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Re: can't find info about & /@ %

  • To: mathgroup at smc.vnet.net
  • Subject: [mg121911] Re: can't find info about & /@ %
  • From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
  • Date: Thu, 6 Oct 2011 04:24:06 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <j6h31i$6un$1@smc.vnet.net>

Hi Richard,

These are actually three operators:

& (Function) is part of a pure function expression: e.g. #^2& is a
function that squares it argument; # stands for the argument

/@ is the infix form of the Map function, which can be used to map a
function over a list of items

% (Out) is the shorthand notation for the result returned in the most
recent evaluation (presumably in this case the evaluation returned a
list of items)

How could you have found out this yourself? Well,

- select the '&', press F1 (Help on Windows) and the second item is
'Function'
- select /@, press F1 and the only result is 'Map'
- select '%', press F1 and the second result is `Out`

It's actually not that difficult.

Cheers -- Sjoerd


On Oct 5, 10:04 am, Richard Cohen <cohenr... at gmail.com> wrote:
> First[Options[#, "ColorSpace"] & /@ %]
> could someone please explain the use of these  & /@ %
> i've looked everywhere to no avail.
> rich




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