Re: polresultant disagrees with sage, maxima and magma

[Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>]

On Thu, Sep 20, 2012 at 03:19:52PM +0100, John Cremona wrote:
> 
> I don't think this is a good enough answer (sorry, Bill!).    I know
> that there are reasons for pari's variable priorities, and I have
> personally been entertained by hem for many years,  but  if
> "polresultant(p1,p2,x1)" is to correspond to any mathematically
> correct resultant function then it has to be independent of that
> (invisible) priority.

I agree with you, I was just pointing out the discrepancy!

On Thu, Sep 20, 2012 at 05:05:25PM +0200, Karim Belabas wrote:
> It should have worked, and this was a bug in PARI. All such examples should be
> fixed in master HEAD after the following commit:
> 
>   commit 7079c4f7813c582949dea92a3089bf6a6c532738
>   Author: Karim Belabas <Karim.Belabas@math.u-bordeaux1.fr>
>   Date:   Thu Sep 20 16:23:33 2012 +0200
> 
>       fix: resultant(x,x,y) -> 0 and related problems
> 
>       Original bug report:
>         p1=x2*(x3-x4);p2=x2*(x3-2*x4);polresultant(p1,p2,x1) -> 0. Should be 1

Should I backport it to pari 2.5.3 ?

Cheers,
Bill.