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MathGroup Archive 2002

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Re: PatternMatching with Dt[]

  • To: mathgroup at smc.vnet.net
  • Subject: [mg37294] Re: [mg37264] PatternMatching with Dt[]
  • From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
  • Date: Tue, 22 Oct 2002 04:47:17 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

The correct function to use is (as the name suggests) HoldPattern:

In[76]:=
Dt[x]/.HoldPattern[Dt[arg_]]:>f[arg]


Out[76]=
f[x]

Andrzej Kozlowski
Yokohama, Japan
http://www.mimuw.edu.pl/~akoz/
http://platon.c.u-tokyo.ac.jp/andrzej/


On Monday, October 21, 2002, at 03:29 PM, Johannes Ludsteck wrote:

> I would like to replace Dt[x_] in a complex
> expression. For example consider
>
> Dt[x]/.Dt[arg_]->f[arg]
>
> where x is a pure Symbol (has no value).
> However, Mathematica refuses apply the rule.
> Various other attempts, for example
> Unevaluted[Dt[arg_]]:>f[arg]
> and HoldForm[...] were unsuccessful.
>
> I managed to  circumvent the problem by
> Dt[x]/.Dt->fun
> However, I were more happy if I understood why the
> first attempt was not successful.
> Can someone explain?
>
> Best regards,
> 	Johannes Ludsteck
> <><><><><><><><><><><><>
> Johannes Ludsteck
> Economics Department
> University of Regensburg
> Universitaetsstrasse 31
> 93053 Regensburg
> Phone +49/0941/943-2741
>
>
>
>



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