Re: [ublas] matrix various matrix multiply timing results

From: Matthias Troyer (troyer_at_[hidden])
Date: 2005-06-08 15:49:33

On Jun 8, 2005, at 10:35 PM, Gunter Winkler wrote:
> Yes, ublas can not (and will not) compete with atlas. You can play  
> with
> different matrix products and matrix sizes with the attached sample
> program.
>
> You see atlas is at least 4 times faster than ublas. For more details,
> please, look at the source.

During the ublas review at boost, it was mentioned that  
competitiveness with BLAS/ATLAS, e.g. by using those libraries was an  
essential goal. With a factor of four in performance, ublas is  
unfortunately *completely useless* for any serious high performance  
work. With CPU time costs (total cost of ownership) for some  
calculations that we perform of the order off several ten thousand US  
$, we cannot afford spending even a factor 4 more.

It is thus a pity that ublas will not make use of atlas, although it  
would be so easy: just use blas for any expression (such as dense  
matrix multiplication) that can be mapped to a blas call.

Best regards

Matthias