1 #include <iostream>
2 #include <Eigen/Dense>
3 
4 using namespace std;
5 using namespace Eigen;
6 
main()7 int main()
8 {
9    Matrix2f A, b;
10    LLT<Matrix2f> llt;
11    A << 2, -1, -1, 3;
12    b << 1, 2, 3, 1;
13    cout << "Here is the matrix A:\n" << A << endl;
14    cout << "Here is the right hand side b:\n" << b << endl;
15    cout << "Computing LLT decomposition..." << endl;
16    llt.compute(A);
17    cout << "The solution is:\n" << llt.solve(b) << endl;
18    A(1,1)++;
19    cout << "The matrix A is now:\n" << A << endl;
20    cout << "Computing LLT decomposition..." << endl;
21    llt.compute(A);
22    cout << "The solution is now:\n" << llt.solve(b) << endl;
23 }
24