Re: [eigen] calculating on ranges

[Benjamin Schindler <bschindler@xxxxxxxxxxxxxxx>]

On the bottom, there is a link to another version which is supposedly 
even twice as fast... it's homepage has moved, but I located it, may be 
it's interesting:

http://arithmex.com/

Cheers
Benjamin

Benoit Jacob wrote:
> 2009/1/27 Jos van den Oever <jvdoever@xxxxxxxxx>:
>   
> > 2009/1/27 Benoit Jacob <jacob.benoit.1@xxxxxxxxx>:
> >     
> > > Google found code here:
> > > http://gruntthepeon.free.fr/ssemath/
> > > http://gruntthepeon.free.fr/ssemath/sse_mathfun.h
> > >
> > > We could strip a lot of stuff from this file and keep only the SSE2 path.
> > >
> > > That would be stuff for Eigen 2.1.
> > >       
> > I was just about to post that link. A 5-6 fold speedup is no joke!
> >
> > I meant to ask how to go about implementing the cwise().exp().
> > Can I do this via inheritance? Are there any things to mind when
> > implementing this function so that it will be vectorized properly?
> >     
>
> Well cwise().exp() is implemented, the problem is that it's not
> vectorized. This would be implemented by only modifying the
> corresponding functor, ei_scalar_exp_op, defined in
> eigen2/Eigen/src/Array/Functors.h.
>
> For examples of already vectorized functors, look e.g. at
> ei_scalar_sum_op defined in eigen2/Eigen/src/Core/Functors.h.
>
> Basically it is just a matter of implementing the packetOp() method in
> the functor. This method would call a portable wrapper (let's call it
> ei_pexp) around the SIMD stuff. This wrapper would be declared (and
> dummy-implemented for possible non-SIMD usage) in GenericPacketMath.h.
> It would then get specialized for each SIMD platform, e.g. in
> arch/SSE/PacketMath.h.
>
> Just in case you want to play with that ;)
>
> Cheers,
> Benoit
>
> PS. Need to check that the zlib license is OK to relicense to LGPL and
> in any case it's good manners to get in touch with the author "Grunt
> the peon" ;)
>
>
>