using System;
using System.Collections.Generic;

namespace ConsoleApplication
{
    public class Gauss_method
    {
        public double[] method(double[,] sole, int dimension, out double[] result, out double[,] triangularMatrix)
            {
                int xCount, yCount, Count = 0;
                int  maxIndexY = 0;
               double Coeff;
                double maxValue = 0;
                double sum = 0;
                double[] result_el = new double[2];


                while (Count < dimension - 1)
                {
                    glav_el(sole, dimension, Count); //Вычисление главного элемента
                    maxValue = GlavElement.maxValue; //Значение максимального элемента
                    maxIndexY = GlavElement.maxIndexY;//Значение индекса максимального элемента
                    sole = ChangeLines(sole,Count,maxIndexY,dimension); //Меняем строки местами
                    sole = Zeroing(sole,Count,dimension); //Обнуление
                   Count++;
                }

                triangularMatrix =  TriangularMatrix(dimension, sole);//Треугольная матрица
                result = back_stroke(dimension, sole);// Обратный проход

                return result;
            }

            public void glav_el(double[,] sole, int dimension, int Count) //Нахождение главного элемента и его индекса
            {
                int  yCount;
                double maxValue = 0;
                int maxIndexY = Count;
                double[] max = new double[2];
                maxValue = sole[Count,Count];

                    for (yCount = Count+1; yCount <= dimension - 1; yCount++)
                    {
                        if (maxValue < sole[yCount,Count])
                        {
                            maxValue = sole[yCount,Count];
                            maxIndexY = yCount;
                        }
                    }

                GlavElement.maxIndexY = maxIndexY;
                GlavElement.maxValue = maxValue;

            }

            double[] back_stroke(int dimension, double[,] sole) //Обратных ход
            {
                double[] result = new double[dimension];
                int yCount, xCount;
                double sum;
                result[dimension - 1] = sole[dimension - 1,dimension] / sole[dimension - 1,dimension - 1]; //находим значение последнего неизвестного
                for (yCount = dimension - 2; yCount >= 0; yCount--)
                {
                    sum = 0;
                    for (xCount = dimension - 1; xCount >= yCount; xCount--)
                    {
                        sum += sole[yCount,xCount] * result[xCount];
                    }
                    result[yCount] = (sole[yCount,dimension] - sum) / sole[yCount,yCount];
                }

                return result;

            }

        double[,] ChangeLines(double[,] sole,  int Count, int maxIndexY, int dimension) //Меняем  строки  местами
        {
            double tmp;
            int xCount;
            if (Count != maxIndexY)
            {
                for (xCount = Count; xCount <= dimension; xCount++)
                {
                    tmp = sole[Count,xCount];
                    sole[Count,xCount] = sole[maxIndexY,xCount];
                    sole[maxIndexY,xCount] = tmp;
                }
            }

            return sole;
        }

        double[,] Zeroing(double[,] sole, int Count, int dimension)//Обнуление
        {
            int yCount;
            double Coeff;
            for (yCount = Count + 1; yCount <= dimension - 1; yCount++)
            {
                Coeff = -(sole[yCount,Count] / sole[Count,Count]);
                for (int k =Count ; k <= dimension; k++)
                {
                    sole[yCount, k] += sole[Count, k] * Coeff;
                }
            }
            return sole;
        }

        double[,] TriangularMatrix(int dimension,double[,]sole) //треугольная матрица
        {
            double[,] triangularMatrix = new double[dimension,dimension+1];
            int yCount, xCount;
            for (yCount = 0; yCount <= dimension - 1; yCount++)
            {
                for (xCount = 0; xCount <= dimension; xCount++)
                    triangularMatrix[yCount,xCount] = sole[yCount,xCount];
            }

            return triangularMatrix;
        }

    }

}