Function quaternion_core::to_axis_angle

pub fn to_axis_angle<T>(q: Quaternion<T>) -> (Vector3<T>, T) where
    T: Float, 

Calculate the rotation axis (unit vector) and the rotation angle[rad] around the axis from the Versor.

If identity quaternion is entered, angle returns zero and the axis returns a zero vector.

Range of angle: (-π, π]