[Insight-users] vnl!! ==> QR matrix decomposition.

Luis Ibanez luis.ibanez@kitware.com
Mon, 09 Dec 2002 08:05:55 -0500


Hi digvijay,

Vnl delegates the QR matrix decomposition to a
function taken from linpack. The original fortran
is writen in fortran and can be found in the
directory

    Insight/Code/Numerics/vxl/v3p/netlib

on the file

          cqrdc.f

This file was translated to C using "f2c".


 From the comments in the fortran file:

c     cqrdc uses householder transformations to compute the qr
c     factorization of an n by p matrix x.  column pivoting
c     based on the 2-norms of the reduced columns may be
c     performed at the users option.


Please let us know if you have further questions.


   Thanks


     Luis


=====================================

digvijay singh wrote:

> hi luis and others!!
> could you please give me some info on the vnl_qr
> resolve in vnl.....what methodology does it use  viz
> the householder transformation, givens rotation ,
> gram-schmidt decomposition or some other.....
> thanks
> digvijay
> 
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