From Martin Maechler <maechler@stat.math.ethz.ch>  Fri Jan 22 08:08:50 1999
From: Martin Maechler <maechler@stat.math.ethz.ch> (Martin Maechler)
Date: Fri, 22 Jan 1999 09:08:50 +0100
Subject: backsolve... --> class()es for special matrices ?
In-Reply-To: <Pine.GSO.3.96.990121172536.29339O-100000@laplace> (message from
 Jonathan Rougier on Thu, 21 Jan 1999 17:29:42 +0000 (GMT))
Message-ID: <199901220808.JAA05768@sophie.ethz.ch>


>>>>> "JonR" == Jonathan Rougier <J.C.Rougier@durham.ac.uk> writes:

    JonR> ...  By the way, I have `solve'
    JonR> methods for triangular matrices and variance matrices -- would
    JonR> you be interested?

	{ Jonathan, I hope it's okay if I CC this to R-devel;  
	  this must be of a wider interest }

Ye.e..s;  
for triangular ones, there's the 4 different ways of 
backsolve()/forwardsolve()..

Well, we (R core) have  discussed matrix classes months and years ago..
and haven't really started doing anything about it.

I think we then agreed to follow Splus'  Matrix library
and use class "Matrix"
(and classes inheriting from "Matrix", i.e.
	class == c("specialMatrix", "Matrix")
).

If we really go into this, then 
we'd probably want to use the SAME class names that S-plus' library(Matrix)
is using. 
Also, I remember that people (on the old R-testers list?) 
very much desired to have 1-column or 1-row matrices instead of vectors
when working within the "Matrix" class  [= behavior of  Octave/Matlab ?]

Other opinions / (code) contributions ?

Martin Maechler <maechler@stat.math.ethz.ch>	http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum SOL G1;	Sonneggstr.33
ETH (Federal Inst. Technology)	8092 Zurich	SWITZERLAND
phone: x-41-1-632-3408		fax: ...-1086			<><
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backsolve... --> class()es for special matrices ?
Martin Maechler