Wonderful new form of infinite series; easy solve tetration
#1
While I've been trying to develop a linear operator that works well with hyper operators; I reinvestigated the iterated derivative I was working on and made a slight modification and got a new form of infinite series

Let \( \mathcal{M} \) be referred to as the mega derivative. We define it as:

\( \mathcal{M}f = \frac{d^x f}{dt^x}_{t = 1} = \frac{1}{\Gamma(-x)} \int_{-\infty}^1 \frac{f(t)}{(1-t)^{x+1}} dt \)

We are referring to the exponential derivative; this implies the lower limit of the riemann liouville differintegral is negative infinity.

It is a linear operator; \( \mathcal{M} (\alpha f + \beta g ) = \alpha \mathcal{M} f + \beta \mathcal{M}g \)

We have

\( \mathcal{M}\,\,(^n e)^x = (^{n-1} e)^x \cdot (^n e) \)

This is because \( \mathcal{M} (a^x) = \ln(a)^x \cdot a \)

\( \mathcal{M}\,\,e^x = e \)

\( \mathcal{M} C = 0 \) for some constant C.


I'm sure everyone here sees the parallel to the power law. Using this we can make an infinite series.

\( f(x) = \sum_{k=0}^{\infty} a_k (^k e)^x \)

Easy to see that:

\( \mathcal{M}^n\,f(x) = \sum_{k=0}^{\infty}a_k (^k e)^x \prod_{i=1}^n \,\,(^{k+i} e) \)

Which allows us to say that

\( a_k = \lim_{x\to -\infty} \frac{\mathcal{M}^k\, f(x)}{\prod_{i=0}^{k} (^i e)} \)


We of course have the most powerful function: the fixpoint of the megaderivative:

\( \lambda(s) = \sum_{k=0}^{\infty} \frac{(^k e)^s}{\prod_{i=0}^{k} (^i e)} \)

This gives:

\( \mathcal{M} \lambda = \lambda \)

Or written more formally:

\( \frac{d^s \lambda(t)}{dt^s}_{t=1} = \lambda(s) \)


I'm currently putting aside research in hyper operators to investigate these series'. I think we can solve tetration with these.

In fact; we can deduce:

\( \lim_{x \to - \infty} \mathcal{M}^n \lambda(x+1) = \,\,\,^n e \)

And so tetration boils into iteration of the mega derivative at the fixpoint function.

This solution holds the recursive identity because it uses \( \ln(^s e) = (^{s-1} e) \)


This function also has the very cool result that:

\( \lambda(s+1) = \sum_{n=0}^{\infty} \frac{\lambda(n)}{n!}s^n \) or is its own generating function. So knowing it at integer arguments is enough.

I'm mostly thinking about representing tetration using these infinite series. I'm just wondering how.
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Wonderful new form of infinite series; easy solve tetration - by JmsNxn - 09/04/2012, 06:27 PM

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