Karim BELABAS on Wed, 7 Aug 2002 03:20:00 +0200 (MEST) |
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Re: rnfkummer-induced bug |
On Sun, 4 Aug 2002, Igor Schein wrote: > ? setrand(1);rnfkummer(bnrinit(bnfinit(quadpoly(-8,y)),11,1),[5,2;0,1]); > *** impossible inverse modulo: Mod(0, 11). It's gone now [typo]. 1) I've axed further useless (and quite complicated) code in kummer.c, so that rnfkummersimple (ell-th root of 1 already in K) re-uses the general code (which had become much more efficient). The changes are non trivial so I may have broken something in rnfkummersimple in the process. 2) rnfkummer(bnr, , deg) [output all extensions of degree deg] didn't work in the general case (it was only implemented in rnfkummersimple). It does work in general now. In any case, the documentation was quite misleading: what this variant does is to output all extension _of exact conductor f_ ( assuming bnr = bnrinit(bnf, f, 1) ). _Not_ all extensions included in the ray class field mod f. Changing that behaviour to conform to the docs is rather tedious [I can loop over divisors of the initial conductor, but that would be highly inefficient]. I'd rather fix the documentation so that it corresponds to the current code [ which is entirely trivial: it amounts to skipping the last test = computation of the Artin norm group ] Karim. -- Karim Belabas Tel: (+33) (0)1 69 15 57 48 Dép. de Mathematiques, Bat. 425 Fax: (+33) (0)1 69 15 60 19 Université Paris-Sud Email: Karim.Belabas@math.u-psud.fr F-91405 Orsay (France) http://www.math.u-psud.fr/~belabas/ -- PARI/GP Home Page: http://www.parigp-home.de/