negative integer exponents in polynomials

Hi,

I'm new to axiom, which so far seems great.

How do I get axiom to display polynomials with negative integer exponents, like

--> a + b * z^-1 + c * z^-2 

(DSP style). See below for a transcript. 

(I am using axiom on my Intel macbook 10.5 (I got sbcl and texmacs from macports, and I compiled frimacs using sbcl.  I made a soft link between /usr/local/bin/axiom and AXIOMsys, to get texmacs to work)

Thanks,

Perrin Meyer

→ f := a*z^2 + b*z + c 
→  
a z2 + b z + c
(1)
Type: Polynomial Integer
→ f / z^2 
→  
a z2 + b z + c 
z2 
(2)
Type: Fraction Polynomial Integer
→ % :: UP(z,?) 
→  
a 
z2 z 2 +b 
z2 z +c 
z2 
(3)
Type: UnivariatePolynomial(z,Fraction Polynomial Integer)
→