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Subject: Re: [boost] Interest in multi-dimensional array class templates.
From: Brian Smith (bjs3141_at_[hidden])
Date: 2011-06-19 06:42:12

On 6/19/11, Joel falcou <joel.falcou_at_[hidden]> wrote:
> On 18/06/11 17:38, Brian Smith wrote:
>> The boilerplate expression templates have already been implemented for
>> scalars, vectors and matrices. The original idea was to include the
>> various matrix types and supply algorithms for the algebra that did
>> not rely on LAPACK since Fortran layout or adaptation of it has not
>> been implemented.
> Not using BLAS/LAPAKC when you can is really shootign your own foot.
> No way you can beat those. The architecture where they are not avialable
> ar nowadays very scarce. As for FORTRAn adaptation, beign able to
> specify a custom storage order should be possible and is usually trivial
> once you get a proper abstraction of data block management whicvh is
> *not* the stupid old T* with polynomial index access.
Nothing was completely ruled out.

>> At some point collaboration would probably have been
>> necessary, either that or integration of a suitable library written in
>> C++.
> Without wanting to derails the thread, we have a large effort going on
> nt2 atm.
Having had a brief look at nt2 my calculations suggest that in the
main it is a result of the 23343rd reinvention of the wheel. Still
worth the effort though.

>> Other commitments however have slowed progress and your
>> observation about the work involved is well received. At the moment
>> I'm not sure of the best way forward for the development of this part
>> of the library. As far as the multi-dimensional arrays are concerned
>> expression templates have not been implemented the rudiments were put
>> in place for anyone to roll their own. In general though that will not
>> be necessary since the intention was for them to be useful as is.
> What i wanted to say is that using proto makes you concentrate on the
> real deal. No need to reivnetn ET for the 23458th times.
The main focus of the library was supposed to be the multi-dimensional
arrays and there really was never any intention to implement
expression templates on top of them, since I've got no idea what an
operator on a multi-dimensional array means to someone who uses them.
While a fair bit of effort went into the matrices etc., and they will
no doubt be useful in some applications, I realise a more significant
effort would be needed in order to compete with nt2 say. We'll call it
a work in progress that at the moment is not making much progress.
While I don't think this renders them ineffectual as far as inclusion
to Boost is concerned if the communities' decision is to remove them
until such times that they outperform nt2 say, then so be it.
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