Two lines of arithmetic, repeated a million times, draw a picture no one designed — a shape the points are pulled toward but never settle on. This is art that is computed, never copied: change one number and a whole new figure blooms. Slide the parameter (or tap) and watch it morph.
A de Jong strange attractor. Iterate xₙ₊₁ = sin(a·yₙ) − cos(b·xₙ), yₙ₊₁ = sin(c·xₙ) − cos(d·yₙ) from any start and the points are drawn onto a fractal figure — bounded by construction (each term is a sine or cosine, so |x|,|y| ≤ 2) yet never periodic: a strange attractor. With b, c, d fixed the slider sweeps a; every value paints a different, fully deterministic figure (same a → same art). The image accumulates by density as the orbit is plotted live. A fail-loud self-check throws unless the orbit stays bounded within |x|,|y| ≤ 2.
One classic 2-parameter family rendered by orbit density (true attractors are the infinite limit; the fine structure sharpens with more points). The map, the boundedness and the determinism are exact.