Special-purpose numerical integrators for spacecraft attitude dynamics
These are example MATLAB implementations of the numerical integration algorithms in the following paper:
Zachary R. Manchester and Mason A. Peck, "Quaternion Variational Integrators for Spacecraft Dynamics," Journal of Guidance, Control, and Dynamics, Vol. 39, No. 1, pp. 69--76, doi: http://arc.aiaa.org/doi/abs/10.2514/1.G001176
To get started, try running the demo scripts.