using System;


namespace нелинейная_система
{
    class Program
    {
        static void Main(string[] args)
        {
            const double eps = 0.0001;
            Console.WriteLine("Пара корней системы ");
            var xn = MPI(new double[2] { 0.6, 0.5 }, eps);
            Console.WriteLine("x=[{0}  {1}]", xn[0],xn[1]);
        }


        public static double[] MPI(double[] xn, double eps)
        {
            int counter = 0;

            while (Norma(F(xn), xn) > eps && Norma(xn) > eps)
            {
                xn = F(xn);
                Console.WriteLine("Итерация № {0} x1 = {1}  x2 = {2}", counter++, xn[0], xn[1]);
            }

            xn = new double[] { Math.Round(xn[0], 4), Math.Round(xn[1], 4) };
            return xn;
        }

        public static double[] F(double []  x) => new double[] { Math.Sqrt(1 - Math.Pow(x[1], 2)), 2 * x[0] * Math.Exp(-x[0]) };
        public static double Norma(double[] a, double[] b) => a.Diff(b).Abs().Max();
        public static double Norma(double[] a) => a.Abs().Max();


    }
    public static class MyExtension
    {
        public static double[] Diff(this double[] a, double[] b)
        {
            if (a.Length != b.Length) throw new ArgumentException();
            var ar = new double[a.Length];
            for (int i = 0; i < a.Length; ++i) ar[i] = a[i] - b[i];
            return ar;
        }

        public static double Max(this double [] a)
        {
            double max = a[0];
            foreach (var n in a) if (n > max) max = n;
            return max;
        }

        public static double[] Abs(this double[] a)
        {
            for (int i = 0; i < a.Length; ++i) a[i] *= a[i] > 0 ? 1 : -1;
            return a;
        }

    }
}