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Re: sparse matrix support in MathML

From: David Carlisle <davidc@nag.co.uk>
Date: Thu, 31 May 2007 13:39:59 +0100
Message-Id: <200705311239.l4VCdxh6004460@edinburgh.nag.co.uk>
To: www-math@w3.org

 

>t may need to be changed if the author prefers 
> to display a blank here,

I think there's an implication here that the default rendering for a
sparse matrix markup should be the "full matrix" with the 0's filled in
(as zeros or blanks as something to be specified)? Sometimes that's
wanted but sometimes it isn't, basically depending how sparse is your
matrix. If you have a million by million matrix with 6 non zero entries,
you probably want the display to just show those entries and their
indicies:-)

The alternative is just to display the sparse encodings as a vector of
vectors together with the constructor. Either a general "packed"
constructor as Michael just suggested, or more specific constructors for
diagonal or banded forms, or less sparse forms such as upper triangular
or whatever.

Even if not displayed, one could still ask for a specification of the
value of the "unspecified" entries but I suspect that "zero" (in
whatever field you are working over) would cover the vast majority oif
use cases.

David

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Received on Thursday, 31 May 2007 12:40:25 GMT

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