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MathGroup Archive 2000

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Re: getting module output in replace form

  • To: mathgroup at smc.vnet.net
  • Subject: [mg24648] Re: getting module output in replace form
  • From: "Allan Hayes" <hay at haystack.demon.co.uk>
  • Date: Mon, 31 Jul 2000 09:23:19 -0400 (EDT)
  • References: <8lsts5$22u@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Mike,
Please look at the InputForm of your output. It looks as if it will contain
expressions like
0.234*"var1->",
not rules.

How about the following?


CalculateVariables[a_, b_, c_] :=
  Thread[Rule[{var1, var2, var3}, {a b^c, b/c, a - b}]]

CalculateVariables[x, y, z]

        {var1 -> x*y^z, var2 -> y/z, var3 -> x - y}


Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565

"Michael Gilchrist" <mag5 at duke.edu> wrote in message
news:8lsts5$22u at smc.vnet.net...
> Hi,
>
> I am trying to create a module that will output a list of replacement
> rules.
>
> for example
>
> {var1, var2}/.CalculateVariables[1, 0.3, 1.222]
>
> where CalculateVariables is the module I am writing.
>
> i.e.
>
> CalculateVariables[a_, b_, c_]:=
> Module[{var1, var2, var3, var4},
>
> var1 = a* b^c;
> var2 = b/c;
> .
> .
> .
>
> {"var1 ->" OutputForm[var1],
> "var2 ->" OutputForm[var2],
> "var3 ->" OutputForm[var3],
> "var4 ->" OutputForm[var4]
> }
> ]
>
> But if I try to use the output as a replacement rule I get
>
> >ReplaceAll::"reps" {{var1-> 0.234, var2->0.323, var3-> 100001, var4->0}}
> is neither a list of replacement
> rules nor a valid dispatch table, and so cannot be used for replacing."
>
>
>
> I have tried wrapping the "vari ->" in textform, outputform, etc but get
> nowhere.
>
> I feel like I must be doing something wrong since this seems like it
> should be an easy and common use of a module.  Any help would be
> appreciated.
>
> Thanks,
>
>
> Mike
>
>
> Michael Gilchrist
> Dept. of Biology
> Duke University
> Durham, NC 27708
>
>
>
>




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