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Re: Slots & Ampersands

  • To: mathgroup at smc.vnet.net
  • Subject: [mg74407] Re: [mg74359] Slots & Ampersands
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Tue, 20 Mar 2007 05:50:27 -0500 (EST)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200703191053.FAA27902@smc.vnet.net>
  • Reply-to: murray at math.umass.edu

"RGBColor[1, 0, 0]" designates a constant, not a function.  By contrast, 
"RGBColor[1, 0, 0]&" designates a function -- an abbreviation for

   Function[x, RGBColor[1, 0, 0]]

or even just for

   Function[RGBColor[1, 0, 0]].

This is the way to form an anonymous (i.e., no-name) constant function.


Mr Ajit Sen wrote:
>   Dear MathGroup,
> 
>  I've always regarded the Slot and Ampersand as being
>  inseparable in Mathematica (the Laurel & Hardy of 
>  Mathematica?), and was surprised to find one of them absent
> in
> 
>    Plot[Sin[x], {x, 0, 2Pi}, ColorOutput -> 
>       (RGBColor[1, 0, 0]&)]
> 
>  [Help Browser under ColorOutput::colpc ,Examples]
> 
>   Question 1
> 
>   Where is Laurel gone? Is he inside ColorOutput or
>   RGBColor?
> 
>   Question 2
> 
>   Are there other similar constructs in Mathematica? [No # ]
> 
>   Thanks for your help.
> 
>   Ajit Sen.
> 
> 
> 
> 
> 		
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-- 
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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