skrobot.coordinates.math.axis_angle_from_quaternion

skrobot.coordinates.math.axis_angle_from_quaternion(quat)

Converts a quaternion into the axis-angle representation.

Parameters:

quat (numpy.ndarray) – quaternion [w, x, y, z]

Returns:

axis_angle – axis-angle representation of vector

Return type:

numpy.ndarray

Examples

>>> from skrobot.coordinates.math import axis_angle_from_quaternion
>>> axis_angle_from_quaternion([1, 0, 0, 0])
array([0, 0, 0])
>>> axis_angle_from_quaternion([0, 7.07106781e-01, 0, 7.07106781e-01])
array([2.22144147, 0.        , 2.22144147])