Re: multi-dimensional matrix

[Nathan Weisz]

Hi Weijun,

I just asked the same question a couple of days ago.
http://www.octave.org/octave-lists/archive/help-octave.2003/ 
msg01339.html
Got no answer however. :-(

So when I try this (as I would in Matlab) ...
octave:34> a=rand(2)
> a =
>
>   0.493654  0.072149
>   0.024741  0.886199
>
> octave:35> a(:,:,2)=rand(2)

... I get following error message:
> error: invalid number of indices (3) for indexed assignment
> error: assignment failed, or no method for `matrix = matrix'
> error: evaluating assignment expression near line 35, column 9

So my non-expert guess is: no, a multi-dimensional matrix does not  
work. But Perhaps someone else more experienced could comment on that.

Don't know if it helps you, but I temporarily solved my problem using  
cells instead.

> octave:36> b=cell(1,2); %define size of cell
> octave:37> b{1,1}=rand(2);
> octave:38> b{1,2}=rand(2);
> octave:39> whos
>
> *** local user variables:
>
> prot  type                       rows   cols  name
> ====  ====                       ====   ====  ====
>  rwd  cell                          1      2  b
>
> octave:45> b
> b =
> {
>   [1,1] =
>
>     0.70743  0.84567
>     0.33874  0.35939
>
>   [1,2] =
>
>     0.84809  0.51944
>     0.62300  0.88953
>
> }

Yet operations over e.g. a third dimension (e.g., Matlab: mean(a,3)),  
would be a little bit awkward and would need something like a "for i =  
1:..."-statement. Or am I wrong??

Best,

Nathan



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