using System;
using System.Diagnostics;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            int count;
            double x0 = 1;
            double x1 = 10;
            double e = 0.001;
            Stopwatch sw = new Stopwatch();
            sw.Start();
            double x = method_chord(x0, x1, e,out count);
            sw.Stop();
            Console.WriteLine("Корень = {0}\n{1}",x,count);
            Console.WriteLine(sw.Elapsed);
        }

        public static double method_chord(double x_prev, double x_curr, double e,out int count)
        {
            count = 0;
            double x_next = 0;
            double tmp; 
            while (Math.Abs(x_next - x_curr) > e)
            {
                    tmp = x_next;
                    x_next = x_curr - f(x_curr) * (x_prev - x_curr) / (f(x_prev) - f(x_curr));
                    x_prev = x_curr;
                    x_curr = tmp;
                    count++;
            }
            return x_next;
        }

        public static double f(double x)
        {
            return Math.Pow(x, 2) - 2 * x + 1;
            //return Math.Pow(x, 3) - 18 * x - 83;
           
        }
    }
}