1 #include <iostream> 2 #include <Eigen/Dense> 3 4 using namespace std; 5 using namespace Eigen; 6 main()7int main() 8 { 9 Matrix2d A; 10 A << 2, 1, 11 2, 0.9999999999; 12 FullPivLU<Matrix2d> lu(A); 13 cout << "By default, the rank of A is found to be " << lu.rank() << endl; 14 lu.setThreshold(1e-5); 15 cout << "With threshold 1e-5, the rank of A is found to be " << lu.rank() << endl; 16 } 17