Gauss-Jordan-Matrix-Inversion-Parallelization/Gauss_Jordan_Matrix_Inversion_Parallelized.cpp at main · Grecil/Gauss-Jordan-Matrix-Inversion-Parallelization · GitHub

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#include <iostream>
#include <vector>
#include <cmath>
#include <omp.h>
using namespace std;

void printMatrix(const vector<vector<double>> &matrix)
{
    for (int i = 0; i < matrix.size(); ++i)
    {
        for (double elem : matrix[i])
        {
            cout << elem << " ";
        }
        cout << endl;
    }
    cout << endl;
}

vector<vector<double>> gaussJordanInverse(const vector<vector<double>> &matrix)
{
    int n = matrix.size();

    vector<vector<double>> augmented(n, vector<double>(2 * n, 0.0));

    #pragma omp parallel for schedule(static)
    for (int i = 0; i < n; i++)
    {

        for (int j = 0; j < n; j++)
        {
            augmented[i][j] = matrix[i][j];
        }
        augmented[i][i + n] = 1.0;
    }

    for (int i = 0; i < n; i++)
    {
        int pivot = i;

        for (int j = i + 1; j < n; j++)
        {
            if (fabs(augmented[j][i]) > fabs(augmented[pivot][i]))
            {
                pivot = j;
            }
        }

        if (pivot != i)
        {
            swap(augmented[i], augmented[pivot]);
        }

        double pivotValue = augmented[i][i];

        #pragma omp parallel for schedule(static)
        for (int j = 0; j < 2 * n; j++)
        {
            augmented[i][j] /= pivotValue;
        }

        #pragma omp parallel for schedule(static)
        for (int j = 0; j < n; j++)
        {
            if (j != i)
            {
                double factor = augmented[j][i];
                for (int k = 0; k < 2 * n; k++)
                {
                    augmented[j][k] -= factor * augmented[i][k];
                }
            }
        }
    }

    vector<vector<double>> inverse(n, vector<double>(n));
    #pragma omp parallel for schedule(static)
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            inverse[i][j] = augmented[i][j + n];
        }
    }

    return inverse;
}

int main()
{
    int n;
    cin >> n;
    vector<vector<double>> matrix(n, vector<double>(n));

    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            cin >> matrix[i][j];
        }
    }

    double start_time = omp_get_wtime();
    vector<vector<double>> inverse = gaussJordanInverse(matrix);
    double end_time = omp_get_wtime();

    cout << "Execution time: " << end_time - start_time << " seconds" << endl;
    printMatrix(inverse);

    return 0;
}