The CoinXtension library is a small extension to the easy-to-use "Coin 3D" graphics framework. It offers some additional operators for the existing data types in Coin 3D, but more importantly it extends the linear algebra capabilities of the original framework by adding the new SbXtMatrix3d data typ. This offers such useful routines as eigenvalues and QR-decomposition. It also provides a SbXtQuaternion class for quaternion representation.