2.2. Fitness function
The fitness function is employed to evaluate the quality of the solution in successive iterations. With the use of the fitness function, a solution will be selected that optimizes an objective function. In this work, the fitness function, f(s)of solution, is calculated by the average of the error, εand the percentage of the number of weights (connections) in the network which is adapted from[15]and is given by equation(1). In the prediction problem, the er-rorε, is based on the mean squared error (MSE) or root mean squared error (RMSE) percentage expressed by equation(2),