Who forbids useful commands?!? Is it an anti-homework to teach bad programming styles?
Alternatives to the break in a pseudo-loop:
exit (kills the complete Matlab sessions, but "stops the program"), quit (the same), try/catch/end (to let the code stop by error() without displaying a message. Or:
s = input('Please type in the command: ', 's');
So just type in 'return'... (evil)