TheAlgorithms-C-Plus-Plus/Computer Oriented Statistical Methods/Gaussian_elimination.cpp

#include<bits/stdc++.h>
using namespace std;

int main()
{
    int mat_size,i,j,step;

    cout<<"Matrix size: ";
    cin>>mat_size;

    double mat[mat_size+1][mat_size+1], x[mat_size][mat_size+1];

    cout<<endl<<"Enter value of the matrix: "<<endl;
    for(i=0;i<mat_size;i++)
    {
        for(j=0;j<=mat_size;j++)
        {
            cin>>mat[i][j];   //Enter (mat_size*mat_size) value of the matrix.
        }
    }

    for(step=0;step<mat_size-1;step++){
        for(i=step;i<mat_size-1;i++)
        {
            double a = (mat[i+1][step]/mat[step][step]);

            for(j=step;j<=mat_size;j++)
                mat[i+1][j] = mat[i+1][j] - (a * mat[step][j]);
        }
    }

    cout<<endl<<"Matrix using Gaussian Elimination method: "<<endl;
    for(i=0;i<mat_size;i++)
    {
        for(j=0;j<=mat_size;j++)
        {
            x[i][j] = mat[i][j];
            cout<<mat[i][j]<<" ";
        }
        cout<<endl;
    }
    cout<<endl<<"Value of the Gaussian Elimination method: "<<endl;
    for(i=mat_size-1;i>=0;i--)
    {
        double sum = 0;
        for(j=mat_size-1;j>i;j--)
        {
            x[i][j] = x[j][j] * x[i][j];
            sum = x[i][j] + sum;
        }
        if(x[i][i]==0)
            x[i][i] = 0;
        else
            x[i][i] = (x[i][mat_size] - sum)/(x[i][i]);

        cout<<"x"<<i<<"= "<<x[i][i]<<endl;
    }
return 0;
}