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. >