Biological Computation

The Never-Ending Story    ◾    269

• e constants c

1

and c

2

determine the inuence of personalbest and

globalbest, respectively. e larger c

2

, the larger the inuence of the

particle’s “private” data, whereas the larger c

1

, the larger the inu-

ence of the whole population on the behavior of each particle (the

social inuence). Initially, one could use c

1

= c

2

= 2.

• rand() is a random number between 0 and 1. Note that a dierent

random value is used for each dimension (to simplify notation this is

not reected in the formula above).

e calculation of the velocity in each dimension is done separately

and takes into account the corresponding