public double siecznych() {
        ArrayList x = new ArrayList();
        x.add(a);
        x.add(b);
        System.out.println("i\t| xi\t| f(xi)");
        System.out.println("------------------------------");
        System.out.println("0\t| "+x.get(0)+"\t| "+f((Double)x.get(0)));

        int i = 1;

        while(Math.abs((Double)x.get(i) - (Double)x.get(i-1)) > eps || f((Double)x.get(i)) != 0) {
            x.add((Double)x.get(i) - ((Double)x.get(i) - (Double)x.get(i-1))/(f((Double)x.get(i)-(Double)x.get(i-1))) * f((Double)x.get(i)));
            i++;
            System.out.println(i+"\t| "+x.get(i)+"\t| "+f((Double)x.get(i)));
        }

        return (Double)x.get(i);
    }