Figure 5.

Stability against noise. Probability that a flock splits into M CCs after 5000 iterations, for the three variants of the model (metric, green bars; simple topological, red bars; and topological balanced, blue bars). An initially cohesive flock is left to evolve unperturbed according to equation (3.2). Owing to the presence of noise, the flock can spontaneously split giving rise to multiple sub-groups. n_c = 22 for the simple topological model; r_c = 0.72 (corresponding to ) for the metric model; and μ = 0.411 (corresponding to ) for the topological balanced model. N = 512, α = 35, β = 5, η = 1. The other parameters are set as in Grégoire et al. [22] (v₀ = 0.05, , r_e = 0.5, r_a = 0.8). 400 distinct simulation runs are performed for each histogram. (Online version in colour.)