Re: nffactor() regression

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

On Tue, 18 Jun 2002, Karim BELABAS wrote:

> ? nffactor(nfinit(polsubcyclo(17,8,y)),x^48-104*x^46+4664*x^44-122476*x^42+2137838*x^40-26567700*x^38+245144964*x^36-1725955872*x^34+9441692003*x^32-40611588 644*x^30+138356971048*x^28-374714866240*x^26+807289826646*x^24-1380693858220*x^22+1866021172640*x^20-1978766780068*x^18+1630151673857*x^16-1029505301024*x^14 +489498952012*x^12-170832297056*x^10+42133382284*x^8-6904507136*x^6+669868016*x^4-28899680*x^2+16)
>   ***   bug in LLL_cmbf [no factor], please report

OK, removing 0 columns in LLL_check_progress() was not the brightest thing to
do (even though the projected lattice remains the same, we may lose small
vectors in the original lattice).

But I notice I had forgotten to impose a minimal precision when truncating
entries in van Hoeij's lattice [ this is already enforced over Z ]. And I had
not tested this code with so few modular factors.

Imposing at least 32 bits of precision (might be overkill) fixes this
problem, as well as the original one.

    Karim.
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Karim Belabas                    Tel: (+33) (0)1 69 15 57 48
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Université Paris-Sud             Email: Karim.Belabas@math.u-psud.fr
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