Re: why is this happening?

[Loïc Grenié <loic.grenie@gmail.com>]

On Sat 2 May, 2026, at 02:31, American Citizen wrote:

? 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 ?

     You cannot add/subtract two vecsmalls, because the sum/difference of

  two (short) integers of 64 bits (32 on 32 bit platforms) can easily overrun

  64 bits. If you just want to know whether the 2 vecsmalls are equal, you

  can use ==.

     Hope this helps,

         Loïc