From: Philippe Monnier <monnier@...>
Date: 2002-01-23T01:32:09+09:00
Subject: Re: swapping arrays

>
> On Wed, 23 Jan 2002, Philippe Monnier wrote:
> > I've tried to comput a half array of n*(n-1) of reals
> > or arrays of reals
> > @prox = Array.new
> > for i in 1..@bornesup-1
> >    @prox[i]  = Array.new
> >    for j in i+1..@bornesup
> >      @prox[i][j] = ....
> >    end
> > end
> > I improved big swap with n=510 and each @prox[i][j] containing an
> > array with 16 real values.
>
> I guess your matrix takes 55 megs of ram ?
>

I've tried once it was going up to 240 megs then back to 200, but it
stil takes 260 megs incremented until morning with more than 600
megs and a night of swaps but at that time I had arrays of strings inside.
I guess I've made some mistakes. I coded again in computing each lines and
forgetting last lines and it stil use 100 megs, but I need to keep all
the array, so I worry about it.


> There are lots of tricks to save a little RAM here and there, but the
> biggest trick will be to download "narray". when you build your 16-element
> arrays, do NArray.double(16). This will take 3 times less
> RAM. (note: NArray is also multidimensional, so you could do
> NArray.double(510,510,16) once, but it won't make a big difference
> compared to the above change.)
>
> and don't forget to number indices starting from 0, or reserve an extra
> unused index.
>

Thanks,

Philippe
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