Function: bnrinit
Section: number_fields
C-Name: bnrinit0
Prototype: GGD0,L,
Help: bnrinit(bnf,ideal,{flag=0}): given a big number field as output by
 bnfinit (only) and an ideal or a 2-component row vector formed by an ideal
 and a list of R1 zeros or ones representing a module, initializes data
 linked to the ray class group structure corresponding to this module. flag
 is optional, and can be 0: default (same as bnrclass with flag = 1), 1:
 compute also the generators (same as bnrclass with flag = 2). The fifth
 component is the ray class group structure
Description:
 (gen,gen,?small):bnr       bnrinit0($1, $2, $3)

