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Why it's time to embrace matrix products

Posted 9 years ago
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POSTED BY: Bill Gosper
4 Replies

The first pics remind me somehow of the behaviour of Fluoroapoatite when crystallized under certain conditions.

http://www.pharmchem.uni-muenchen.de/ac/kluefers/homepage/L/biominerals/apatite7.pdf

The observed features could be simulated by a simple "fractal"-approach, but it would be interesting whether they could be described as well by the principles used here.

POSTED BY: Hans Dolhaine
Posted 7 years ago

As I had explained in this other post, one can use Array[] to implement (finite sections of) infinite matrix products. For illustration purposes, I will demonstrate with Bill's first example.

gasketProduct[m_Integer?Positive, k_Integer, prec_: MachinePrecision] := 
      Array[Function[n, N[With[{s1 = Sin[? (1/6 - (k + 1/m)/3^n)]},
                               {{1/2 + (-1)^k s1, -Sqrt[3] Sin[? (k + 1/m)/3^n]},
                                {-s1, 1/2 - (-1)^k s1}}], prec]],
            Ceiling[20 + RealExponent[1 + Abs[k], m]], 1, Dot][[1, 1]]

base2cof[m_Integer?Positive, n_Integer?Positive, t_] := 
        Sum[gasketProduct[m, k] Exp[I ? t (k + 1/m)]/(? (k + 1/m)),
            {k, -n, n}, Method -> "Procedural"]

Just to be a little different, I'll use a pentagon as a motif:

ParametricPlot[ReIm[base2cof[5, 30, t]], {t, 0, 4 ?}, PlotPoints -> 105]

pentagonal curvy fractal

ParametricPlot[ReIm[base2cof[5, 120, t]], {t, 0, 4 ?}, MaxRecursion -> 1, PlotPoints -> 905]

even more curvy pentagonal fractal

POSTED BY: J. M.

Bill, these are very pretty, indeed, thank you very much for sharing! Here is another video hosted by Henry's channel: Developing terdragon curve.

enter image description here

POSTED BY: Marina Shchitova
POSTED BY: Sander Huisman
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