Re: [ublas] Matrix multiplication performance

Subject: Re: [ublas] Matrix multiplication performance
From: Michael Lehn (michael.lehn_at_[hidden])
Date: 2016-01-19 09:41:27

Sorry for the inconvenience.  I guess sending attachments to the mailing list is prohibited.  I put the
code on a website:

http://apfel.mathematik.uni-ulm.de/~lehn/test_ublas/

On 19 Jan 2016, at 15:14, palik imre <imre_palik_at_[hidden]> wrote:

> Hi Michael,
> 
> I cannot see any attachments  ...
> 
> 
> On Tuesday, 19 January 2016, 11:12, palik imre <imre_palik_at_[hidden]> wrote:
> 
> 
> Is there a public git repo for ublas 2.0?
> 
> 
> On Monday, 18 January 2016, 9:25, Oswin Krause <Oswin.Krause_at_[hidden]> wrote:
> 
> 
> Hi Palik,
> 
> this is a known problem. In your case you should already get better 
> performance when using axpy_prod instead of prod. There are currently 
> moves towards a ublas 2.0 which should make this a non-problem in the 
> future.
> 
> 
> On 2016-01-17 21:23, palik imre wrote:
> > Hi all,
> > 
> > It seems that the matrix multiplication in ublas ends up with the
> > trivial algorithm.  On my machine, even the following function
> > outperforms it for square matrices bigger than 173*173 (by a huge
> > margin for matrices bigger than 190*190), while not performing
> > considerably worse for smaller matrices:
> > 
> > matrix<double>
> > matmul_byrow(const matrix<double> &lhs, const matrix<double> &rhs)
> > {
> >  assert(lhs.size2() == rhs.size1());
> >  matrix<double> rv(lhs.size1(), rhs.size2());
> >  matrix<double> r = trans(rhs);
> >  for (unsigned c = 0; c < rhs.size2(); c++)
> >    {
> >      matrix_column<matrix<double> > out(rv, c);
> >      matrix_row<matrix<double> > in(r, c);
> >      out = prod(lhs, in);
> >    }
> >  return rv;
> > }
> > 
> > 
> > Is there anybody working on improving the matrix multiplication 
> > performance?
> > 
> > If not, then I can try to find some spare cycles ...
> > 
> > Cheers,
> > 
> > Imre Palik
> 
> > _______________________________________________
> > ublas mailing list
> > ublas_at_[hidden]
> > http://lists.boost.org/mailman/listinfo.cgi/ublas
> > Sent to: Oswin.Krause_at_[hidden]
> 
> 
> 
> 
> 
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