Re: array cross sections

[Mike Miller]

On Tue, 24 Aug 2004, Geraint Paul Bevan wrote:

> Have a look at the 'find' function. You can use it to extract elements 
> which meet some criteria. For example, to get all the elements of a 3x3 
> matrix which are less than 0.5:
>
> octave> a = rand (3,3)
> a =
>
> ~  0.81472  0.83501  0.91338
> ~  0.13548  0.12699  0.22103
> ~  0.90579  0.96887  0.63236
>
> octave> [i,j,v] = find (a .* (a<0.5))


Two questions...

First, isn't this a more efficient way to get 'v'?...

a(find(a<0.5))

...and does that require do_fortran_indexing = 1?


Second question.  How does "find" work with higher-dimensional arrays? 
Does one do this sort of thing with a three-diminsional array?...

[i,j,k,v] = find(a .* (a<0.5))

Best

Mike



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