Error with sym('in')?

When I try sym('in') on MATLAB 2011b, I get an error:

Error using mupadmex
Error in MuPAD command: ')' expected [line 1, col 18]

Could someone explain this error to me? Is 'in' not allowed as a variable name?

Answer 1

[Walter Roberson]

That is a possibility, as it might perhaps conflict with the MuPad set membership routine 'in'; see http://www.mathworks.com/help/toolbox/mupad/stdlib/_in.html