using System;

namespace ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            double x1 = 0.1, x2 = 0.8, e = 0.0001;
            int n = 50, k = 10;
            double x, y, SN, SE;
            x = x1;
            for (int i = 1; i <= k; i++)
            {
                y = 0.5 - (Math.PI / 4 * Math.Abs(Math.Sin(x)));
                SN = 0;
                SE = 0;
                for (int j=1; j <= n; j++)
                {
                    SN = SN + (Math.Cos(2 * j * x)) / (Math.Pow(j, 2) * 4 - 1);
                }
                n = 0;
                do
                {
                    n++;
                    SE = SE + (Math.Cos(2 * n * x)) / (Math.Pow(n, 2) * 4 - 1);
                } while (Math.Abs(Math.Cos(2 * n * x) / (Math.Pow(n, 2) * 4 - 1)) > e);
                Console.WriteLine("При x={0} y={1} SN={2} SE={3}", x, y, SN, SE);
                x = x + (x2 - x1) / k;
            }
            Console.ReadLine();
        }
    }
}