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MathGroup Archive 2005

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Re: Free variables in an expression

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54791] Re: Free variables in an expression
  • From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
  • Date: Wed, 2 Mar 2005 01:26:38 -0500 (EST)
  • Organization: Uni Leipzig
  • References: <d0142d$oon$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

what is a "free (unbound)" variable.
a) ?ValueQ
ValueQ[expr] gives True if a value has been defined for expr, and gives 
False \
otherwise.

b) without Hold[] you will never see the variables that have values because 
Mathematica will evaluate the expression until all variables with a value 
are replaced by the values



Regards

  Jens



"Sascha Kratky" <notvalid at notvalid.com> schrieb im Newsbeitrag 
news:d0142d$oon$1 at smc.vnet.net...
> Is there a Mathematica built-in function that gives a list of free
> (unbound) variables in an arbitrary expression?
>
> Thanks,
> Sascha
> 



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