axis_angle_from_quaternion

compas.geometry.axis_angle_from_quaternion(q)[source]

Returns an axis and an angle of rotation from the given quaternion.

Parameters

q (list) – Quaternion as a list of four real values [qw, qx, qy, qz].

Returns

• axis (list) – Coordinates [x, y, z] of the rotation axis vector.

• angle (float) – Angle of rotation in radians.

Examples

>>> q = [1., 1., 0., 0.]
>>> axis, angle = axis_angle_from_quaternion(q)
>>> allclose(axis, [1., 0., 0.])
True
>>> allclose([angle], [math.pi/2], 1e-6)
True