Hi, I'm using the axis_and_angle_as_r3_rotation_matrix method of scitbx.matrix.col in some Python code. Now I need to calculate the first derivative of the rotation matrix with respect to the rotation angle. Is there a function to do that somewhere in scitbx (or elsewhere in cctbx)? I had a brief look around but couldn't find anything that looked hopeful. If there isn't something there already I have some Fortran code from David Thomas that I could adapt to do this. Of course it wouldn't be very efficient in pure Python, and calculating the matrix and its derivative separately, but that's okay for now as the code is just for testing out some ideas. By the way, links to http://skal.planet-d.net/demo/matrixfaq.htm in the documentation (e.g. herehttp://cctbx.sourceforge.net/current/c_plus_plus/namespacescitbx_1_1math_1_1...) are broken. I found a document with the same name here: http://vamos.sourceforge.net/matrixfaq.htm, but I have no idea if this has the same content as the original. Cheers -- David