Given pairs of
(

*x*_{i},

*y*_{i}) with

*i*=0, 1, 2, ...,

*n* where
n is the maximum number of steps used to approximate the result of
the differential equation by the Runge-Kutta method. Then
the objective function is defined:

The sum of all y-values is the objective function that determines
the evaluation value for each chromosome.