Karim BELABAS on Wed, 11 Sep 2002 02:30:13 +0200 (MEST) |
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Re: bnfisnorm() broken again |
On Tue, 10 Sep 2002, Igor Schein wrote: > ? rnfisnorm(rnfisnorminit(y^2 + 29*y + 21,x^3 - 10*x^2 - 3*x - 5),2) > *** precision too low in isunit. > > Looks like internal precision is used to compute units Not really. I've slightly modified the logic to jump quickly to the "right" precision instead of doubling a few times before giving up. Is is better ? It's now a bug that such large units enter the picture. The extension field simply has large fundamental units (see T[2].fu, with T the rnfisnorminit) > and user cannot influence it. Yes you could. But it should have been about \p2000 or higher to stand a chance. > Also, I can't figure out which flags to use to speed up rnfisnorminit() in > the example above. It's not slow, it takes a few seconds! The algorithm requires computing the bnfinit() of the absolute extension, which may be very expensive. 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/