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MathGroup Archive 1998

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Re: (a-b)/(c-d)=!=(b-a)/(d-c) ???

  • To: mathgroup at smc.vnet.net
  • Subject: [mg13018] Re: [mg12964] (a-b)/(c-d)=!=(b-a)/(d-c) ???
  • From: Sean Ross <seanross at worldnet.att.net>
  • Date: Tue, 30 Jun 1998 00:26:15 -0400
  • References: <199806280651.CAA24289@smc.vnet.net.>
  • Sender: owner-wri-mathgroup at wolfram.com

Tim Dellinger wrote:
> 
> How come
> (a-b)/(c-d) === (b-a)/(d-c)
> 
> returns False, i.e. TrueQ[ (a-b)/(c-d) =!= (b-a)/(d-c) ]  returns True,
> 
> but
> 
> (a-b)/(c-d) === Simplify[ (b-a)/(d-c) ]
> 
> returns True ???
> 
> Why does mere simplification change anything? I'm using Mathematica
> 3.0.?  on win95.
> 
> --
> --
> "Perhaps my most deeply rooted hobby is to understand         Tim
> Dellinger
>  the mechanisms of simple and familiar
> tdelling at uiuc.edu
>  natural phenomena." Irving Langmuir
> http://www.ews.uiuc.edu/~tdelling


The SameQ function is more of a pattern matching function rather than a
value matching function.  Since you gave it a symbolic expression, it
tested for absolute identicality, not equivalence.  If you had done
this with Integer or Real expressions, then the Evaluation of the
expression would have done what you wanted.


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