I have gone ahead, and released my 3D kinematics routines (working with rotation matrices and quaternions, analyzing data from IMUs and from marker-based tracker systems, etc) as an open-source project. - The code can be found under https://github.com/thomas-haslwanter/scikit-kinematics - The documentation under http://work.thaslwanter.at/skinematics/html/ I still have one problem, where I would really appreciate assistance: the documentation builds cleanly on my system, under Windows as well as under Linux. However, when I build the documentation on https://readthedocs.org/, the descriptions of the functions in the modules are not built. It looks as if *readthedocs* ignores the sphinx-command "func". Check for example the link for *quat.quatmult* on http://work.thaslwanter.at/skinematics/html/quat.html (correctly working) and on http://scikit-kinematics.readthedocs.org/en/latest/quat.html (link not working) If you have had any experience with *readthedocs* and have an idea what the problem could be, please let me know. Thanks, thomas