package Lecture19;

class FuncA implements MathFunction {
    public double f(double x) {
        return x*x - 2;
    }
}
public class Bracket {
    public static boolean zbrac(MathFunction func, double[] x) {
        // Versión Java de zbrac, p.352, RN
        if (x[0] == x[1]) {
            System.out.println("Rango inicial de zbrac erróneo");
            return false;
        }
        double f0= func.f(x[0]);
        double f1= func.f(x[1]);
        for (int j= 0; j < NTRY; j++) {
            if (f0*f1 < 0.0)
                return true;
            if (Math.abs(f0) < Math.abs(f1)) {
                x[0] += FACTOR*(x[0]-x[1]);
                f0= func.f(x[0]); }
            else {
                x[1] += FACTOR*(x[1]-x[0]);
                f1= func.f(x[1]); }
        }
        return true;
    }
    public static double FACTOR= 1.6;
    public static int NTRY= 50;
    
    public static void main(String[] args) {
        double[] bound= {5.0, 6.0};     // Suposición inicial (errónea) de la acotación
        boolean intervalFound= zbrac(new FuncA(), bound);
        System.out.println("¿Acotación encontrada? " + intervalFound);
        if (intervalFound)
            System.out.println("Límite inferior: " + bound[0] + " límite superior: " + bound[1]);           
        System.exit(0);        
    }
}