Re: bnfisintnorm(bnfinit(x^2+3),7^5) misses integral solution

Bill Allombert <[email protected]>
Newsgroups gmane.comp.mathematics.pari.devel
Message-ID <20201118124931.GC5556@yellowpig>
On Wed, Nov 18, 2020 at 02:22:47PM +0200, Georgi Guninski wrote:
> bnfisintnorm() appears to miss integral solutions, is this
> expected?
> 
> ? bnfisintnorm(bnfinit(x^2+3),7^5)
> %25 = [-149/2*x - 25/2, 133/2*x + 119/2, -147/2*x + 49/2, 147/2*x +
> 49/2, -133/2*x + 119/2, 149/2*x - 25/2]
> ? norm(Mod(2+x,x^2+3)^5)-7^5
> %26 = 0
> ? Mod(2+x,x^2+3)^5
> %27 = Mod(-31*x - 118, x^2 + 3)

Hello Georgi,

Note that the documentation says "modulo units of positive norm".
Let u the third root of unity:
? u=Mod(-1/2*x+1/2,x^2+3);
? norm(u)
%2 = 1
? (-149/2*x - 25/2)*u
%3 = Mod(-31*x-118,x^2+3)

So the list is complete modulo units of positive norm.
Cheers,
Bill.
lmpx.com only provides a reader for public news (NNTP) servers. It is not affiliated with the servers or forums shown here and is not responsible for the content of articles, which is written by their respective authors.