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Fractal Parametrization

Fractal Parametrization

Idea

Given a fractal, how do we parametrize it?

Sierpinski n-gon

Taking advantage of self-similarity, we present a simple parametrization, $S_n(t)$, of the Sierpinski n-gon in $\mathbb{C}$ based on our digit function. $$S_n(t)=\sum_{k\in\mathbb{Z}^-}R^k e^{i\frac{2 \pi D_n^k(t)}{n}},$$ for all $0\le t < 1$, where $$R=2\left(1+\sum_{k=1}^{\left\lfloor\frac{n}{4}\right\rfloor}\cos\frac{2\pi k}{n}\right).$$
$$\text{Graph 1. Interactive graph of the $K^\text{th}$ partial sum of $S_n(t)$.}$$ Some interesting cases are when $n=3$: the Sierpinski triangle, $n=4$: a space-filling variation of the Vicsek fractal, and $n\geq 5$: have boundaries that are Koch curves.

Sierpinski carpet

With a simple modification to $S_8$, we may produce a parametrization, $S_C(t)$, of the Sierpisnki carpet in $\mathbb{C}$ based on our digit function. $$S_C(t)=\sum_{k\in\mathbb{Z}^-}3^k \left[e^{i\frac{2 \pi D_8^k(t)}{8}}\right],$$ for all $0\le t < 1$, where $[\cdot]$ is the nearest integer function for Gaussian integers.
$$\text{Graph 2. Interactive graph of the $K^\text{th}$ partial sum of $S_C(t)$.}$$

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