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How Quaternions encode rotations: derivation and sample code
In the post on matrices in Codea I mentionned that an affine transformation (things like rotation, scaling, translation) ℝ 3 → ℝ 3 could be specified by giving four vectors. In this post I want to examine that a little more closely for the special case of a rotation. That is to say: how can I encode a rotation in ℝ 3…