Re: Big problem in solving radicals.
- To: mathgroup at smc.vnet.net
- Subject: [mg41916] Re: Big problem in solving radicals.
- From: davide at astromeccanica.it (Davide Del Vento)
- Date: Tue, 10 Jun 2003 04:46:49 -0400 (EDT)
- References: <bbi16p$7c1$1@smc.vnet.net> <bbkq1p$hi5$1@smc.vnet.net> <bbnb0k$2f0$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hello all!
Paul Abbott <paul at physics.uwa.edu.au> wrote in message news:<bbnb0k$2f0$1 at smc.vnet.net>...
> In article <bbkq1p$hi5$1 at smc.vnet.net>,
> Jens-Peer Kuska <kuska at informatik.uni-leipzig.de> wrote:
>
> > {{x -> a^2}}
> >
> > *is* the general solution, nobody say that x (or a)
> > must be real.
> >
> > There is no way to ask Mathematica for only a real
> > solution in symbolic expressions.
>
> What about
>
> Experimental`CylindricalAlgebraicDecomposition[x^(1/2) + a == 0, {a,x}]
>
> a <= 0 && x == a^2
>
> Cheers,
> Paul
Thank you and thanks to all the others too for your answers.
I think that my original post wasn't clear as it should, because you
are the only one that proposed exactely what I need, while the other
are talking about different (an unimportant) aspect of the problems.
Although "CylindricalAlgebraicDecomposition" works well also with many
variables (e.g. try with a/(b+sqrt(c/x)) == F), it seems to block for
my original problem, but I'm working with it. Keep in mind that
"CylindricalAlgebraicDecomposition" is much more than what I need,
that is a solution as can be simply obtained by Solve and the range of
parameters where it is valid (see my answer to Andrzej Kozlowski too)
Bye,
;Davide Del Vento
CNR Istituto Fisica Spazio Interplanetario
via del Fosso del Cavaliere, 100 / IT-00133 / Rome
Phone: +390649934357
Fax: +390649934383
Mobile: +393288329015
E-Mail: davide @ astromeccanica.it
E-Mail: del vento @ ifsi . rm . cnr . it