Infinite tetration of the imaginary unit
#29
(Further looking at the (non-) periodicity...)


We can write the iteration of b_p more convenient. Remember my convention
Code:
.
p   = Pi/2                                   ~ 1.57079632679
u_p = e^(p*I)  = cos(p) + I*sin(p)           = 1*I
t_p = exp(u)   = e^e^(p*I)                   ~ 0.540302305868 + 0.841470984808*I
b_p = exp(u/t) = e^(e^(p*I - e^(p*I))     )  ~ 1.98933207608 + 1.19328219947*I


With this we can formulate another recursion, simple and based on the angular parameter p: (I swith to tex-notation because of the use of indices)

\(
\hspace{48} p_1 = p*I - \exp(p*I) = -\cos(p) + I*(p - \sin(p)) \\
\hspace{48} p_h = p_1 + \exp(p_{h-1}) \\
\)

where always

\(
\hspace{48} b_h = b^\text{\^\^h } = \exp(\exp(p_h))
\)

The iteration p_h has here the nested form to the depth h:

\(
\hspace{48} p_h = p_1 + \exp(p_1 + \exp(p_1 + \exp(p_1+ ...))))
\)

and it looks very promising, that this can be periodic or even constant only in few and possible exotic cases. Surely, that does not automatically mean, that \( b^\text{\^\^h }= \exp(\exp(p_h)) \) cannot be periodic, as the example of h and sin(h) shows, but it is a strong hint.

Additionally, we can also insert an alternative startexponent z0 as given in my other examples; we have then a small modification:

\(
\hspace{48} p_1 = p*I - \exp(p*I) \\
\hspace{48} p_2 = p_1 + \log(z0) \\
\hspace{48} p_h = p_1 + \exp(p_{h-1}) \text{ // for h>2 } \\
\\
\hspace{24} \text{ where } \\
\hspace{48} b_2 = b^{z_0} \\
\hspace{48} b_h = \exp(\exp(p_h)) = b^{b_{h-1}}
\)


Here it seems interesting, that by the recursion the initial value z0 disappears into the tail (notational) of the p1+exp(p1+exp(...))) - expression.
Also I doubt by this now, that there could be a substantial difference between the irrational and the rational periods - but well, we have the difference between binomials of integer and non-integer parameters, so....

Hmmm....

Gottfried



Added another picture:

[Image: Period4.png]

(Hmm, now it would be interesting to trace the trajectories backwards...)
Gottfried Helms, Kassel
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Messages In This Thread
Infinite tetration of the imaginary unit - by GFR - 02/10/2008, 12:09 AM
RE: Infinite tetration of the imaginary unit - by Gottfried - 06/22/2011, 09:28 AM

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