Fig. 3.

Instantaneous speed of a travelling front for a Gaussian threshold distribution. Measured front speed for a Gaussian threshold distribution, extracted from a simulation of (3) (blue); theoretical value from (21) (red); and the threshold (4) (green), for $\kappa =5$ (top) and $\kappa =30$ (bottom). Equation (9) was truncated after 50 terms per sum. Other parameter values are ${\sigma }^2=1/\kappa$, $h_0=0.3$, $ϵ=0.01$, $L=100$