Function: rnfidealnormrel
Section: number_fields
C-Name: rnfidealnormrel
Prototype: GG
Help: rnfidealnormrel(rnf,x): relative norm of the ideal x.
Doc: let $\var{rnf}$ be a relative
number field extension $L/K$ as output by \kbd{rnfinit} and let $x$ be a
relative ideal (which can be, as in the absolute case, of many different
types, including of course elements). This function computes the relative
norm of $x$ as an ideal of $K$ in HNF.