Actual formulas for tetration and its derivative
#9
Wow, I'm not so impressed at the formulas as I am finding that they converge. I played around with dozens of infinite systems before I found that my matrix equation for the super-logarithm did converge. I would like to point out, as Jay seemed to point out, that the first formula you gave was obvious. The second is not so obvious (and I still have my doubts until I can derive it), but what is obvious to me, is that given the first two formulas, the others are easily proven.

hyper4geek Wrote:TetraExp[x] == TetraExpPrime[x] / TetraExpPrime[x-1]
TetraExp[x] == ProductLog[TetraExpPrime[x+1] / TetraExpPrime[x-1]]

But until I can derive the second formula, I'll assume that it's magic Smile

On a slightly different note, your TetraExpPrime reminds me of Szekeres' mention of the Julia functional equation (FE), and I think its actually \( 1/f'(x) \) and not f'(x), but thats not the point. The point is that the first derivative of tetration or the super-logarithm is much more fundamental than the function itself, because it by-passes the requirement \( {}^{0}x = 1 \), and thus would work for any shifted-tetration as well.

Andrew Robbins


Szekeres' overview of functional equations
Reply


Messages In This Thread
RE: Actual formulas for tetration and its derivative - by andydude - 08/31/2007, 07:04 PM

Possibly Related Threads…
Thread Author Replies Views Last Post
  New formulas for iteration Nolord 1 4,595 03/23/2025, 11:42 PM
Last Post: MphLee
  Exotic fixpoint formulas tommy1729 2 4,018 06/20/2023, 10:10 PM
Last Post: tommy1729
  CONCLUSION 1 : conditions for nice tetration : second derivative !! tommy1729 6 7,059 02/23/2023, 12:56 PM
Last Post: tommy1729
Question Derivative of the Tetration Logarithm Catullus 1 3,287 07/03/2022, 07:23 AM
Last Post: JmsNxn
  On the first derivative of the n-th tetration of f(x) Luknik 5 8,822 10/28/2021, 11:53 AM
Last Post: tommy1729
  from formulas to pari implementations Xorter 3 10,721 06/04/2020, 02:08 PM
Last Post: Xorter
  Semi-exp and the geometric derivative. A criterion. tommy1729 0 5,705 09/19/2017, 09:45 PM
Last Post: tommy1729
  How to find the first negative derivative ? tommy1729 0 5,630 02/13/2017, 01:30 PM
Last Post: tommy1729
  A calculus proposition about sum and derivative tommy1729 1 7,502 08/19/2016, 12:24 PM
Last Post: tommy1729
  Derivative of exp^[1/2] at the fixed point? sheldonison 10 37,140 01/01/2016, 03:58 PM
Last Post: sheldonison



Users browsing this thread: 4 Guest(s)