It is very possible that I have screwed up my systems LaTeX processing (I have been playing with it recently). For example, on my system,
title('\bf My Output, \Theta');
doesn't work, but
title('\bf My Output, $\Theta$');
does. Similarly
title('Maxima {\hat V}', 'interpreter','latex')
doesn't work, but
title('Maxima ${\hat V}$', 'interpreter','latex')
does.
EDIT
Getting LaTeX to work with a legend is apparently a little tricker. Apparently, despite legend objects having an Interpreter property, it cannot be set with
plot(1:10);
h = legend('Maxima ${\hat V}$', 'Location','Best', 'interpreter','latex');
get(h, 'Interpreter')
Tells you that the interpreter is still tex. It also produces a warning
Warning: Ignoring extra legend entries.
This keys you into the fact that it is treating 'interpreter','latex' as legend entries. If instead you do
plot(1:10);
h = legend('Maxima ${\hat V}$', 'Location','Best');
set(h, 'Interpreter', 'latex')
everything is fine (despite the warnings). Even better would be
plot(1:10);
h = legend('XXX', 'Location','Best');
set(h, 'Interpreter', 'latex', 'string', 'Maxima ${\hat V}$');
which avoids all the errors also.