Yiannis Galidakis

Yiannis Galidakis

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6 years, 21 days
Agricultural University of Athens
Doctoral student
Athens, Greece


MaplePrimes Activity

These are Posts that have been published by Yiannis Galidakis

Spectroscopy is both qualitative and quantitative, so one can use spectral data tables of elements to do some fairly accurate Light Engineering.

Some nifty emulation of the spectral distributions of many non-LED popular lamps, which allows for direct utility calculations based on many different parameters including chromaticity, space type, lifetime, occasion, application, cost and efficiency. 7 such parameters are used with constrained weight optimization to fish out some of the more popular lamp types used in many situations today.

References (inline) the following docs:

The Science of Color, the Emission Spectra of the Elements and Some Lamp Engineering Applications


The Double Amici Prism Hand-held Spectroscope

First link main Theory, second link experimental verification.

Usage: Maple 18 main document code with library and data files. Download, unzip and run document for some quick results. Don't move library/data files relative to main doc. For further results and particular details, such as particular spectra & lamps, UN-comment the relevant commands in sections and execute individually after you have executed the entire sheet at least once.

Will be modified some time later to deal with LEDs. Based on elemental spectral data published by NIST. Suggestions 4 Improvements/Errors @ followup, here.


For sample pics generated with the above code, click on the first reference link. All pictures therein were generated using this code.




Some Maple 18 short (and I believe elegant) code for doing gravitational simulations with N bodies in space:




Initial velocities have been tweaked to keep the system stable for the duration of the animation.


Please feel free to fiddle with its parameters, velocities and positions and/or N itself, to produce more interesting animations or re-use the code therein (You can safely ignore the (c), it's there just for archiving purposes).


The following are animations from three runs with N=4, N=3 and N=2, no other parameters changed.


Hi everyone,

at the suggestion of Carl I am making my question a post.


Newbies often get fascinated with the power tower: x^x^x^...

The generalized power tower z^z^z^... is a special case of the Euler sequence:

z_{n+1}=c^z_n, for c\in C.

Like the Mandelbrot set: z_{n+1}=z^2-c, the power tower, often called infinite exponential, also has a general periodic map. It is included below and is taken from Daniel Geisler's site:

Shel and Thron proved that the infinite exponential conveges whenever c belongs to the red region, called today Shell-Thron region.

Definition of Julia Sets for the iterated exponential map:

Also like the Mandelbrot set, the infinite exponential admits Juila Sets. The Julia Sets of the infinite exponential however, are defined differently from the Julia Sets of the Mandelbrot set. They are defined to be  the closure of the periodic repellers of the Euler sequence . They are Cantor Bouquets.  Geisler's colored map then is a general map of how the corresponding Julia set behaves roughly, with c taken from the map. 

We can then introduce small cuts which go from the interior of the Shell-Thron region to the exterior, crossing at various angles, and this will tells us how the infinite exponential evolves. Generally speaking, each time one crosses the Shell-Thron boundary, one wittnesses what's called a Knaster explosion, wherein the exponential explodes into p subregions, where p is the pre-period of the multiplier.

When the parameter c exits the Shell-Thron region at angles of 2*Pi and Pi from the real axis (cuts right and left, p=1, 2), the infinite exponential either transitions from converging to a single feature to exploding into multiple indecomposable contiua (p=1), or it breaks into a period 2 bifurcation (p=2), which itself, also may explode into continua.

When it exits at angles 2*Pi/p, where p>2 is the preperiod of the multiplier, then the infinite exponential evolves from converging to a single feature, to exploding into  p major regions, called Fatou regions, each one having its own attractor, displaying a p-furcation.

In all cases,  the Knaster explosions may introduce the presence of indecomposable continua, as some Fatou regions end up covering entire parts of the complex plane after each transition. In the animations, Knaster explosions occur whenever the background is red. There may be more than one explosion present in the evolution of the power tower. 

Cantor Bouquets are strange creatures. They are essentially quantum sets, and no point of them is actually visible. The probability a point is visible varies directly with the area of the corresponding bouquet "finger" which is rendered in the area of interest. Devaney uses these "fingers"  to obtain "iteneraries" of the iterated exponential map.

Points "close"  to the fingers-hairs o the Cantor Bouquets escape towards complex infinity at (final) angles 2*Pi/p.

The "hairs" of a Cantor Bouquet are C^\infty curves, hence they can be termed easthetically pretty. Only hairs from the main Cantor bouquet for c=e^{1/e} are globally convex/concave. Every other bouquet may contain hairs which change curvature "unpredictably".

Inlcuded files:

1) Euler.mw

2) EulerAnimation.mw

3) EulerAnimation2_noaxes.mw


Code for static fractal with given parameters in 1). Parameters can be changed in the constant section (Try p=2,4 or Pi)

Code for morphing animations through cuts in the Shell-Thron region in 2). Parameters d1-d2, N

Code for zooming animations in 3). Parameters M, M1-M2,


Will show attractors of broken Fatou basins only up to pre-period p=5. No big deal though. If you want to increase the preperiod past p=5, you need to add the relavnt tests in procedure ppc(c), otherwise the new attractors are not calculated and the plot ends up red.

Colors are assigned a bit more dispersed, using ln(m). You can also use m in that place. It depends on which area you are in.

Basins of attraction and Fatou regions change appearance under different epsilons. If you want different shapes for the basins, you can try using the Manhattan metric in proc Jhf, instead of |z-lim|.

Included below are the main map of tetration by Daniel Geisler, a short excerpt of the Shell-Thron region which shows pre-periodic cuts and  6 morhing transitions, for p\in {1,2,3,4,5} and one which exits at the angle of 2 radians (p=Pi).


More than 300. To be published with my thesis. Patches, problems and code corrections in the original question page:


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