#include "header.h"

void systemOfLinearEquations::GaussFormula()
{
    for(int i = 0 ; i < numEquations ; ++i)
    {
        double maxElement = abs(supplementMatrix[i][i]);
        int maxRow = i;

        for(int j = i + 1 ; j < numEquations ; ++j)
        {
            if(abs(supplementMatrix[j][i]) > maxElement)
            {
                maxElement = abs(supplementMatrix[j][i]);
                maxRow = j;
            }
        }

        for(int j = i ; j < numEquations + 1 ; ++j)
        {
            double temp = supplementMatrix[maxRow][j];

            supplementMatrix[maxRow][j] = supplementMatrix[i][j];

            supplementMatrix[i][j] = temp;
        }

        for(int j = i + 1 ; j < numEquations; ++j)
        {
            double multiplier = -supplementMatrix[j][i] / supplementMatrix[i][i];

            for(int k = i ; k < numEquations + 1 ; ++k)
            {
                if (i == k)
                {
                    supplementMatrix[j][k] = 0;
                }

                else
                {
                    supplementMatrix[j][k] += multiplier * supplementMatrix[i][k];
                }
            }
        }
    }

    double* solution;
    allocateArray1D(solution, numEquations);

    for(int i = numEquations - 1 ; i >= 0 ; --i)
    {
        solution[i] = supplementMatrix[i][numEquations] / supplementMatrix[i][i];

        for(int k = i - 1 ; k >= 0 ; --k)
        {
            supplementMatrix[k][numEquations] -= supplementMatrix[k][i] * solution[i];
        }
    }

    systemOfLinearEquations::getDefaultSupplementMatrix();

    cout << endl;

    for(int i = 0 ; i < numEquations ; ++i)
    {
        cout << "x" << i + 1 << " = " << solution[i]<<endl;
    }

    cout << endl;
}