int2

/*
Metody Numeryczne zadanie INT1
Przygotował: Dawid Grzeszuk
Kierunek: Informatyka 3 semestr
Środowisko: Visual Studio 2015
Język programowania: C#
*/

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

namespace INT
{
    class UserMatrix
    {
        private readonly double?[,] _tab;
        private readonly int _NrOfNodes;
        private readonly int _columns;

        public UserMatrix()
        {
            Console.WriteLine("Podaj stopien wielomianu:");
            _NrOfNodes = Convert.ToInt32(Console.ReadLine());
            _columns = _NrOfNodes + 1;
            _tab = new double?[_columns, 2];

            Console.Clear();
        }

        public void FillTable()
        {
            for (int x = 0; x < _columns; x++)
            {
                ShowTable();

                for (int y = 0; y < 2; y++)
                {
                    if (y == 0)
                    {
                        Console.WriteLine($"\nPodaj {x + 1} węzeł x: ");
                        _tab[x, y] = Convert.ToDouble(Console.ReadLine());
                    }
                    else if (y == 1)
                    {
                        Console.WriteLine($"\nPodaj {x + 1} węzeł y: ");
                        _tab[x, y] = Convert.ToDouble(Console.ReadLine());
                    }
                }
            }
        }

        public void ShowTable()
        {
            Console.Clear();
            Console.WriteLine("x y");
            for (int x = 0; x < _columns; x++)
            {
                for (int y = 0; y < 2; y++)
                {
                    if (_tab[x, y] == null)
                    {
                        Console.Write("- ");

                    }
                    else
                    {
                        Console.Write("{0} ", _tab[x, y]);
                    }
                }
                Console.WriteLine();
            }
        }

        public int ReturnNodes() => _NrOfNodes;
        public double?[,] ReturnMatrix() => _tab;
    }

    class ProgramMatrix
    {
        private double[,] _programTable;
        private double?[,] _userTable;
        private int _nodes;
        private double _max;
        private int _equation;

        private double Equation(double x, int n)
        {
            if (n == 0)
                return 1;
            else if (n == 1)
                return 2 * x;
            else
                return (((2 * n - 3 * x) * Equation(x, n - 1)) - ((x + 5 * n) * Equation(x, n - 2)));
        }

        public ProgramMatrix(int nodes, double?[,] matrix)
        {
            _programTable = new double[nodes + 1, nodes + 2];
            _userTable = matrix;
            _nodes = nodes;

            for (int x = 0; x < _nodes + 1; x++)
            {
                _programTable[x, 0] = 1;
                _programTable[x, 1] = 2 * _userTable[x, 0].Value;
                _programTable[x, _nodes] = _userTable[x, 1].Value;
            }

            for (int x = 0; x < _nodes + 1; x++)
            {
                for (int y = 2; y < _nodes; y++)
                {
                    _programTable[x, y] = Equation(_userTable[x, 0].Value, y);
                }
            }
        }

        public void MakeMath()
        {
            for (int column = 0; column < _nodes; column++)
            {
                _max = _programTable[column, column];
                _equation = column;

                for (int x = column; x < _nodes+1; x++)
                {
                    if (Math.Abs(_programTable[x, column]) > Math.Abs(_max))
                    {
                        _max = _programTable[x, column];
                        _equation = x;
                    }
                }

                if (Math.Abs(_max) < 1e-30)
                {
                    throw new Exception();
                }

                for (int x = column; x < _nodes + 2; x++)
                {
                    SwapElements(column, x, _equation, x);
                }

                for (int x = column; x < _nodes +2; x++)
                {
                    _programTable[column, x] = _programTable[column, x] / _max;
                }

                for (int x = 0; x < _nodes+1; x++)
                {
                    if (x != column)
                    {
                        double z = _programTable[x, column];
                        for (int y = column; y < _nodes + 1; y++)
                        {
                            _programTable[x, y] = _programTable[x, y] - z * _programTable[column, y];
                        }
                    }
                }
            }
        }

        public void SwapElements(int x1, int y1, int x2, int y2)
        {
            double temp = _programTable[x1, y1];
            _programTable[x1, y1] = _programTable[x2, y2];
            _programTable[x2, y2] = temp;
        }

        public void ShowResult()
        {
            double x, p;
            bool choice = true;

            while (choice)
            {
                Console.WriteLine("\nPodaj x: ");
                x = Convert.ToDouble(Console.ReadLine());
                p = 0;

                for (int y = 0; y < _nodes; y++)
                {
                    p = p + _programTable[y, _nodes] * Equation(x, y);
                }

                Console.WriteLine($"\nWynik to y={Math.Round(p,3)}");
                Console.WriteLine("Czy chcesz liczyć dalej? (t/n)");
                var option = Console.ReadLine();

                if (option == "t")
                {
                    choice = true;
                }
                else if (option == "n")
                {
                    choice = false;
                }
                else
                {
                    Console.Clear();
                    Console.WriteLine("Nacisnij t lub n");
                    Console.ReadKey();
                    ShowResult();
                }

                Console.Clear();
            }
        }

        public void ShowTable()
        {
            for (int x = 0; x < _nodes; x++)
            {
                for (int y = 0; y < _nodes + 1; y++)
                {
                    Console.Write($"{Math.Round(_programTable[x, y], 3)} ");
                }
                Console.WriteLine();
            }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var user = new UserMatrix();
            user.FillTable();
            var program = new ProgramMatrix(user.ReturnNodes(), user.ReturnMatrix());
            Console.Clear();
            Console.WriteLine("Macierz przed obliczeniami: ");
            program.ShowTable();
            Console.WriteLine("\nMacierz po obliczeniach: ");
            try
            {
                program.MakeMath();
                program.ShowTable();
                Console.WriteLine("\nNacisnij dowolny klawisz aby kontynuować");
                Console.ReadLine();
                Console.Clear();
                try
                {
                    program.ShowResult();
                }
                catch
                {
                    program.ShowResult();
                }
            }
            catch
            {
                Console.Clear();
                Console.WriteLine("Macierz Osobliwa");
            }
            finally
            {
                Console.WriteLine("Program wykonał swój kod");
            }
        }
    }
}