Prog

internal class Program
    {
        public delegate double Function(double x);

        public delegate double Method(Function d, double eps);

        static public double func1(double x)
        {
            return Math.Exp(x) - 4 * (1 - Math.Pow(x, 2));
        }

        static public double func2(double x)
        {
            return 1 - (1 / Math.Log(x));
        }

        static public double dihotomy(Function f, double eps)
        {
            double left = 100;
            double right = -100;
            double c = left;
            int iteration = 0;
            while (right - left > eps)
            {
                ++iteration;
                c = (left + right) / 2;
                if (f(left) * f(c) < 0)
                {
                    right = c;
                }
                else
                {
                    if (f(left) * f(c) > 0)
                        left = c;
                    else
                        return c;
                }


            }

            return c;
        }

        static public double chords(Function f, double eps)
        {
            {
                int iteration = 0;
                double x_next = 0;
                double tmp;
                double x_prev = -100;
                double x_curr = 100;

                do
                {
                    ++iteration;
                    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;
                } while (Math.Abs(x_next - x_curr) > eps);

                return x_next;
            }
        }

        static public double newton(Function f, double eps)
        {
            int iteration = 1;
            double x1 = 0;

            double delta = 1e-9;

            double der = (f(x1 + delta) - f(x1)) / delta;

            double x2 = x1 - (f(x1) / der);

            while (Math.Abs(x2-x1) > eps)
            {
                iteration += 1;
                x1 = x2;
                der = (f(x1 + delta) - f(x1)) / delta;
                x2 = x1 - (f(x1) / der);
            }

            return x2;
        }

        public static void Main(string[] args)
        {
            Function f = func1;
            Method m = newton;
            double k = m(f, 1e-10);
            Console.WriteLine(k);
        }
    }