matrix eigen c 2b 2b example

1#include <iostream>
2#include <Eigen/Dense>
3 
4using namespace Eigen;
5 
6int main()
7{
8  MatrixXd m(2,2);
9  m(0,0) = 3;
10  m(1,0) = 2.5;
11  m(0,1) = -1;
12  m(1,1) = m(1,0) + m(0,1);
13  std::cout << "Here is the matrix m:\n" << m << std::endl;
14  VectorXd v(2);
15  v(0) = 4;
16  v(1) = v(0) - 1;
17  std::cout << "Here is the vector v:\n" << v << std::endl;
18}