In a fresh Maxima, 'between' has no properties (check :lisp (mapcar 'symbol-plist '($between %between)) and integrate(x^2*between(x,a,b,'closed),x); causes no errors. So presumably the problem is in your pw code. On Thu, Apr 8, 2010 at 23:45, Richard Hennessy <rich.hennessy at verizon.net>wrote: > >