Re: How recovering the b in Mod(a,b)?

[Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>]

On Wed, Oct 10, 2007 at 11:53:28PM +0200, mehnert@math.uni-sb.de wrote:
> 
> Hello dear Pari/GP users,
> 
> I have a may be very simple Problem. If I know x = Mod(a,b), then with "lift" I
> can recover a, but how do I recover b? Thank you for any Answer.

Use x.mod:
? Mod(1,4).mod
%1 = 4
? Mod(1,x^2+1).mod
%2 = x^2 + 1

You could also use component(x,1):
? component(Mod(1,4),1)
%3 = 4
? component(Mod(1,x^2+1),1)
%4 = x^2 + 1

Cheers,
Bill.