MathGroup Archive 1996

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

Search the Archive

addressing matrix elements

  • To: mathgroup at
  • Subject: [mg3566] addressing matrix elements
  • From: drc at (David Cabana)
  • Date: Mon, 25 Mar 1996 21:33:49 -0500
  • Organization: CyberGate, Inc.
  • Sender: owner-wri-mathgroup at

The Mma language sometimes drives me crazy.  If I don't practice it
regularly, I seem to forget everything.  Here's what I want to do, but

Say M is a matrix of integers.  I want to func[M, k] to return a matrix
same dimensions as M, each entry consisting of the corresponding entry of
M taken modulo k.  For instance, func[{{22,33}, {44,55}}, 10] should
return {{2,3}, {4,5}}.  I would like this to work for arbitrary
rectangular integer matrices, but am not having much luck.  It seems like
this should be easy,  but I'm stumped.  

More generally, I would like to be able to apply a function f to each
element in a matrix of arbitrary size and dimensions, without worrying
about the particulars of the matrix representation via lists.  I want
func[M, g] to return a matrix of the same size and shape as M, with
elements formed by applying g to corresponding elements of M.  Is there
nice way to do this?  Seems like some combination  of Map, Apply, Thread,
SetAttributes Listable, Outer, etc. could do the job, but I am lost in the
morass of possibilites.   Any help would be appreciated.


David Cabana    drc at 

"Ask the American public if they want an FBI Wiretap and they'll say 'no.'  If you ask them do they want a feature on their phone that helps the FBI find their missing child they'll say, 'Yes.'"
  - FBI Directory Louis Freeh, on Digital Telephony, US House (Subcmte. on
Telecommunications & Finance) hearing on the Digital Telephony bill, 09/13/94). 

"The people never give up their liberties but under some delusion"
  - Edmund Burke


  • Prev by Date: Re: ListPlot3D
  • Next by Date: awk in mathematica
  • Previous by thread: Re: Coefficient in multivariate series
  • Next by thread: Re: addressing matrix elements