Quick way to get the repelling fixed point from the attracting fixed point?
#3
Ooooooooooooo

This looks really promising. It sucks the paper is structured in the exact opposite direction, lol. I know how to go from repelling to attracting fast, that's not too hard, as iterating the exponential will always converge, but for the repelling case this isn't so clear. I'll have to experiment with this. This analysis is a little adjacent to what I was looking for, but I think there might be something I can unearth from here.

MO, suggested that I look at \(f(y)\) about \(y = e\) because there should be a branching point centered around that point. By this you can define a function holomorphic on \(|\log(y)| \neq 1\) with a fixed/branch point at \(e\) (that may be holomorphic there), such that:

\[
f(y) : \{|\log(y)| < 1\} \to \{|\log(y)| > 1\}\\
\]

Up to here everything is possible. Someone on MO suggests I try to develop a series about \(e\) from here. Which honestly sounds like a closed form using W-Lambert and one of its branches is really possible from here. (See how the inverse of \(w^{1/w}\) is expressible in W-lambert.) I'd just have to choose a different branch of the inverse. This sounds troubling, because I hate W-Lambert, lol. I'll see if I can go on a deepdive using W-lambert.

let:

\[
F(y^{1/y}) = y\,\,\text{for}\,|\log(y)| > 1\\
\]

Where \(F\) is some W-lambert atrocity. This would actually solve my problem, and I wouldn't need \(f\). If I have an attracting fixed point, take the self root and run an inverse W-lambert trick. YA, this should work.

Now to read up how to run W-Lambert. Skipped all those lessons, lmao.

EDIT:

I answered my own question on MO at https://mathoverflow.net/questions/42615...attracting


This entirely solves the problem. But I don't know what branch of the Lambert function to use as of now.

Does anyone have a good formula for how the various branches of Lambert relate to the Lambert formula for the inverse of:

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


Messages In This Thread
RE: Quick way to get the repelling fixed point from the attracting fixed point? - by JmsNxn - 07/10/2022, 02:24 AM

Possibly Related Threads…
Thread Author Replies Views Last Post
  Down with fixed points! Daniel 1 2,756 04/29/2023, 11:02 PM
Last Post: tommy1729
  Iteration with two analytic fixed points bo198214 62 72,034 11/27/2022, 06:53 AM
Last Post: JmsNxn
Question The Different Fixed Points of Exponentials Catullus 22 24,720 07/24/2022, 12:22 PM
Last Post: bo198214
  Apropos "fix"point: are the fractional iterations from there "fix" as well? Gottfried 12 15,128 07/19/2022, 03:18 AM
Last Post: JmsNxn
  Constructing an analytic repelling Abel function JmsNxn 0 3,086 07/11/2022, 10:30 PM
Last Post: JmsNxn
Question Two Attracting Fixed Points Catullus 4 6,642 07/04/2022, 01:04 PM
Last Post: tommy1729
  tetration from alternative fixed point sheldonison 22 88,079 12/24/2019, 06:26 AM
Last Post: Daniel
  Are tetrations fixed points analytic? JmsNxn 2 11,410 12/14/2016, 08:50 PM
Last Post: JmsNxn
  Derivative of exp^[1/2] at the fixed point? sheldonison 10 36,778 01/01/2016, 03:58 PM
Last Post: sheldonison
  [MSE] Fixed point and fractional iteration of a map MphLee 0 6,452 01/08/2015, 03:02 PM
Last Post: MphLee



Users browsing this thread: 1 Guest(s)