We build a Mandelbrot set explorer with a Livebook
. It is an Elixir
code runner that lets you write Elixir
in the browser.
Algorithm
An explanation can be found here
Given an image with dimensions (eg w x h of 1500 x 1000), max iteration (eg 100), we want to assign to each pixel a colour which represents the "stability" of the orbit of the underlying point.
Iterate over each pixel (i,j)
:
- map it into the 2D plane: compute its "complex coordinates"
- compute the iteration number
- compute a colour
- Sum-up and draw.
Explorer
We have to parts:
- one Livebook to visualise the orbits of a point, the iterates
- one Livebook to visualise the Mandelbrot set and zoom into any point.
This is done with the Numerical Elixir
library Nx
. A solution is also proposed using embedded Zig
within the Livebook
.
The Kino.JS.Live
library makes it possible to interact with the browser.
Exploring orbits
In this Livebook, you click on a point c
of the 2D-plane and it computes the succession of points, the orbit, under the iterative map z(n+1) = z(n) * z(n) + c
and z(0)=c
.
Code source: https://github.com/ndrean/mandelbrot/blob/main/livebook/orbits.livemd
Explore the Mandelbrot set
In this Livebook, you can click into the 2D-plane to zoom into the area of interest.
We propose two solutions:
- one using only
Elixir
for the computations, - one using
Zig
for the heavy computations (you need to haveZig
installed).
Although Zig
gives you a huge boost, the performance of the Elixir
code is good. This is because we use the numerical library Nx
with the EXLA
backend.
Code source: https://github.com/ndrean/mandelbrot/blob/main/livebook/mandelbrot.livemd
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