why is this happening?

American Citizen <[email protected]> Fri, 1 May 2026 17:22:12 -0700

Newsgroups	gmane.comp.mathematics.pari.user
Message-ID	<[email protected]>

? Vecsmall([1]) - Vecsmall([1])
   ***   at top-level: Vecsmall([1])-Vecsmall([1])
   ***                              ^--------------
   *** _-_: forbidden addition t_VECSMALL + t_VECSMALL.
   ***   Break loop: type 'break' to go back to GP prompt
break>

Can anyone explain why this won't work?

Can't we subtract any element in GP Pari from itself and get 0 or null ?