using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication24
{
    class Program
    {
        static double Fi1 (double x, double y)
        {
            return 1 + 3 * Math.Sin(Math.PI * x / 2);
        }

        static double Fi2 (double x, double y)
        {
            return 1 + Math.Sin(Math.PI * y);
        }

        public static double roundValues (double x)
        {
            return (double)Math.Round(x * 1000) / (double)1000;
        }

        static void printM(double[,] m)
        {
            for (int i = 0; i < m.GetLength(0); i++)
            {
                for (int j = 0; j < m.GetLength(1); j++)
                {
                    Console.Write(roundValues(m[j, j]) + "   ");
                }
                Console.WriteLine("");
            }
        }

        static void Main(string[] args)
        {
            int nx, ny;
            nx = 10;
            ny = 10;
            double[] x = new double[nx];
            double[] y = new double[ny];
            double[,] u = new double[nx,ny];
            double Hx, Hy, alpha, d, du, Uold, Unew;
            Hx = 0.01;
            Hy = 0.01;
            alpha = Hx / Hy;
            for (int i = 0; i < nx; i++)
            {
                x[i] = i * Hx;
                u[i, 0] = Fi1(x[i], 0);
                u[1, ny - 1] = Fi1(x[i], 1);
            }

            for(int j = 1; j < nx; j++)
            {
                y[j] = j * Hy;
                u[0, j] = Fi2(0, y[j]);
                u[nx - 1, j] = Fi2(1, y[j]);
            }
            du = 0;
            d = 0;
            do
            {
                for (int i = 1; i < nx - 1; i++)
                {
                    for (int j = 1; j < ny - 1; j++)
                    {
                        Uold = u[i, j];
                        u[i, j] = 1 / (2 * (1 + alpha * alpha)) * ((u[i, j + 1]) + u[i, j - 1] * alpha * alpha + (u[i + 1, j] + u[i - 1, j]));
                        Unew = u[i, j];
                        if (Math.Abs(Unew) < 0.0001)
                        {
                            du = Math.Abs((Unew - Uold) / Unew);
                        }
                        if (du > d)
                        {
                            d = du;
                        }
                        u[i, j] = Unew;
                    }
                }
            } while (d > 0.0001);
            printM(u);
            Console.Read();
        }
    }
}