Eigen

Here is some example code for using the Eigen library from Pushkar Kolhe! Make sure you include all the right stuff and set up the namespace, otherwise it won't work.

```
#include <iostream>
#include "Eigen/Core"
#include "Eigen/Eigen"
using namespace std;
using namespace Eigen;
int main() {
// Definitions
Vector3d U1 = Vector3d::UnitX();
Vector3d V1, V2;
Matrix3d R1, R2;
Transform<double, 3, Affine> T1;
// Assigning
V1 << 1, 2, 3;
R1 << 1, 2, 3, 4, 5, 6, 7, 8, 9;
R2 = AngleAxisd(M_PI*2/3, V1);
T1 = AngleAxisd(M_PI, U1);
Vector3d T1_trans = T1.translation();
V2 = T1*V1;
//
cout << "V1 is " << endl << V1 << endl;
cout << "V2 = Applying T1 to V1" << endl << V2 << endl;
cout << "R1 is " << endl << R1 << endl;
cout << "R2 is " << endl << R2 << endl;
cout << "T1 is " << endl << T1.matrix() << endl;
cout << "Translational part of T1 is "<< endl << T1_trans << endl;
return 0;
}
```