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 17:46:07 +0100
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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