Re: polredabs() observation

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

On Tue, 4 Feb 2003, Igor Schein wrote:
> It's still pretty much broken.  Consider the following trivial cases:
>
> polredabs(x^4+10^80*x^2+1,16)
>
> precision issue, takes years
>
> polredabs(x^8+10^80*x^4+1,16)
>
> too many vectors, also takes years
>
> Both used to finish in no time.

OK, my fix from yesterday was too optimistic. It assumed that overestimating
the bound by at most 1.e-4% was not a big deal, and we could operate on
machine floats. I was wrong.

In your examples above, you quickly get 1e40 more vectors in this way [and
much larger bounds than expected due to catastrophic cancellation...]

Better now?

    Karim.
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