Figure 4
The mean fitness and the diversity of the swarm population during the optimization process.
(a) The evolution of the mean fitness on the function f1, i.e., 
where N is the total number of particles, xi is the position of particle i and xopt = 1 is the optimum solution of f1. The inset shows the last steps for SIPSO and SFPSO. (b) The evolution of the population diversity σ (see main text) during the optimization processes.
