Integral equations

using System;
using System.Collections.Generic;
namespace Methods
{
 class Program
 {
 static double h;
 static int V = 9;
 static int a = 0;
 static int b = 1;
 static void Main(string[] args)
 {
 //структуры входных данных
 List<double> X = new List<double>();
 List<double> YResT = new List<double>();
 List<double> Fx = new List<double>();
 double determinat = 1;
 Console.Write("h = ");
 h = double.Parse(Console.ReadLine());
 int n = 0;
 //заполнение СД
 double i = a;
 while (i <= b)
 {
 X.Add(i);
 YResT.Add(V * i * i * i + i + V);
 Fx.Add(f(i));
 i += h;
 n++;
 }
 double[] YResM = new double[n];
 double[][] matrix = new double[n][];
 double[] B = new double[n];
 for (int it = 0; it < n; it++)
 {
 matrix[it] = new double[n];
 }
 for (int it = 0; it < n; it++)
 {
 B[it] = Fx[it];
 }
 for (int it = 0; it < n; it++)
 {
 for (int jt = 0; jt < n; jt++)
 {
 matrix[it][jt] = h * Ax(X[it], X[jt]);
 if (it == jt)
 {
 matrix[it][jt] += 1;
 }
 }
 }
 YResM = MetodOfGauss(matrix, B, n, 0.01, ref determinat);
 double[] Eps = new double[n];
 for (int it = 0; it < n; it++)
 {
 Eps[it] = YResT[it] - YResM[it];
 }
 Console.Write("x(k): ");
 PrintList(X);
 Console.Write("y(t): ");
 PrintList(YResT);
 Console.Write("y(m): ");
 PrintOne(YResM);
 Console.Write("e(k): ");
 PrintOne(Eps);
 Console.WriteLine("Количество узлов = {0}", n);
 Console.ReadLine();
 }
 static void PrintOne(double[] mas)
 {
 foreach (var item in mas)
 {
 Console.Write("{0:f2} ", item);
 }
 Console.WriteLine();
 }
 static void Printtwo(double[][] mas, int n)
 {
 for (int i = 0; i < n; i++)
 {
 for (int j = 0; j < n; j++)
 {
 Console.Write("{0} ", mas[i][j]);
 }
 Console.WriteLine();
 }
 }
 static double[] MetodOfGauss(double[][] matrix, double[] b, int n, double E, ref double
determinat)
 {
 double[] XResults = new double[n];
 int Count = 0;
 for (int i = 0; i < n; i++)
 {
 double p1 = matrix[i][i];
 determinat *= p1;
 if (Math.Abs(p1) <= E)
 {
 Count++;
 SwitchOfTheMAin(i, matrix, b);
 p1 = matrix[i][i];
 }
 for (int j = 0; j < n; j++)
 {
 matrix[i][j] /= p1;
 }
 b[i] /= p1;
 for (int k = i + 1; k < n; k++)
 {
 double Const = matrix[k][i]; //коэффициент - число
 for (int j = 0; j < n; j++)
 {
 matrix[k][j] -= Const * matrix[i][j];
 }
 b[k] -= Const * b[i];
 }
 XResults[n - 1] = b[n - 1];
 int CountOfS = 1;
 for (int j = n - 2; j >= 0; j--)
 {
 int k = 1;
 double Difference = 0;
 while (k <= CountOfS)
 {
 Difference += matrix[j][j + k] * XResults[j + k];
 k++;
 }
 XResults[j] = b[j] - Difference;
 CountOfS++;
 }
 }
 if (Count % 2 != 0)
 {
 determinat *= -1;
 }
 return XResults;
 }
 static void SwitchOfTheMAin(int index, double[][] matrix, double[] b)
 {
 Console.WriteLine("Мы встретили ноль в строке {0}!", index);
 double mainElement = matrix[index][index];
 int in2 = index;
 for (int i = index + 1; i < matrix.GetLength(0); i++)
 {
 if (Math.Abs(matrix[i][index]) > mainElement)
 {
 mainElement = matrix[i][index];
 in2 = i;
 }
 if (mainElement != 0)
 {
 double[] temp = new double[matrix.GetLength(1)];
 double tmp = b[index];
 {
 temp[i] = matrix[i][index];
 matrix[i][index] = matrix[i][in2];
 matrix[i][in2] = temp[i];
 }
 }
 else
 {
 Console.WriteLine("Процедура не может быть осуществлена!");
 }
 }
 }
 static void PrintList(List<double> X)
 {
 foreach (double item in X)
 {
 Console.Write("{0:f2} ", item);
 }
 Console.WriteLine();
 }
 static double f(double x)
 {
 return V * (4.0 / 3.0 * x + 0.25 * x * x + 0.2 * x * x * x);
 }
 }
}