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Ublas : |
Subject: Re: [ublas] question about the atlas and
From: Jesse Perla (jesseperla_at_[hidden])
Date: 2009-03-31 17:06:57
2009/3/31 Kaveh Kohan <kaveh.kohan_at_[hidden]>
> Dear All,
>
> - I am a Linux user (Ubuntu 8.10, 64bit, gcc 4.3.2, 4Gig RAM) and I have
> isntalled boost using repository. It seems that atals is not officially part
> of the boost (pleas correct me if I am wrong)? Could anybody kindly tell how
> I can install it? I know that I should find in the sandbox but I could find
> any instruction or step through.
>
Do you mean the installation of atlas itself or the boost numeric bindings
to atlas? Atlas is something you build separately, then you link things
into your project. The numeric bindings will let you use atlas, blas, etc.
with ublas (or other) matrices. The stable interface for the numeric
bindings is in: https://svn.boost.org/svn/boost/sandbox/numeric_bindings-v1/
I have never used the atlas bindings, but you should check out:
http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?Linear_Algebra_With_UBLAS
Also take a look at:
http://www.guwi17.de/ublas/examples/
and there are some examples at:
http://www.cs.colostate.edu/~nate/tutorial/tutorial.html#tabexs
> - My program involves multiplication of very tall matrix by almost square
> matrix (1000000x 30 by 30 x 30). I have performed this multiplication using
> gsl and it produced the result after 4.1second. Similar operation, using
> ublas took about 37second! Similar operation takes about 0.5second in
> MATLAB. I presume that there is a blunder in my program but I cannot figure
> it out:
>
For performance, here is an older link:
http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?Frequently_Asked_Questions_Using_UBLAS
>From what everyone says, the first thing you do for speed is remove
aliasing.
i.e in your code:
noalias(X) = ublas::prod(A,B) ;