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Re: Through[Divide[f1, f2][x]]

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  • Subject: [mg130954] Re: Through[Divide[f1, f2][x]]
  • From: Ray Koopman <koopman at>
  • Date: Tue, 28 May 2013 04:18:29 -0400 (EDT)
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On Sun, May 26, 2013 @ 11:23 AM, Andrzej Kozlowski <akozlowski at> wrote:
> On 26 May 2013, at 11:06, Ray Koopman <koopman at> wrote:
>> Either of these will give you f1[x]/f2[x]:
>>  Divide@@{f1@#,f2@#}&@x
>>  Divide@@(#@x&)/@{f1,f2}
>> Sometimes it would be nice to have a "reverse map", that 
>> applied each of a list of functions to a single argument, 
>> instead of a single function to each of a list of arguments.
> I am not sure I understand what you mean. Why doesn't Through do that?
> Through[{f, g, h}[x]]
> {f[x], g[x], h[x]}
> Andrzej Kozlowski

Through does do that. When I saw Bob's response to the original post 
I asked myself "How did I miss that?" I thought I had tried it and 
found that it didn't work. The only explanation I can think of is 
that I had the "reverse map" metaphor fixed too firmly in my mind, 
to the point that I used Map-like syntax [{f1,f2},x] instead of 

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