Re: polredabs failure

[Igor Schein <igor@txc.com>]

On Thu, Oct 09, 2003 at 09:04:42PM +0200, Karim BELABAS wrote:
> On Thu, 9 Oct 2003, Igor Schein wrote:
> > ? p1=x^16-4*x^15-20*x^14+80*x^13+138*x^12-712*x^11+736*x^10+1200*x^9-8138*x^8+9288*x^7+1904*x^6-25248*x^5+73988*x^4-19184*x^3+41192*x^2+69456*x+30724;
> > ? p2=x^16 + 66*x^12 + 3627*x^8 + 48114*x^4 + 531441;
> > ? p1==polredabs(p1)
> > 1
> > \\ p1 already *reduced*
> > ? poldegree((v=polcompositum(p1,p2))[#v])
> > 16
> > \\ isomorphic
> > ? norml2(polroots(p1))
> > 91.81780460041328907655758261
> > ? norml2(polroots(p2))
> > 87.63560920082657815311516524
> > \\ so we should have polredabs(p1)==p2
> 
> A complicated typo. The smallest element was found, then deleted due to a typo
> which assessed to it the norm of another (larger) element, during the
> "Sorting" phase (when there are too many small vectors, the list overflows,
> and we need to discard some of them). Fixed in CVS.

Immediate regression:

? allocatemem()
  ***   Warning: doubling stack size; new stack = 8000000 (7.629 Mbytes).
? polredabs(x^16-4*x^15+16*x^13-48*x^11+16*x^10-32*x^9+360*x^8-616*x^7+352*x^6-112*x^3+96*x^2-32*x+4)
  ***   bug in GP (Segmentation Fault), please report

Thanks

Igor