Function: bnfcertify
Section: number_fields
C-Name: bnfcertify0
Prototype: lGD0,L,
Help: bnfcertify(bnf,{flag = 0}): certify the correctness (i.e. remove the GRH) of the bnf data output by bnfinit. If flag is present, only certify that the class group is a quotient of the one computed in bnf (much simpler in general).
Doc: $\var{bnf}$ being as output by
 \kbd{bnfinit}, checks whether the result is correct, i.e.~whether it is
 possible to remove the assumption of the Generalized Riemann
 Hypothesis\sidx{GRH}. It is correct if and only if the answer is 1. If it is
 incorrect, the program may output some error message, or loop indefinitely.
 You can check its progress by increasing the debug level.

 If flag is present, only certify that the class group is a quotient of the
 one computed in bnf (much simpler in general).
Variant: Also available is  \fun{GEN}{bnfcertify}{GEN bnf} ($\fl=0$).
