Re: Problem with pdist

[Jaroslav Hajek]

On Wed, Jul 14, 2010 at 8:09 PM, Esteban Cervetto
<address@hidden> wrote:
> Hello:
>
> I am having problems with the pdist function. It seems not to do enough
> strong to calculate the next problem:
>
>
> octave:22> pdist(X,"mahalanobis")
>
> error: memory exhausted or requested size too large for range of Octave's
> index
>
> type -- trying to return to prompt
>
> octave:22> size(X)
>
> ans =
>
> 2 8993
>
> octave:23>
>
>
>
>
>
> However, Mahalanobis distance is usually used in datamining studies, and a
> sample of 8993 registers and two variables is small.
>
>
>
> It exist a form to improve dramatically the efficiency of octave
> with functions related with data mining or pattern classification?
>
>
>
> Links to similar topics are well received.
>
>
>

It seems the bottleneck here is Octave's nchoosek, which apparently
sucks for nchoosek(1:N, 2) where N is several thousand.
Hmmm. Perhaps something can be done there...

-- 
RNDr. Jaroslav Hajek, PhD
computing expert & GNU Octave developer
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz