Function: rnfconductor
Section: number_fields
C-Name: rnfconductor
Prototype: GGD0,L,
Help: rnfconductor(bnf,pol): conductor of the Abelian extension
 of bnf defined by pol. The result is [conductor,rayclassgroup,subgroup],
 where conductor is the conductor itself, rayclassgroup the structure of the
 corresponding full ray class group, and subgroup the HNF defining the norm
 group (Artin or Takagi group) on the given generators rayclassgroup[3].
Doc: given $\var{bnf}$
 as output by \kbd{bnfinit}, and \var{pol} a relative polynomial defining an
 \idx{Abelian extension}, computes the class field theory conductor of this
 Abelian extension. The result is a 3-component vector
 $[\var{conductor},\var{rayclgp},\var{subgroup}]$, where \var{conductor} is
 the conductor of the extension given as a 2-component row vector
 $[f_0,f_\infty]$, \var{rayclgp} is the full ray class group corresponding to
 the conductor given as a 3-component vector [h,cyc,gen] as usual for a group,
 and \var{subgroup} is a matrix in HNF defining the subgroup of the ray class
 group on the given generators gen.
