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доброго всем времени суток
Нашел прогу решение СЛАУ методом Гаусса, но чет она сложновата для понимания, особенно я не понял зачем массив

	int **index = new int*[n];
	for (int i = 0; i < n; i++) index[i] = new int[3];

и что он делает
А также по возможности и по коду коменты раскидайте

#include <stdlib.h>
#include <math.h>
#include <stdio.h>
#include <iostream>
using namespace std;

//solve the linear system of equations A * X = rhs by using the Gauss elimination technique
// A, rhs, and n are input variables
// n is the number of equations in the system
// X is the output vector

void Gauss(double **A, double *rhs, double *X, int n)
{
	double **w = new double*[n];
	for (int i = 0; i < n; i++) w[i] = new double[n];
	int **index = new int*[n];
	for (int i = 0; i < n; i++) index[i] = new int[3];

	int nv  = 1;
	int irow = 0;
	int icol = 0;
	double pivot;
	
	for (int i = 0; i < n; i++){
		w[i][0] = rhs[i];
		index[i][2] = 0;
	}

	double determ = 1;
	for (int i = 0; i < n; i++){
		double big = 0;
		for (int j = 0; j < n; j++){
			if (index[j][2] != 1) 
				for (int k = 0; k < n; k++)
				{
					if (index[k][2] > 1)
					{
						printf("Error at Gauss-Jordan: Matrix is singular\n");
						exit(1);
					}
					if (index[k][2] < 1)
						if (fabs(A[j][k]) > big)
						{
							irow = j;
							icol = k;
							big = fabs(A[j][k]);
						}
				}
		}

		index[icol][2] += 1;
		index[icol][0] = irow;
		index[icol][1] = icol;

		if (irow != icol)
		{
			determ = -determ;
			for (int l = 0; l < n; l++)
			{
				double temp = A[irow][l];
				A[irow][l] = A[icol][l];
				A[icol][l] = temp;
			}
			if (nv > 0)
				for (int l = 0; l < nv; l++)
				{
					double temp = w[irow][l];
					w[irow][l] = w[icol][l];
					w[icol][l] = temp;
				}
		}

		pivot = A[icol][icol];
		determ *= pivot;
		A[icol][icol] = 1;

		for (int l = 0; l < n; l++)
			A[icol][l] /= pivot;
		if (nv != 0)
			for (int l = 0; l < nv; l++)
				w[icol][l] /= pivot;
		for (int l1 = 0; l1 < n; l1++){
			if (l1 != icol)
			{
				double t = A[l1][icol];
				A[l1][icol] = 0;
				for (int l = 0; l < n; l++)
					A[l1][l] -= A[icol][l]*t;
				if (nv != 0)
					for (int l = 0; l < nv; l++)
						w[l1][l] -= w[icol][l]*t;
			}
		}
	}


	for (int i = 0; i < n; i++){
		int l = n-i-1;
		if (index[l][0] != index[l][1]){
			irow = index[l][0];
			icol = index [l][1];
			for (int k = 0; k < n; k++)
			{
				double temp = A[k][irow];
				A[k][irow] = A[k][icol];
				A[k][icol] = temp;
			}
		}
	}

	for (int k = 0; k < n; k++)
		if (index[k][2] != 1){
			printf("Error at Gauss-Jordan: Matrix is singular\n");
			exit(1);
		}

	for (int i = 0; i < n; i++)
		X[i] = w[i][0];

	for (int i = 0; i < n; i++) delete [](w[i]);
	for (int i = 0; i < n; i++) delete [](index[i]);
	delete []w;
	delete []index;

}


/////////////////////////////////////////////////////////////////////////
// MAIN PROGRAM
/////////////////////////////////////////////////////////////////////////

//Solve the following system of equations
//	   x + 2*y + 3*z =  1
//	 3*x + 4*y + 5*z =  2 
//	 5*x + 6*y + 7*z =  3
int main()
{
	int n = 3;

	//make some memory allocations
	double **A = new double*[n];
	for (int i = 0; i < n; i++) A[i] = new double[n];
	double *rhs = new double[n];
	double *res = new double[n];

	//set the matrix
	for (int i = 0; i < n; i++)
	for (int j = 0; j < n; j++)
		cin>>A[i][j];

cout << "\n\n"; 
	//set the right-hand-side
	for (int i = 0; i < n; i++)
		cin>> rhs[i];


	Gauss (A,rhs,res, n);

	//print the result on the screen
	for (int i = 0; i < n; i++)
		printf("res[%d] = %e\n", i,res[i]);

	//delete the memory allocated at the beginning
	for (int i = 0; i < n; i++) delete [](A[i]);
	delete []A;
	delete []rhs;
	delete []res;

	std::cin.get();
	cin.get();
}

Заранее спасибо

[MaTBeu]

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