[srean]

Cognoboffin is exactly right. SVD decomposed matrix into a sequence of rotation, scaling and unrotation matrices.

If anyone needs a review it's not cognoboffin.

You led with the claim you have never seen a rotation matrix in ML. I am having doubts about whether you have the ability to recognise one.

I suspect new hires get a free pass as long as they can talk a storm about backpropagation these days.