I would love to see some tests of pure XQuery implementations of both
sparse and dense operations. I suspect performance of matrix multiply,
inversion, etc, will be poorer than in C++ or Java, but I would expect
performance comparable to Perl or Python (w/o its numpy extension) -
just a wild guess. I'd also expect it might be easier to get good
sparse performance. I don't know why, just a hunch.
But the more interesting question for me is whether language changes are
really needed to support this. I would have thought that proper
optimization of operations on sequences would be enough? So for
example, an extension module using sequences as matrix datatypes could
possibly optimize performance using a lower-level implementation. Does
anyone see any reason why that wouldn't be possible?
-Mike
PS:
I reviewed the discussion you referred to, jean-marc, but it seems to
have more to do with using functions as map keys, and I don't see any
direct connection to linear algebra?
On 12/31/2013 9:55 AM, jean-marc Mercier wrote:
It is not due to the spec. It is rather due to the common usage of
XQUERY, forcing vendor solutions (as BaseX) to focus primarily on XML
Data Base requests more than algorithmic performances.
There are actually some threads that are discussing these performance
issues in the context of maps (maps are for instance used for sparse
matrix representations) : look for instance to ""map module for XQUERY
?" that I initiated or "Higher-order XQuery Modules" by Leo from
BaseX, on [email protected] <http://x-query.com> mailing list.
Anyhow, to write a serious linear algebra modulus, the basic need is
to have a vector containers. Unfortunately, XQUERY does not provide
any performant vector containers at present time, and it is not
possible to code them in pure XQUERY : I have tried, and more
experienced xquery developpers than me have also tried, without success.
We have to wait for the XQUERY version that will give us these
containers, a decision to be taken by the W3C.
2013/12/31 Andrew Welch <[email protected]
<mailto:[email protected]>>
Are you saying the spec as it stands somehow forces all
implementations to be 1000x slower, or just what you have observed
in some particular implementation?
On 31 Dec 2013 14:27, "jean-marc Mercier"
<[email protected] <mailto:[email protected]>>
wrote:
>
> As far as I understand, you want to write a linear algebra
module using XQUERY ?
> If so, I opened a thread some months ago about this idea. My
opinion today is that this is a false good idea at present time.
>
> 1) XQUERY would be really good for writing concise, efficient
linear algebra modulus.
> 2) However, I strongly recommend to wait a little bit for
starting coding : the current version of XQUERY (3.0) suffers from
performance issues. A linear algebra modulus written in XQUERY is
expected to have performances performances 1000 X slower than its
corresponding C++ or JAVA (you can measure it precisely). Any
mathematician linear algebra modulus would probably trashed your
modulus after the first test.
>
> Hope this helps
>
>
>
> 2013/12/31 Ihe Onwuka <[email protected]
<mailto:[email protected]>>
>>
>> Assuming a sparse representation it is about 4 lines of SQL.
This is known not least because you can read enough articles and
papers that discuss it and it optimises well. The obvious google
search does not reveal any corresponding XQuery discussion,
neither does it appear to have surfaced on this or the eXist
mailing list (allowing for my deficient search skills). For
something so "trivial" I thought that was rather strange. Hence I
thought it would be prudent to ask before naively embarking on a
600k X 40k matrix multiplication.
>>
>>
>>
>> On Tue, Dec 31, 2013 at 11:31 AM, Andrew Welch
<[email protected] <mailto:[email protected]>> wrote:
>>>
>>>
>>> It should be pretty trivial...
>>>
>>> On 31 Dec 2013 11:07, "Ihe Onwuka" <[email protected]
<mailto:[email protected]>> wrote:
>>> >
>>> > Has anybody tried this in XQuery or if I am so foolish (not
yet but give me time) would I be the courageous
<culturalReference>http://www.youtube.com/watch?v=ik8JT2S-kBE</culturalReference>
early adopter.
>>> >
>>> >
>>> > _______________________________________________
>>> > [email protected] <mailto:[email protected]>
>>> > http://x-query.com/mailman/listinfo/talk
>>
>>
>>
>> _______________________________________________
>> [email protected] <mailto:[email protected]>
>> http://x-query.com/mailman/listinfo/talk
>
>
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