Quaternions in Python

[Andrew Dalke]

Paul Rubin:
>I think there's a simple way to represent quaternions as 3x3 matrices.

Thank you for giving me a chance to repeat one of my favorite
phrases from the movie "Apollo 13" -- "Gimbal lock".  (Okay,
it isn't a widely popular quote, but I like it anyway!)

For an example of what that means and why 3x3 matricies don't
work, an "I'm feeling lucky" Google search for "Gimbal lock
quaternion" yields
  http://www.anticz.com/eularqua.htm
and this link has more details,
  http://www.gamasutra.com/features/19980703/quaternions_01.htm

                    Andrew
                    dalke at dalkescientific.com