¥xk = current position of particle k
¥vk = current velocity of particle k
¥pk = best position found by particle k
¥Q(x) = quality of
position x
¥g = index of
best position found so far
¥ i.e., g = argmaxk Q(pk)
¥f1, f2 = random
variables uniformly distributed over [0, 2]