Karim BELABAS on Sun, 14 Sep 2003 13:41:19 +0200 (MEST)


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Re: minor regression


On Fri, 12 Sep 2003, Igor Schein wrote:
>           GP/PARI CALCULATOR Version 2.2.7 (development CHANGES-1.804)
>             i686 running linux (ix86/GMP-4.1 kernel) 32-bit version
>        compiled: Sep 11 2003, gcc-3.2 20020903 (Red Hat Linux 8.0 3.2-7)
>                 (readline v4.3 enabled, extended help available)
>
> ? \p86
>    realprecision = 86 significant digits
> ? setrand(1);rnfkummer(bnrinit(bnfinit(y^4-15*y^3+10*y^2-7*y+17,1),1,1),0);
>   ***   precision too low in zsigne.
> ? \p96
>    realprecision = 96 significant digits
> ? setrand(1);rnfkummer(bnrinit(bnfinit(y^4-15*y^3+10*y^2-7*y+17,1),1,1),0);
> ?
>
> Before it would work at \p28.

I (recently) replaced a wrong bound by a heuristic one , which happens to be
wrong in this example.
[ It's a lower bound for the absolute values of a non-zero algebraic integer,
used to check whether input precision is sufficient before starting to
compute signatures ].

Since most of the time is spent elsewhere, I've replaced it by a safe bound
instead.

Fixed in CVS.

    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              http://www.math.u-psud.fr/~belabas/
F-91405 Orsay (France)            http://www.parigp-home.de/  [PARI/GP]