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Re: Problem with ->



Hi,

what you are doing wrong is the following: You define a value for R[s]
(the same as writing  R[s] = k s) instead of defining a function like
R[s_] := k s. 

So if you do not like definig R[s_] := k s  and then evaluating your
expression, you definitely have to write:

R[s]/ R'[s] /. R->Function[x, k x]

getting  s  as the result.
(you could even write s instead of x above, but I tried to avoid
confusion...)

Hope I could help
Clemens

------------------------------------------------------------------
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
> 
> What am I doing wrong?
> 
> Hans Friedrich Steffani
> --
> Hans Friedrich Steffani
> Institut fuer Elektrische Maschinen und Antriebe, TU Chemnitz
> mailto:hans.steffani@e-technik.tu-chemnitz.de
> http://www.tu-chemnitz.de/~hfst/



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