Re: bnfcertify: missing units in bnf

[Karim Belabas <Karim.Belabas@math.u-bordeaux.fr>]

* Karim Belabas [2014-01-30 16:16]:
> * Bill Allombert [2014-01-30 16:05]:
> > On Thu, Jan 30, 2014 at 04:58:13PM +0200, Georgi Guninski wrote:
> > > 2.5.5 on linux x86_64
> > > 
> > > K=bnfinit(x^3+2^2^3+1);bnfcertify(K)
> > > 
> > >  *** bnfcertify: missing units in bnf.
> > 
> > bnfcertify requires the fundamental units to be computed.
> > Use the flags 1 to bnfinit to force their computation:
> > K=bnfinit(x^3+2^2^3+1,1);bnfcertify(K)
> > %1=1
> > 
> > See the documentation:
> > 
> > ? ?bnfinit
> > bnfinit(P,{flag=0},{tech=[]}): compute the necessary data for future
> > use in ideal and unit group computations, including fundamental units
> > if they are not too large. flag and tech are both optional. flag can
> > be any of 0: default, 1: insist on having fundamental units. 
> 
> The documentation of bnfcertify should clearly specify this (and include
> an example). I'll fix it.

Also note that bnfcertify(K,1) does not require units [ it certifies that
the true class group is a quotient of the computed one ]. 

Since in your case, K.clgp is already the trivial group, bnfcertify(K,1)
certifies everything there is to certify about K (which does not include
units :-).

Cheers,

    K.B.
--
Karim Belabas, IMB (UMR 5251)  Tel: (+33) (0)5 40 00 26 17
Universite Bordeaux 1          Fax: (+33) (0)5 40 00 69 50
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