Re: polredabs() bug

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

On Mon, 29 Jul 2002, Igor Schein wrote:
> polredabs() doesn't reduce the following polynomial:
>
> x^8-2*x^7-34*x^6+78*x^5+265*x^4-628*x^3-389*x^2+1237*x-449
>
> The correct answer is
>
> x^8-2*x^7-22*x^6+46*x^5+73*x^4-102*x^3-19*x^2+25*x+5
>
> as returned by version 2.0.19 and earlier.

A typo in chk_gen_init, when computing the 'skipfirst' parameter [ the first
'skipfirst' elements of the integer basis generate a strict subfield, which
is used to prune the search tree ]. The field of largest degree returned by
polcompositum is the last one, not the first one.

Fixed.

    Karim.
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Karim Belabas                    Tel: (+33) (0)1 69 15 57 48
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