LU Factorization

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

int main(){
//int n;
//cin>>n;
double a[10][10],x[10];
for(int i=1;i<5;i++){
    for(int j=1;j<6;j++){
        cin>>a[i][j];
    }
}

//for(int i=1;i<5;i++){
 //   for(int j=1;j<6 ;j++){
 //       cout<<a[i][j]<<" ";
 //   }
 //   cout<<endl;
//}

float u11=a[1][1];
float u12=a[1][2];
float u13=a[1][3];
float u14=a[1][4];
float l21=a[2][1]/u11;
float l31=a[3][1]/u11;
float l41=a[4][1]/u11;
float u22=a[2][2]-(a[2][1]/u11)*a[1][2];
float u23=a[2][3]-l21*a[1][3];
float u24=a[2][4]-l21*a[1][4];
float l32=(a[3][2]-l31*u12)/u22;
float u33=a[3][3]-l31*u13-l32*u23;
float u34=a[3][4]-l31*u14-l32*u24;
float l42=(a[4][2]-l41*u12)/u22;
float l43=(a[4][3]-l41*u13-l42*u23)/u33;
float u44=a[4][4]-l41*u14-l42*u24-l43*u34;
float y1=a[1][5];
float y2=a[2][5]-l21*y1;
float y3=a[3][5]-l31*y1-l32*y2;
float y4=a[4][5]-l41*y1-l42*y2-l42*y3;
float x4=(y4-l41*y1-l42*y2-l43*y3)/u44;
float x3=(y3-l31*y1-l32*y2-u34*x4)/u33;
float x2=(y2-l21*y1-u23*x3-u24*x4)/u22;
float x1=(y1-u12*x2-u13*x3-u14*x4)/u11;
cout<<x1<<" "<<x2<<" "<<x3<<" "<<x4<<endl;

return 0;
}


/*
1 2 -1 1 6
-1 1 2 1 3
2 -1 2 2 14
1 1 -1 2 8
*/