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Re: Domain of a function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg123260] Re: Domain of a function
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Tue, 29 Nov 2011 07:06:08 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <j9b6lb$4sv$1@smc.vnet.net> <j9lpke$lif$1@smc.vnet.net> <201111270914.EAA07275@smc.vnet.net> <201111281052.FAA19690@smc.vnet.net>

Forgot to mention the obvious:

Reduce[Element[x | Sqrt[2 + x], Reals]]

x >= -2

Andrzej Kozlowski


On 28 Nov 2011, at 11:52, Andrzej Kozlowski wrote:

> 
> On 27 Nov 2011, at 10:14, Tutor wrote:
> 
>> Element[x | Sqrt[2 + x], Reals]; what exactly does "|" in this case?
> 
> The first argument of Element can be a pattern and the assertions is 
> that everything that matches the pattern is real. So what kind things 
> match the pattern? For one, x matches it. Also, Sqrt[2+x] matches it and 
> nothing more does. In other words, both x and Sqrt[2+x] must be real.
> 
> 
> Andrzej Kozlowski
> 




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