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Re: Strange ReplaceAll behavior

  • To: mathgroup at smc.vnet.net
  • Subject: [mg36794] Re: Strange ReplaceAll behavior
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Thu, 26 Sep 2002 04:56:46 -0400 (EDT)
  • Organization: Universitaet Leipzig
  • References: <amriq5$53u$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

because te right hand side of SetDelayed[] is not
evaluate.

Try

ru[a] = a -> x;
f[x_] := (a + b) /. ru[a];
f1[x_] := Evaluate[(a + b) /. ru[a]];

and f1[] does what you expect
In[]:={f[c], f1[c]}
Out[]={b + x, b + c}

Regards
  Jens

"Lawrence A. Walker Jr." wrote:
> 
> Hi,
> 
> For the life of me I am not sure why the following is not working in my
> v. 4.2:
> 
> ru[a]=a->x;
> f[x_]:=(a+b) /. ru[a];
> 
> Why do I get
> f[c] = b+x
> 
> and not
> f[c] = b+c?
> 
> What gives?
> 
> Thanks,
> Lawrence
> 
> --
> Lawrence A. Walker Jr.
> http://www.kingshonor.com


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