Mrs Beanbag on Nostr: it's three. three axes of rotation. and it can be parametrised on the unit ball in ...

it's three. three axes of rotation. and it can be parametrised on the unit ball in R^3.

a rotation can also be represented by a unit quaternion, this is the lie algebra of SU(2) which is the double cover of SO(3). a quaternion has 4 independent variables in general. but for a unit quaternion only 3 are independent up to a sign flip (hence the double cover).