Karim BELABAS on Wed, 4 Dec 2002 22:27:15 +0100 (MET) |
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Re: regression in ZX_resultant_all() |
On Wed, 4 Dec 2002, Igor Schein wrote: > it can be reproduced by the following: > > ? polgalois(subst(x^8-n*x^6+(2*n+14)*x^4-n*x^2+1,n,600!)) > [40320, -1, 50] > > It stopped working Nov 6, 2002. ZX_resultant_all() returns a number > which is not a square, and galoisbig() thinks the group is ODD. Precision error [ the algebraic resultant bound is huge: we compute a floating point approximation to the resultant, and it turns out to be 0.E4000, with no digit of accuracy left ]. It should be fixed now. Karim. -- Karim Belabas Tel: (+33) (0)1 69 15 57 48 Dép. de Mathématiques, Bât. 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/