Re: Problem with ->
- To: mathgroup@smc.vnet.net
- Subject: [mg11520] Re: Problem with ->
- From: Paul Abbott <paul@physics.uwa.edu.au>
- Date: Fri, 13 Mar 1998 12:22:09 -0500
- Organization: University of Western Australia
- References: <6dv2lm$5dl@smc.vnet.net>
Hans Steffani wrote:
> I want to substitute R[s] by k s.
> I tried:
> R[s] / R'[s] /. R[s] -> k s
> and got
> k s / R'[s]
> instead of the expected
> s
Another solution, avoiding pure functions, and working for derivatives
to any order, is to use pattern-matching:
In[1]:= R[s]/R'[s]/.{R[s] -> k s,
Derivative[n_][R][s] :> D[k s, {s, n}]}
Out[1]= s
Cheers,
Paul
____________________________________________________________________
Paul Abbott Phone: +61-8-9380-2734
Department of Physics Fax: +61-8-9380-1014
The University of Western Australia Nedlands WA 6907
mailto:paul@physics.uwa.edu.au AUSTRALIA
http://www.pd.uwa.edu.au/~paul
God IS a weakly left-handed dice player
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