# Rotation and transformation for a n axis by PI/4

I have the follwoing:

```
Eigen::Vector3d x_axis=..... // Heading
Eigen::Vector3d z_axis= .....
Eigen::Vector3d y_axis=z_axis.cross(x_axis).normalized();
```

how to get a rotation matrix and quaternion for these axis?? How can I do a rotation by PI/4 for this axis or the yaw rotated by PI/4... I mean I want to heading to be rotated by PI/4 so the heading will be between the x and y axises.. ???

What do you actually want as a result? An eigen representation of a rotation in any form that is a yaw angle of pi/4? There is AngleAxis that does this directly: http://eigen.tuxfamily.org/dox/classE...