# rotation2crv¶

Given a rotation matrix $$C^{AB}$$ rotating the frame A onto B, the function returns the minimal size Cartesian rotation vector, $$\vec{\psi}$$ representing this rotation.

param Cab

rotation matrix $$C^{AB}$$

type Cab

np.array

returns

equivalent Cartesian rotation vector, $$\vec{\psi}$$.

rtype

np.array

Notes

this is the inverse of algebra.crv2rotation for Cartesian rotation vectors associated to rotations in the range $$[-\pi,\,\pi]$$, i.e.:

fv == algebra.rotation2crv(algebra.crv2rotation(fv))

for each Cartesian rotation vector of the form $$\vec{\psi} = \psi\,\mathbf{\hat{n}}$$ represented as fv=a*nv such that nv is a unit vector and the scalar a is in the range $$[-\pi,\,\pi]$$.