FUNCTION SMC_Quat1_Ln : BOOL
Computes the natural logarithm of a unit quaternion.
The result is undefined for non-unit quaternions.
Note 1: the natural logarithm of a unit quaternion has the form (0, u*theta/2). u is the axis of rotation and theta is the angle of rotation such that q represents the rotation R(u, theta).
Note 2: for the quaternion (1,0), this function returns 0.
InOut:
