jaxtransform3d.rotations.compact_axis_angle_from_quaternion#

Compute axis-angle from quaternion.

This operation is called logarithmic map.

Parameters:

qarray-like, shape (…, 4): Unit quaternion to represent rotation: (w, x, y, z)

Returns:

aarray, shape (…, 3): Axis of rotation and rotation angle: angle * (x, y, z). The angle is constrained to [0, pi) so that the mapping is unique.

See also

quaternion_from_compact_axis_angle: Exponential map.
compact_axis_angle_from_matrix: Logarithmic map for rotation matrix.

Examples

>>> import jax.numpy as jnp
>>> from jaxtransform3d.rotations import compact_axis_angle_from_quaternion
>>> compact_axis_angle_from_quaternion(jnp.array([1., 0., 0., 0.]))
Array([0., 0., 0.], dtype=...)