nf = nfinit(polsubcyclo(11,5));
t = nf.zk[2];
nfeltsign(nf, t)
nfeltsign(nf, t, 1)
nfeltsign(nf, t, [1..4])
nfeltsign(nf, [1,0,0,0,0]~, [1..4])
nfeltsign(nf, [-1/2,0,0,0,0]~, [1..4])
nfeltsign(nf, 0, 1)

nfeltsign(nf, x+950385237198502187979577282097391163977102921506573742575513/495253880608585631635195731645995689515566957889181807495428)


nf=nfinit(a^2-2);
for(n=1,100,if(nfeltsign(nf,Mod(a+1,a^2-2)^n)!=[(-1)^n,1],print(n)))

\\ Errors
nfeltsign(nf, a, 3)
nfeltsign(nf, a, [-1..1])
nfeltsign(nf, a, [1..3])
