SMXL (Simulink MatriX Library) it's a powerful real and complex matrix operations support for Simulink 3
(R11.1) that works fine for later versions as well.
It features :

-) Multiplication
-) Transposition
-) Singular Value Decomposition
-) Pseudo-Inversion via SVD
-) Other simple operations

All the s-functions are written in optimized level-2 c code and are fully Real Time Workshop Compatible.

A library of ROTATION MATRICES which can be very useful for simulations of rigid bodies in 3D space, is included.

There are different examples including a Variable State Space System and an adaptive multilayer neural network.