[Maxima] tellsimp and limit

[Richard Hennessy]

I have tried to coax Maxima to be able to compute the limit(signum(x),x,0,minus)=-1 and limit(signum(x),x,0,plus)=1

I did this.


(%i1) matchdeclare(aa,constantp,xx,true);
(%o1) done
(%i2) tellsimp(limit(signum(xx),xx,0,minus),-1);
(%o2) [limitrule1,false]
(%i3) remove([aa,xx],matchdeclare);
(%o3) done
(%i4) limit(signum(x),x,0,minus);
(%o4) limit(signum(x),x,0,minus)

You just get the noun form.  The same thing happens with tellsimpafter.  The signum case is giving me headaches.  Does anyone have 
any ideas?  Should this be possible to do this?

Rich