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From Gilles <gil...@harfang.homelinux.org>
Subject Re: [Math] Re: LU decomposition very SLOW (commons.math3.linear)
Date Sat, 29 Oct 2016 13:46:25 GMT
Hi.

This conversation should preferably be continued on the
"dev" ML.
[CC'ing there.]

Best regards,
Gilles

On Sat, 29 Oct 2016 13:43:43 +0200, Eric Barnhill wrote:
> Hi Wilbur,
>
> That is strange that such a basic technique appears to be at odds 
> with best
> practices, especially when said best practice is out of numerical 
> recipes,
> which has such broad authority.
>
> I think you would be welcome to push the change if you were 
> interested to
> and your contribution would be welcome.
>
> Thank you also for citing the smile library. That appears to be an
> extraordinarily rich Java library. It is a good example of why 
> projects
> need active, interested, expert maintainers; if code is not 
> maintained by
> such a person it is generally quickly surpassed by other code 
> elsewhere.
>
> Best,
> Eric
> Well, I tried the same with "Array2DRowRealMatrix" but it made no 
> difference
> at all.
>
> Meanwhile I cloned the CM snapshot and checked the source code. The 
> authors
> of the "LUDecomposition" class state that their code "is based on the 
> class
> with similar name from the JAMA library" but this seems not the case! 
> The
> Jama implementation is quite different -- actually the same as the 
> alternate
> (Num. Recipes) implementation I had supplied earlier (and also runs 
> at the
> expected speed)!
>
> So, whatever the reason was to abandon the JAMA version, the current 
> Commons
> Math implementation is certainly much inferior in terms of 
> performance.
> Which is astonishing given the popularity of this method.
>
> Will ask the "dev" mailing list, as suggested ...
>
> Thanks,
> Wilhelm
>
>
>
>
>
> --
> View this message in context: http://apache-commons.680414.
> n4.nabble.com/math-LU-decomposition-very-SLOW-commons-math3-linear-
> tp4692255p4692283.html
> Sent from the Commons - User mailing list archive at Nabble.com.
>
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