Re: [boost] Interest in static-sized valarray

From: Paul Baxter (pauljbaxter_at_[hidden])
Date: 2006-01-28 13:45:44

>> I have a complete implementation that models std::valarray in every
>> possible way (with compile-time known limitations) including
>> expression-template support for the numeric ops. My testing indicates
>> a decent performance increase over gcc4's valarray for small number of
>> elements <1000.
>>
>> If anyone has any interest, I'll put together some docs and throw it
>> in
>> the sandbox.
>
> I've no immediate use, but it does sound interesting.

In order to get an idea whether its gcc's valarray implementation at fault, 
you could evaluate macstl (macs and pcs) at www.pixelglow.com

They cite significant speed improvements just by replacing gcc's valarray 
with their alternative (albeit they are concerned with vectorised operations 
almost exclusively).

Its got a slightly restrictive license, but has valarrays and similar fixed 
size alternatives.

A quick benchmark of this might convince you of what is worth pursuing.

FWIW wrapping simple C arrays and using 'restrict' seems to work as well in 
many optimising compilers I've looked at on the PC.

Something like macstl wins when you have longer operations that can make use 
of expression templates.

I'd LOVE to see something like MacSTL developed for Boost. I haven't really 
been following MTL recently, but some smart people are working on it behind 
the scenes. I'm hoping that can be used as a framework for an alternative.

Paul