Determinant v C++

Jednoduchý program v C++ pro vypočtení determinantu z matice (3×3).

#include <iostream>

using namespace std;
int main()
{
    int m=4, n=4, d1=0, d2=0, det;
    float mat[4][4];
    cout << "\t\t\t" << "Vitej v programu DETERMINANT\n"<< endl;

    cout << "Zadejte cisla pro vypocteni determinantu! - Matice 3x3" << endl;

        for (int i=1;i<m;i++)
        {
            for (int j=1;j<n;j++)
            {
            cout<<"Zadavate " << j << ". cislo do " << i <<". radku matice: " ; cin>> mat [i][j];
            }
        }

    det = (d1=((mat [1][1]*mat [2][2]*mat [3][3])+(mat [2][1]*mat [3][2]*mat [1][3])+(mat [3][1]*mat [1][2]*mat [2][3])))
    -(d2=((mat [1][3]*mat [2][2]*mat [3][1])+(mat [2][3]*mat [3][2]*mat [1][1])+(mat [3][3]*mat [1][2]*mat [2][1])));
    cout << "Determinant: " << det <<endl;

    return 0;
}