Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2007
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2007

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

Search the Archive

Re: matrices with arbitrary dimensionality

  • To: mathgroup at smc.vnet.net
  • Subject: [mg76703] Re: [mg76640] matrices with arbitrary dimensionality
  • From: Sseziwa Mukasa <mukasa at jeol.com>
  • Date: Sat, 26 May 2007 04:27:42 -0400 (EDT)
  • References: <200705251028.GAA07480@smc.vnet.net>

On May 25, 2007, at 6:28 AM, alexxx.magni at gmail.com wrote:

> Hi there,
> with V.6.0 I keep on with my experiment in translating a large C++
> spin simulation program.
>
> What I'm bouncing my head against today is the following:
>
> there is a way in M to describe objects (matrices) having an arbitrary
> number of dimensions, defined just at runtime?
>
> In detail, I work on an orthogonal lattice where my spins are defined,
> but the simulations require sometimes to deal with 1d (arrays),
> sometimes more.
>
> Yet I'd like to write the most general code it is possible, e.g. when
> writing a procedure that - given a location in the lattice at the
> coordinates {i,j,...} - returns a list of locations of the nearest
> neighbors
> (in 1d: {{i-1},{i+1}}; in 2d: {{i-1,j},{i+1,j},{i,j-1},{i,j+1}} and so
> on...)

How's this?

In[11]:=
neighbors[pnt_]:=
   Table[pnt+Table[d[i],{i,Length[pnt]}],
     Evaluate[Sequence@@Table[{d[i],-1,1,2},{i,Length[pnt]}]]]
neighbors[{i,j}]
Out[12]=
{{{-1+i,-1+j},{-1+i,1+j}},{{1+i,-1+j},{1+i,1+j}}}

You have to specify 1D points as {i} but you could do

neighbors[pnt_List]:=
   Table[pnt+Table[d[i],{i,Length[pnt]}],
     Evaluate[Sequence@@Table[{d[i],-1,1,2},{i,Length[pnt]}]]]
neighbors[pnt_?SymbolQ]:=neighbors[{pnt}]

or

neighbors[pnt_?AtomQ]:=neighbors[{pnt}]

or something like that as suits your needs.

Regards,

Ssezi



  • Prev by Date: Re: Stopping Automatic Animation in v6
  • Next by Date: Re: New in Version 6
  • Previous by thread: matrices with arbitrary dimensionality
  • Next by thread: Re: matrices with arbitrary dimensionality