Wolfgang Meiners wrote the following on 3/31/2014 5:40 PM:
CP(a,b):= [a[2]*b[3]-a[3]*b[2], a[3]*b[1]-a[1]!
 !<-- I removed this symbol
 *b[3], a[1]*b[2]-a[2]*b[1]];

Yes, CP(b,a) hangs on mine too. As does CP(p,q). I don't see why you would expect this to not cause problems, since Maxima does not know if the arguments are lists as required. It certainly shouldn't hang. It would be better if it displayed an error message. But it also doesn't seem like a problem in any reasonable calculation for which the arguments to CP are properly defined.

What is it you're trying to do?