skrobot.coordinates.math.rotation_matrix_to_axis_angle_vector

skrobot.coordinates.math.rotation_matrix_to_axis_angle_vector(m)

Convert rotation matrix to axis-angle representation as a vector.

The magnitude of the returned vector represents the rotation angle, and its direction represents the rotation axis.

Parameters:

m (list or numpy.ndarray) – 3x3 rotation matrix

Returns:

axis_angle_vector – Axis-angle representation as a vector of shape (3,). The vector’s magnitude is the rotation angle in radians [-pi, pi], and its direction is the rotation axis.

Return type:

numpy.ndarray

Examples

>>> import numpy as np
>>> from skrobot.coordinates.math import rotation_matrix_to_axis_angle_vector
>>> rotation_matrix_to_axis_angle_vector(np.eye(3))
array([0., 0., 0.])