = y^{1/y}\\
\]

or more specifically: \(\log(f(y))/f(y) = \log(y)/y\) for the principal branch of the log.

While \(|\log(y) | < 1\) and \(|\log f(y) | > 1\)?

I feel there must be some literature on this function. So far, I've been running the protocol:

\[
f(y) = \lim_{n\to\infty} \log^{\circ n}_{y^{1/y}}(e)\\
\]

Which works pretty well, but I'm not even sure works in the general sense. Is \(e\) always in the attracting orbit of \(\log_{y^{1/y}}(z)\) of the repelling fixed point \(f(y)\)? I feel like there may be counter examples, but I'm too lazy, and my code seems to be working Rolleyes

This problems been annoying me. And it's either something gnawingly stupid that I missed, or it's a rather deep problem.

To reiterate the question. I'm looking for a function:

\[
\begin{align}
f : \{y \in \mathbb{C}\,|\,|\log(y)| < 1\} &\to \{ y \in \mathbb{C}\,|\, |\log(y)| > 1\}\\
f(y)^{1/f(y)} &= y^{1/y}\\
\end{align}
\]

I might ask this on MO, but god knows they're all a bunch of c**** there.

Regards, James

EDIT:

here's the MO question link https://mathoverflow.net/questions/42615...attracting

I'm expecting a bunch of c***** to discredit my question by tomorrow. I hate MO.
Reply


Messages In This Thread
Quick way to get the repelling fixed point from the attracting fixed point? - by JmsNxn - 07/06/2022, 09:40 PM

Possibly Related Threads…
Thread Author Replies Views Last Post
  Down with fixed points! Daniel 1 3,266 04/29/2023, 11:02 PM
Last Post: tommy1729
  Iteration with two analytic fixed points bo198214 62 84,550 11/27/2022, 06:53 AM
Last Post: JmsNxn
Question The Different Fixed Points of Exponentials Catullus 22 29,096 07/24/2022, 12:22 PM
Last Post: bo198214
  Apropos "fix"point: are the fractional iterations from there "fix" as well? Gottfried 12 17,458 07/19/2022, 03:18 AM
Last Post: JmsNxn
  Constructing an analytic repelling Abel function JmsNxn 0 3,489 07/11/2022, 10:30 PM
Last Post: JmsNxn
Question Two Attracting Fixed Points Catullus 4 7,870 07/04/2022, 01:04 PM
Last Post: tommy1729
  tetration from alternative fixed point sheldonison 22 92,852 12/24/2019, 06:26 AM
Last Post: Daniel
  Are tetrations fixed points analytic? JmsNxn 2 12,108 12/14/2016, 08:50 PM
Last Post: JmsNxn
  Derivative of exp^[1/2] at the fixed point? sheldonison 10 39,022 01/01/2016, 03:58 PM
Last Post: sheldonison
  [MSE] Fixed point and fractional iteration of a map MphLee 0 6,817 01/08/2015, 03:02 PM
Last Post: MphLee



Users browsing this thread: 1 Guest(s)