Re: About Reduce and domains
- To: mathgroup at smc.vnet.net
- Subject: [mg98662] Re: About Reduce and domains
- From: dh <dh at metrohm.com>
- Date: Thu, 16 Apr 2009 04:10:39 -0400 (EDT)
- References: <grupt9$s5$1@smc.vnet.net>
Hi,
if you want something like x>0... then you specify a domain implicitly.
For a complex number x>0 does not make much sense.
Note that you may also specify the domain of some variables in the first
argument of Reduce:
Reduce[{..,Element[{x,y},Reals],..}]
Daniel
olfa wrote:
> Hi Mathematica community,
>
>
> I remarqued in many outputs with reduce, that mathematica treats some
> parameters as complexe numbers and consequently distinguich between Re
> part and Im part:
> For example:
> (Re[d]<0&&Re[a]<0&& ...) || (Re[d]<0&&Re[a]==0&&Im[a]<0&& ...) || (Re
> [d]<0&&Re[a]==0&&Im[a]>0&&...) || (Re[d]<0&&Re[a]>0&&...) || (Re[d]
> ==0&&Im[d]<0&&Re[a]<0&&...) ||...
>
> In the help I have read that Reduce[expr,vars] assumes by default that
> quantities appearing algebraically in inequalities are real, while all
> other quantities are complex.
>
> But is there a mean to force mathematica in the way that it does not
> distinguich between real part and imaginary part in the output and
> consequently to have: d<0 && a<0 ...|| d==0 && a>0 || ...without
> specifying a domain which means without Reduce[expr,vars,doms]?
>
>
>
> Thank you very much.
>