Square matrix in c ++ - c++

Question

I did the above code to calculate the matrix of a square matrix but it does not work, can someone explain the error to me please
#include <iostream>
using namespace std;
int main() {
int M[3][3]={{2, 4, -6}, {1, 5, 3}, {1, 3, 2}};
int n, mult;
n=3;
cout << "Matrix: " << endl;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++)
cout << M[i][j] << "\t";
cout << "\n";
}
for (int i=0; i<n; i++){
for (int j=i+1; j<n; j++){
mult=M[j][i]/M[i][i];
for (int k=i; k<n; k++){
M[j][k]=M[j][k]-mult*M[i][k];
}
}
}
cout << "Echelon matrix: " << endl;
for (int i=0; i<n; i++){
for (int j=i+1; j<n; j++){
for(int k=i; k<n; k++){
cout << M[j][k] << "\t";
cout << "\n";
}
}
}
return 0;
}

Answer 1

In this code, I replaced int by double, even if that, for this particular matrix, it would work with int.
The main problem was that the output of the result was broken, 3 loops when two only are needed.
Note that you don't check that the Gauss pivot M[i][i] is not null. The code should be completed to handle this case.
Output:
Matrix:
2 4 -6
1 5 3
1 3 2
Echelon matrix:
2 4 -6
0 3 6
0 0 3
#include <iostream>
//using namespace std;
int main() {
double M[3][3]={{2, 4, -6}, {1, 5, 3}, {1, 3, 2}};
int n = 3;
std::cout << "Matrix: " << std::endl;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++)
std::cout << M[i][j] << "\t";
std::cout << "\n";
}
for (int i = 0; i < n; i++){
for (int j = i+1; j < n; j++){
double mult = M[j][i]/M[i][i];
for (int k = i; k < n; k++){
M[j][k] = M[j][k] - mult*M[i][k];
}
}
}
std::cout << "Echelon matrix: " << std::endl;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
std::cout << M[i][j] << "\t";
}
std::cout << std::endl;
}
return 0;
}