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

*To*: mathgroup at smc.vnet.net*Subject*: [mg121914] Re: can't find info about & /@ %*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Thu, 6 Oct 2011 04:24:43 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201110050759.DAA06921@smc.vnet.net>*Reply-to*: murray at math.umass.edu

Didn't you try searching for any of those symbols in the Documentation Center? For example, searching for /@ brings up a single search result, for Map, and if you go to the reference page for Map you'll see what it does and that /@ is a "special input form" -- a shortcut -- for using Map. Similarly for the others. In any case, here's the explanation: (1) [Options[#, "ColorSpace"]& is a "pure function" -- a function with no name -- as the trailing "&" indicates. It takes a single argument, which gets stuck into where the "Slot" symbol # is. (2) % is another shortcut, standing for the preceding output. Presumably here that preceding output was a list of some kind. (3) fn /@ lis, a shortcut for Map[fn, lis] evaluates the function fn at each member of the list lis and assembles all the results back into a list. (Map is actually more general than that.) Hope this helps. On 10/5/11 3:59 AM, Richard Cohen wrote: > First[Options[#, "ColorSpace"]& /@ %] > could someone please explain the use of these& /@ % > i've looked everywhere to no avail. > rich > -- 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

**References**:**can't find info about & /@ %***From:*Richard Cohen <cohenrich@gmail.com>