English: Image 3 (state at t=100) of a sequence showing a Turing bifurcation from a noisy ground state to a hexagonal state in a two-component reaction-diffusion system of Fitzhugh-Nagumo type, generated by Dr. H. U. Bödeker.

The system reads:

${\displaystyle {\begin{array}{rl}\partial _{t}u&=d_{u}^{2}\Delta u+u-u^{3}-v+\kappa ,\\\tau \partial _{t}v&=d_{v}^{2}\Delta v+u-v\end{array}}}$

with τ = 0.1, d_u² = 0.00028, d_v² = 0.005, κ = - 0.05

and was solved using a finite-element algorithm.