"Quaternion.m" seems to do collision to the matlab's "quaternion" in its 2021b version.

[Orangeman1234]

I tried 7.3.2 item Cartasian Motion in Chapter 7 using 2021b version Matlab, but some error occurred, it was that "The monitored superclass "Quaternion" will give a parsing error, which is not good on the MATLAB search path may exist. ". So, I looked through the super class of "unitQuaternion" is as the "Quaternion.m". Surely, Seems "Quaternion.m" does collision with Matlab's also quaternion(https://jp.mathworks.com/help/robotics/ref/quaternion.html). I changed the class name from "Quaternion" to "baseQuaternion" and then it worked well, share the attached file.
modifiedMfile.zip