Function: nfdisc
Section: number_fields
C-Name: nfdisc0
Prototype: GD0,L,DG
Help: nfdisc(x,{flag=0},{fa}): discriminant of the number field defined by
 the polynomial x using round 4. Optional args flag and fa are as in nfbasis.
Doc: \idx{field discriminant} of the number field defined by the integral,
 preferably monic, irreducible polynomial $x$. $\fl$ and $fa$ are exactly as
 in \kbd{nfbasis}. That is, $fa$ provides the matrix of a partial
 factorization of the discriminant of $x$, and binary digits of $\fl$ are as
 follows:

 1: assume that no square of a prime greater than \kbd{primelimit}
 divides the discriminant.

 2: use the round 2 algorithm, instead of the default \idx{round 4}. This
 should be slower except maybe for polynomials of small degree and
 coefficients.
Variant: Also available is \fun{GEN}{nfdisc}{GEN x} ($\fl=0$).
