#complexdynamics

2025-08-24

wavy iteration bands that just touch each other, for hybrid quadratic Julia set where the c value varies during iteration (e.g. looping several values).

calculation inner loop snippet:

```
vec2 C1 = C;
C = c[iteration % count];
vec2 origin = C1 + vec2(100.0, 0.0);
float o = length(origin);
float e = (1.0 + 2.0 * o) / 2.0;
float r = sqrt(e * e - o * o + o) + e;
if (length(z - origin) > r) break; // escaped
z = cSqr(z) + C;
```

#JuliaSet #hybrid #EscapeTime #fractals #MathArt #CreativeCoding #GLSL #ComplexDynamics #maths

don't ask me how I derived r, I forgot to save my workings from a couple of years ago

tune 100+0i to taste (may break when small)

hybrid julia set in white with coloured interior.

the shape is surrounded by wavy iteration bands doing binary decomposition.  the edges of the bands just touch each other - they get to 0 width without excess chopping.

screenshot of android shader editor.
2025-08-24

hmm, i think the wavy escape equipotentials are from the escape circle not being centered on the middle of the shape at each stage... forgot to make notes on my derivation, so need to reverse engineer my equations in the source code to figure out how i did it. the inflected julia sets use (z-cn)^2+cn with cn typically getting larger and larger in magnitude but polynomial uses just z^2+c'n with a few small c'n in a loop, so converting might not be trivial... #InflectorGadget #maths #ComplexDynamics

2025-01-30

inspired by tavis' deep field #nebulabrot #DeepZoom images on #fractal #fractals forums, I did a little shader that for each c in the complement of the #MandelbrotSet M, colours according to how often z <- z^2 + c hits a given small target disc , weighted by derivative (as a proxy for point density).

it looks as though the hit sources are distributed everywhere near the boundary of M, which i think i can prove for target discs outside a sufficiently large esape circle, but i'm not sure how for discs nearer M. intuitively, by the time any cell pair in binary decomposition of exterior escapes, it covers an annulus with radii R, R^2, so any disc outside R will be hit by some region in every cell pair.

#math #maths #proof #ComplexDynamics

boundary of mandelbrot set and some nearby discs in shades of purple, pixelated.
रञ्जित (Ranjit Mathew)rmathew
2024-01-27

A couple of nice posts by Claude Heiland-Allen:

“Deep Zoom Theory And Practice” [2021] (mathr.co.uk/blog/2021-05-14_de).

“Deep Zoom Theory And Practice (Again)” [2022] (mathr.co.uk/blog/2022-02-21_de).

रञ्जित (Ranjit Mathew)rmathew
2024-01-27

I’ve been fascinated by the and since my college days 😍:

“The Quest To Decode The Mandelbrot Set, Math’s Famed Fractal”, Quanta (quantamagazine.org/the-quest-t).

On HN: news.ycombinator.com/item?id=3

2021-01-04

Figured out how to plot wakes implicitly.

Given a wake with parameter ray angles $s_-, s_+$, for each pixel $c$ in the image trace the dynamic rays at those angles towards the Julia set: if and only if they land together, then $c$ is in the wake.

An application of Theorem 2.5 from arxiv.org/abs/1709.09869 "A survey on MLC, Rigidity and related topics" by Anna Miriam Benini.

Previously I had been tracing the two parameter rays into a polygonal boundary and filling that using rasterization, to do: benchmark and compare the two methods in various scenarios.

#MandelbrotSet #JuliaSet #fractal #maths #ComplexDynamics #ExternalRays

3 wakes around the Mandelbrot set (exterior boundary plotted in white) plotted implicitly in red, green, blue, on a black background.

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