algsys with realonly:true, was: error in solving x^4> -2 via solve_rat_ineq
Subject: algsys with realonly:true, was: error in solving x^4> -2 via solve_rat_ineq
From: Volker van Nek
Date: Fri, 22 Jan 2010 20:44:04 +0100
Robert,
I just have noticed, that this is a known bug: 2786017 (2009-05-03)
Volker van Nek
Am Freitag, den 22.01.2010, 17:46 +0100 schrieb Volker van Nek:
> Hi Robert,
>
> right, this is a bug. But it's an algsys bug.
> solve_rat_ineq uses algsys with the flag realonly:true to cut off all
> complex solutions.
>
> (%i2) algsys([x^4=-2],[x]), realonly:true;
> (%o2) [[x = (-1)^(1/4)*2^(1/4)],[x = -(-1)^(1/4)*2^(1/4)]]
>
> In this case algsys shouldn't return a non-real solution. Or do I
> misunderstand the usage of realonly?
>
> Please file a bug report concerning algsys using realonly:true.
>
> Volker van Nek
>
>
> Am Freitag, den 22.01.2010, 14:55 +0000 schrieb Robert Marik:
> > Dear all,
> >
> > I observed the following bug when trying to work with solve_rat_ineq. I think it
> > is a bug (complex numbers do not form ordered set) and the answer should be 'all'
> >
> > sage: maxima("(load(\"solve_rat_ineq.mac\"),solve_rat_ineq(x^4>-2))")
> > [[x>-(-1)^(1/4)*2^(1/4),x<(-1)^(1/4)*2^(1/4)]]
> >
> > Robert
> >
> >
> >
> > _______________________________________________
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>
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