* Ada implementation of QR decomposition
@ 1997-07-24 0:00 Jan Galkowski
1997-07-25 0:00 ` Mats Weber
1997-08-04 0:00 ` Gautier
0 siblings, 2 replies; 4+ messages in thread
From: Jan Galkowski @ 1997-07-24 0:00 UTC (permalink / raw)
I'm lookin' for a time-saver here: Does anyone have an Ada
implementation (preferably generic, but I doubt I'm going to get
that latitude of choice) for the QR decomposition of a real
matrix?
--
Jan Theodore Galkowski,
developer, statistician,
speaking only for myself,
jan@digicomp.com
jtgalkowski@worldnet.att.net
Member,
the American Statistical Association,
the Union of Concerned Scientists.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Ada implementation of QR decomposition
1997-07-24 0:00 Ada implementation of QR decomposition Jan Galkowski
@ 1997-07-25 0:00 ` Mats Weber
1997-08-04 0:00 ` Gautier
1 sibling, 0 replies; 4+ messages in thread
From: Mats Weber @ 1997-07-25 0:00 UTC (permalink / raw)
I don't know what a QR decomposition is, but I have a generic component that
does this:
-- Decomposes A in a product of two matrices L and U such that L*U = A,
-- where L is a lower triangular matrix with all diagonal
-- coefficients equal to ONE and U is an upper triangular matrix.
-- (L and U are stored in A with zero coefficients omitted)
-- P is the permutation of the rows of A necessary to achieve the
-- decomposition in the case of zero pivots, P_ODD is set to TRUE if P
-- is an odd permutation and PERMUTED is set to FALSE if P is the
-- identity permutation.
It is not 100% suitable for numerical work (I used it for operations in finite
fields) because it doesn't choose the pivot very effectively (it just makes
sure it is non-zero), but that should be easy to change. Just tell me if it
suits your needs and I'll post it.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Ada implementation of QR decomposition
1997-07-24 0:00 Ada implementation of QR decomposition Jan Galkowski
1997-07-25 0:00 ` Mats Weber
@ 1997-08-04 0:00 ` Gautier
1997-08-05 0:00 ` Ken Thomas
1 sibling, 1 reply; 4+ messages in thread
From: Gautier @ 1997-08-04 0:00 UTC (permalink / raw)
> I'm lookin' for a time-saver here: Does anyone have an Ada
> implementation (preferably generic, but I doubt I'm going to get
> that latitude of choice) for the QR decomposition of a real
> matrix?
According to the system you're using, you can interface with the
optimised xGEQRF Lapack routine in Fortran.
--
Gautier
--------
Homepage: http://www.unine.ch/math/Personnel/Assistants/Gautier/Montmollin.html
Software: http://www.unine.ch/math/Personnel/Assistants/Gautier/Gaut_FTP.htm
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Ada implementation of QR decomposition
1997-08-04 0:00 ` Gautier
@ 1997-08-05 0:00 ` Ken Thomas
0 siblings, 0 replies; 4+ messages in thread
From: Ken Thomas @ 1997-08-05 0:00 UTC (permalink / raw)
Gautier wrote:
>
> > I'm lookin' for a time-saver here: Does anyone have an Ada
> > implementation (preferably generic, but I doubt I'm going to get
> > that latitude of choice) for the QR decomposition of a real
> > matrix?
>
> According to the system you're using, you can interface with the
> optimised xGEQRF Lapack routine in Fortran.
>
> --
> Gautier
>
> --------
> Homepage: http://www.unine.ch/math/Personnel/Assistants/Gautier/Montmollin.html
> Software: http://www.unine.ch/math/Personnel/Assistants/Gautier/Gaut_FTP.htm
I have an implementation of the QR algorithm in Ada. It is (my own)
child package of generic_real_arrays from Drexel
http://dflwww.ece.drexel.edu/research/ada
I can supply the source.
--
Dr K.S. Thomas
Department of Electronics and Computer Science
University of Southampton
Highfield
Southampton SO17 1BJ
United Kingdom
Telephone : (+44) 01703 593029
Fax : (+44) 01703 593903
email: kst@ecs.soton.ac.uk
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