1#include <Eigen/Dense>
2#include <iostream>
3
4using namespace std;
5
6int main()
7{
8  Eigen::MatrixXf m(4,4);
9  m <<  1, 2, 3, 4,
10        5, 6, 7, 8,
11        9,10,11,12,
12       13,14,15,16;
13  cout << "Block in the middle" << endl;
14  cout << m.block<2,2>(1,1) << endl << endl;
15  for (int i = 1; i <= 3; ++i)
16  {
17    cout << "Block of size " << i << "x" << i << endl;
18    cout << m.block(0,0,i,i) << endl << endl;
19  }
20}
21