Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
1993
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 1993

[Date Index] [Thread Index] [Author Index]

Search the Archive

pure function puzzle

  • To: mathgroup at yoda.physics.unc.edu
  • Subject: pure function puzzle
  • From: wmm at chem.wayne.edu (Martin McClain)
  • Date: Fri, 9 Jul 93 17:37:23 EDT

Dear MathGroupers:
I need a pure function that operates on 

        {x,{a,b,c}}, 

where x, a, b, and c are all simple lists.  The output must be 

        {Ints[x,a],Ints[x,b],Ints[x,c]}, 

where Ints means Intersection.  You would think this could be based on
Thread, but when a,b,c,and x are all lists, Thread seems to get confused. 
Map also has a problem: it needs a function as its argument, and apparently
nested pure functions are not allowed.  I can do the required
transformation with a compound statement

f1 = Intersection[x,#]&;
f2 = Map[f1,#]&

and then apply f2 to my input, but x is not known ahead of time.  I want
this function as one step in a long Composition, and I really need a clean,
single function of a single argument, producing a single object. Maybe some
clever use of Hold, or Evaluate, or something like that ???  Any ideas?






  • Prev by Date: EdgeForm in ListSurfacePlot3D and ParametricPlot3D
  • Next by Date: computer systems
  • Previous by thread: EdgeForm in ListSurfacePlot3D and ParametricPlot3D
  • Next by thread: Re: pure function puzzle