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Re: Giving several functions the same argument

  • To: mathgroup at smc.vnet.net
  • Subject: [mg109625] Re: Giving several functions the same argument
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Sat, 8 May 2010 07:08:54 -0400 (EDT)

Use Through.  E.g.:

   Through[{Sin, Cos}[Pi]]
{0, -1}

   f = (2 # &); g = (#^2 &);
   Through[{f, g}[3]]
{6, 9}

On 5/7/2010 6:28 AM, Simon Pearce wrote:
> Hi Mathgroup,
>
>
>
> I have a list of pure functions, which I wish to apply to the same
> argument. I can't seem to be able to thread the list of functions over
> the argument in a simple way, all the commands like Apply and Map etc
> take a single function. I can do it using Table and Part, but it seemed
> like there should be a simple command that I'm missing.
>
>
>
> For example:
>
>
>
> In[1]:= functs = {Sin[#1]&, Cos[#1]&};
>
>
>
> In[2]:= functs[x]
>
>
>
> Out[2]= {Sin[#1]&, Cos[#1]&}[x]
>
>
>
> I want to get the result {Sin[x],Cos[x]} out, without having to use
> something of the form:
>
>
>
> In[3]:= Table[functs[[i]][x], {i, 1, 2}]
>
>
>
> Out[3]= {Sin[x], Cos[x]}
>
>
>
> Which seems like it'd be less efficient when I try and use it on long
> lists of functions.
>
>
>
> Thanks,
>
> Simon
>

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


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