# crv2quat¶

Converts a Cartesian rotation vector,

$\vec{\psi} = \psi\,\mathbf{\hat{n}}$

into a “minimal rotation” quaternion, i.e. being the quaternion, $$\vec{\chi}$$, defined as:

$\vec{\chi}= \left[\cos\left(\frac{\psi}{2}\right),\, \sin\left(\frac{\psi}{2}\right)\mathbf{\hat{n}}\right]$

the rotation axis, $$\mathbf{\hat{n}}$$ is such that the rotation angle, $$\psi$$, is in $$[-\pi,\,\pi]$$ or, equivalently, $$\chi_0\ge0$$.

param psi

Cartesian Rotation Vector, CRV: $$\vec{\psi} = \psi\,\mathbf{\hat{n}}$$.

type psi

np.array

returns

equivalent quaternion $$\vec{\chi}$$

rtype

np.array