Function: rnfdisc
Section: number_fields
C-Name: rnfdiscf
Prototype: GG
Help: rnfdisc(nf,pol): given a pol with coefficients in nf, gives a
 2-component vector [D,d], where D is the relative ideal discriminant, and d
 is the relative discriminant in nf^*/nf*^2.
Doc: given a number field $\var{nf}$ as
 output by \kbd{nfinit} and a polynomial \var{pol} with coefficients in
 $\var{nf}$ defining a relative extension $L$ of $\var{nf}$, computes the
 relative discriminant of $L$. This is a two-element row vector $[D,d]$, where
 $D$ is the relative ideal discriminant and $d$ is the relative discriminant
 considered as an element of $\var{nf}^*/{\var{nf}^*}^2$. The main variable of
 $\var{nf}$ \emph{must} be of lower priority than that of \var{pol}, see
 \secref{se:priority}.
