Function: nfeltadd
Section: number_fields
C-Name: nfadd
Prototype: GGG
Help: nfeltadd(nf,x,y): element x+y in nf.
Doc:
 given two elements $x$ and $y$ in
 \var{nf}, computes their sum $x+y$ in the number field $\var{nf}$.
