--- Robert Dodier wrote:
> > Define what you mean by upper triangular form.
> The result appears to
> > be obtained from performing elementary row
> operations on A, and is a
> > triangular matrix.
> >
> > This issue was discussed at length in bug 1064238
> "triangularize gives
> > wrong results."
> >
>
(http://sourceforge.net/tracker/?group_id=4933&atid=104933&func=detail&aid=1064238)
>
> Does anybody know what the return value of
> triangularize is supposed to be?
> The documentation doesn't say, the code doesn't have
> comments,
> and I can't puzzle it out from looking at the code
> (src/matrix.lisp).
>
> I can think of at least three forms of triangular
> decompositions
> (LU, QR, and Cholesky). If we can't figure out what
> triangularize does,
> I'm inclined to cut it and use specific functions
> if/when they become
> available.
>
> There is an LU decomposition in share/linearalgebra/
> (and none others
> that I can find). I wrote a Cholesky decomposition a
> while back but
> didn't commit it (just laziness on my part). There
> doesn't appear to be
> a QR decomposition.
>
> Maybe Fred can tell us what variety of
> triangularization he's looking for.
>
I was expecting LU decomposition, it would be nice if
triangulaize would have an option to set it output to
which of the 3 you indicated above the user wants.
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