Fwd: RE: QRDecomposition

[boisvert@nist.gov]

Sender: "Cleve Moler" <Cleve.Moler@mathworks.com>
Subject: RE: QRDecomposition


Hi --

You are right -- the Linstats toolbox on MATLAB Central does make use of
QR with column pivoting.  As I said earlier, including column pivoting
in our Java code is nontrivial.  You might want to consider calling
MATLAB or LAPACK from Java instead.
  
  -- Cleve

-----Original Message-----
From: jama@nist.gov [mailto:jama@nist.gov] On Behalf Of Sione
Sent: Thursday, July 26, 2007 4:11 PM
To: Multiple recipients of list
Subject: Re: QRDecomposition

Cleve,

There are a few  Matlab functions  from some toolboxes available for 
free download on the internet that I want to port to Java using JAMA,  
which require the use of :

[Q,R,E] = QR(A) ;

One such function is  "solve.m"  which is called by  another function  
"manova.m" where I want to port into Java  from the "Linstats" toolbox ,

and is available from  Matlab Central.

http://www.mathworks.cn/matlabcentral/fileexchange/loadFile.do?objectId=
13493&objectType=file

Cheers,
Sione.


Cleve Moler wrote:
> Hi, Sione --
>
> Including column permutations in the QR decomposition involves major
> modifications to the code.  Why do you think you need it?
>
>  -- Cleve
>
> -----Original Message-----
> From: jama@NIST.GOV [mailto:jama@NIST.GOV] On Behalf Of Sione
> Sent: Wednesday, April 25, 2007 8:09 AM
> To: Multiple recipients of list
> Subject: QRDecomposition
>
> Hi All,
>
> Does anyone know of how to modify the  QRDecomposition  class so   to
be
>
> able to do what  Matlab  "qr"  command does,  such as the following 
> description in Matlab.
>
> [Q,R,E] = QR(A) produces unitary Q, upper triangular R and a
> permutation matrix E so that A*E = Q*R. The column permutation E is
> chosen so that ABS(DIAG(R)) is decreasing.
>
> I want to modify the  QRDecomposition  class so that it also
calculates
>
> "E" , the permutation matrix.
>
> Any help would be appreciated.
>
> Cheers,
> Sione.
>
>
>
>
>
>
>
>
>
>
>






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