I meant “possible take on quaternions.doc,” of course. I am a slave to
MicroSoft Word, like every other hack. (Though at least it’s not as bad as
MS Outlook, which is *******THE MOST UNSPEAKABLY AWFUL PIECE OF SOFTWARE
EVER DEVISED BY SATAN FOR OUR TORMENT*********. Outlook story: I got one
of those irritating boxes asking me if I wanted to archive my old items.
Foolishly, I said yes. Outlook went ahead and archived every e-mail older
than one month. And do you think I can find them now? Where the hell did
the wretched program archive them? In the fifth dimension? Grrr…)
Back to quaternions. A helpful reader: “Interestingly, if one formulates
the rotation kinematics in terms of quaternions, the resultant 7×7
covariance matrix (the solution of the Riccati equation) is singular,
because of the linear dependence of the 4-parameter Euler symmetric
parameters.”
Well for heaven’s sake, everybody knows THAT.