package MatMod;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;

public class LenaNewton {
    public static void main(String[] args) throws IOException {
        while (true) {
            double a;
            double b;
            double exp;
            int i = 0;
            System.out.println("Интервал: ");
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            String s = reader.readLine();
            a = Double.parseDouble(s);
            s = reader.readLine();
            b = Double.parseDouble(s);
            System.out.println("Exp enter");
            s = reader.readLine();
            exp = Double.parseDouble(s);
            if (checkSign(fun(a), fun(b))) {
                System.out.println("Same");
                return;
            }
            else {
                while (true) {
                    double checkF = fun(a);
                    double checkP = proizv2(a);
                    if (checkSign(checkF, checkP)) { // a = начальная точка
                        double xn = pribl(a,fun(a),proizv(a));
                        System.out.println(xn);
                        a = a - xn;
                        if (Math.abs(a) < exp) {
                            break;
                        }
                        a = xn;
                        i++;
                    }
                    else { // b = начальная точка
                        double xn = pribl(b,fun(b),proizv(b));
                        System.out.println(xn);
                        b = b - xn;
                        if (Math.abs(b) < exp) {
                            break;
                        }
                        b = xn;
                        i++;
                    }
                }
            }
            System.out.println(i);
            break;
        }
    }

    public static double pribl(double a, double b, double c) {
        return a - b/c; // где a = xk, b = f(x), c = f`(x)
    }

    public static double proizv2(double x) {
        return -Math.cos(x); // вторая производная функции
    }

    public static double fun(double x) {
        return (2 * x + Math.cos(x) - 0.5); // Сама функция
    }

    public static double proizv(double x) {
        return 2 - Math.sin(x); // первая производная
    }

    public static boolean checkSign(double x, double y) {
        return (x > 0 && y > 0) || (x < 0 && y < 0) || (x == 0 && y == 0); // проверка знака
    }
}