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Subject: Re: [boost] Interest in multi-dimensional array class templates.
From: Brian Smith (bjs3141_at_[hidden])
Date: 2011-06-22 17:31:36

On 6/22/11, Fabio Fracassi <f.fracassi_at_[hidden]> wrote:
> On 21/6/2011 22:28, Brian Smith wrote:
>> The arrays are not specifically designed to deal with image data,
>> although image and graphic libraries could make use of them. It's not
>> clear whether this is the case for GIL having never used it myself.
>> Looking through GIL's tutorial though and ignoring image specific
>> terminology there does appear to be some similarity.
>> The main difference between the math arrays in the library and uBLAS
>> is that they're defined as fixed-size arrays. The other differences at
>> the moment is only dense arrays and operations on them are available,
>> and no algebra has been implemented.
> AFAIK there are fixed size arrays for boost ublas in the most recent
> version(s?), but I am not entirely sure.
> I guess the question I am asking is when should I use your arrays over
> Can your arrays be integrated?
If the array dimensions you'll be using are known at compile time,
which they must be to use the libraries math arrays, then the
comparative tests I've done show better performance of the libraries'
arrays over uBLAS, given the currently implemented operations. Blocked
array expressions of the form matrix< matrix < etc., > > work as
expected and can reduce the number of cache misses compared to a
single matrix< > declaration for relatively large arrays. I've never
used GIL so I really couldn't say when to use the libraries' arrays or
that library.

The storage type of uBLAS arrays, as far as I'm aware, is always a
linear array of consecutive memory locations where the type implements
special purpose iterators, etc. As such I would presume integration is
not possible with that library, however, I've never tried. Whether
integration with GIL is possible is also unknown.

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