Gauss Jordan Method to Find Solution to simultaneous linear equation

C++ program for Finding Solution to Simultaneous linear equation using Gauss Jordan Method

#include<iostream>
#include<fstream>


using std::cin;
using std::cout;
using std::endl;


//make a1 -> a2
double factor(double a1,double a2){
    return (a2/a1);
}

void prog(){
    int var;
    cout<<"Enter number of variables/number of equations : ";
    cin>>var;
    cout<<"Enter equations \na1x+b1x=z1\na2x+b2x=z2 \n -- in the form -- \n  a1 b1 z1 \n  a2 b2 z2\n ";
    double arr[var+1][var+2];
    for(int i=1;i<=var;i++){
        for(int j=1;j<=var+1;j++){
            cin>>arr[i][j];
        }
    }
    int elem=1;
    for(int i=1;i<=var;i++){
        int div=arr[i][i];
        for(int j=1;j<=var+1;j++){
            if(div!=0)
            arr[i][j]=arr[i][j]/div;
            cout<<"==>"<<arr[i][j]<<"   "<<div<<endl;
        }
        if(i==var)
            break;
        for(int j=i+1;j<=var;j++){

            if(arr[j][elem]==0)
                continue;
            double rat=factor(arr[i][elem],arr[j][elem]);
            for(int k=elem;k<=(var+1);k++){
                arr[j][k]=arr[j][k]-arr[i][k]*rat;
            }
        }
        elem++;
    }



    /*for(int i=1;i<=var;i++){
        for(int j=1;j<=var+1;j++){
            cout<<arr[i][j]<<" ";
        }
        cout<<endl;
    }*/

    double ans[100]={0};
    int skip=var;
    for(int i=var;i>0;i--){
        double temp_ans=arr[i][var+1];
        for(int j=i;j<=var;j++){
            if(j==skip)
                continue;
            temp_ans-=ans[j]*arr[i][j];
        }
        if(arr[i][skip]!=0)
            ans[skip]=temp_ans/arr[i][skip];
        else
            ans[skip]=0;
        skip--;
    }
    cout<<endl;
    for(int i=1;i<=var;i++){
        cout<<"variable "<<i<<" = "<<ans[i]<<endl;
    }
}


int main(){
    //freopen("inps.txt","r",stdin);
    prog();
}

Gauss Elimination Method For Solution To simultaneous linear equation

C++ program for Gauss Elimination method to finding solutions to simultaneous linear equation in n variable.

    #include<iostream>
    #include<fstream>
     
     
    using std::cin;
    using std::cout;
    using std::endl;
     
     
    //make a1 -> a2
    double factor(double a1,double a2){
        return (a2/a1);
    }
     
    void prog(){
        int var;
        cout<<"Enter number of variables/number of equations : ";
        cin>>var;
        cout<<"Enter equations \na1x+b1x=z1\na2x+b2x=z2 \n -- in the form -- \n  a1 b1 z1 \n  a2 b2 z2\n ";
        double arr[var+1][var+2];
        for(int i=1;i<=var;i++){
            for(int j=1;j<=var+1;j++){
                cin>>arr[i][j];
            }
        }
        int elem=1;
        //converting to upper triangular form
        for(int i=1 ;i<var; i++){
            for(int j=i+1; j<=var; j++){
                if(arr[j][elem]==0)
                    continue;
                double rat=factor(arr[i][elem],arr[j][elem]);
                for(int k=elem; k<=(var+1); k++){
                    arr[j][k]=arr[j][k]-arr[i][k]*rat;
                }
            }
            elem++;
        }
        //back substitution
        double ans[100] = {0};
        int skip=var;
        for(int i=var;i>0;i--){
            double temp_ans=arr[i][var+1];
            for(int j=i;j<=var;j++){
                if(j==skip)
                    continue;
                temp_ans-=ans[j]*arr[i][j];
            }
            if(arr[i][skip]!=0)
                ans[skip]=temp_ans/arr[i][skip];
            else
                ans[skip]=0;
            skip--;
        }
        cout<<endl;
        for(int i=1;i<=var;i++){
            cout<<"variable "<<i<<" = "<<ans[i]<<endl;
        }
    }
     
     
    int main(){
        //freopen("inps.txt","r",stdin);
        prog();
    }