public class BracketSearch {


    public static void main (String[] argv)
    {
        bracketSearch (0, 10);
    }
    

    static void bracketSearch (double a, double b)
    {
        int M = 3;
        int N = 8;
        double bestx = a;
        double bestf = computef (bestx);
        for (int i=0; i<N; i++) {
            double delta = (b-a) / M;
            for (double x=a+delta; x<=b; x+=delta) {
                double f = computef (x);
                if (f < bestf) {
                    bestf = f;
                    bestx = x;
                }
            }
            a = bestx - delta;
            b = bestx + delta;
        }
        System.out.println ("a=" + a + " b=" + b + " bestf=" + bestf);
    }


    static double computef (double x) 
    {
        double f = 2.5 + (x - 4.71) * (x - 4.71);
        return f;
    }

}