

Unit Vector Math for 3D Graphics (2001) - fmax30
http://www.jmargolin.com/uvmath/uvmath.htm

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DonHopkins
Thanks for the excellent explanation!

"Defective matrices are rare. If you pick a random matrix it is highly
unlikely (almost impossible) to be defective. Instead, you can think of these
are ones where things line up "just right" to eliminate some information."

Is that related to "gimbal lock"? -- where the rotations line up to eliminate
a degree of freedom.

