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Re: sparse objects

From: Leonardo B. Lopes <leo@iems.nwu.edu>
Date: Fri, 12 Oct 2001 14:04:16 -0500 (CDT)
To: William Arthur Naylor <bill@scl.csd.uwo.ca>
cc: www-math@w3c.org, www-math@w3.org
Message-ID: <Pine.GSO.4.04.10110121324500.10512-100000@gomory.iems.nwu.edu>
Thanks Bill! It has been of help. I remember this CD from my last ventures
into this realm. It is not exactly what we are looking for, but it is a
great start. I should say our primary focus is on communicating these
objects and using other systems to collaborate in the computation. Would
you expect the MathML-enabled tools to be able to understand an object
designed with the directives you pointed out? 

I suppose if we needed to write a small Mathematica/Maple library to
convert the MathML representation we create to something they understand,
that is an acceptable compromise. It sort of defeats the point of having a
standard in some sense, but as long as we are writing the objects in some 
semblance of MathML, it is better than doing it directly in a Mathematica 
or Maple-specific way. Hopefully after some time our approach and others
might compete and a de facto standard might emerge.

The better solution in my view is to have the ability to communicate (at
least, maybe also present) sparse matrices using MathML directly, or at
least have a "MathML-blessed" way of organizing tuples into sparse
objects. If I wanted to collaborate in making that happen, what steps
would be necessary? Is there enough interest out there? Who should we


On Fri, 12 Oct 2001, William Arthur Naylor wrote:

> On Thu, 11 Oct 2001, Leonardo B. Lopes wrote:
> > Dear Friends,
> > 
> > 	About a year ago I asked around in this list and the OM lists 
> > about sparse matrices and vectors, which are central to my field of
> > research. I also (thanks to generous support from WRI) attended the
> > MathML conference in Urbana. The answer I got was basically that MathML
> > was very strongly focused on K12 and that I shouldn't hold my breath. 
> > 
> > 	Well, it turns out that our community is now sufficiently
> > organized that it looks like our standard communication format is actually
> > going to become reality. Of course we would love to be able to use a
> > MathML structure for representing our sparse objects. We would at least
> > like to convey our structures in a way that MathML-aware applications
> > would understand them.
> > 
> > 	I searched the MathML 2.0 recommendation and found no reference to
> > sparse objects. But apparently there are new features in Mathematica 4.0
> > to deal with sparse objects. So that gives me some more hope. 
> > 
> Hi,
> There is an OpenMath CD, which deals with structured matrices, which to a
> large extent are pretty sparse
> (http://www.openmath.org/cdfiles/html/extra/cd/linalg5.html). It doesn't
> deal with general sparse matrices, though it would not be a big deal to
> create a private one that did, (I would suggest representing them as a
> list of tuples, the coordinates and the values of the non zero entries +
> some dimension and rank (though this is redundant) information for the
> whole matrix). Of course if you want these to be MathML compatible, then
> you use a semantics element or a csymbol element.
> hope this has been of help,
> Bill.
> -- 

Leonardo B. Lopes                                       leo@iems.nwu.edu 
Ph.D. Student                                              (847)491-8470
IEMS - Northwestern University              http://www.iems.nwu.edu/~leo
Received on Friday, 12 October 2001 15:04:55 UTC

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