Color indicates level of u, ranging from purple (lowest u values)
through blue, aqua, green, yellow and pink/red (highest u values)
Areas where u is increasing are lightened to a light pastel tone;
where u is decreasing the color is vivid.
In areas where u is changing by less than ±3×10-6 per
tu, an intermediate pastel color is seen. This includes areas that
are in steady state or equilibrium.
Wavefronts and other moving objects have decreasing u values
(brighter color) on the leading edge of the blue part of the moving
object, and increasing u (light pastel color) on the trailing edge.
This is true even for very slow-moving objects thus, you can tell
from the coloring what direction things are moving in.
''tu'' is the dimensionless unit of time, and ''lu'' the
dimensionless unit of length, implicit in the equations that define
the reaction-diffusion model. The grids for these simulations use
Δx=1/143 lu and Δt=1/2 tu; the system is 3.2 lu
wide. The simulation meets itself at the edges (periodic boundary
condition); all images tile seamlessly if used as wallpaper.