[Insight-users] dgeqrf, dorgqr don't work properly

[Karthik Krishnan]

Yes. There have been numerical precision issues with netlib routines
compiled with optimization. I haven't poked around enough to learn why :

http://www.itk.org/mailman/private/insight-developers/2005-August/007028.html

http://www.itk.org/mailman/private/insight-developers/2005-November/007385.html

-karthik

On Wed, 2006-01-25 at 16:54 -0500, Jesse C Cronce wrote:
> All,
> 
> The dgeqrf and the dorgqr that come in the 
> 
> /sw_packages/InsightToolkit-2.2.0/Utilities/vxl/v3p/netlib/
> 
> directory do not return valid results. I found this (initially) by using
> octave to do [Q,R] = qr( J, 0 ) - with the blas / atlas stuff that I
> have built, when I then do Q*R I end up with the original J. When the
> code is linked to the libraries that are in the Insight toolkit and call
> the dorgqr.c code, the value returned from Q*R is the different than J
> by a large amount. Now that I have this working correctly, I'm ok, but
> these functions should probably be disabled until they are fixed so that
> in the future someone doesn't stumble on the same problem.
> 
> Thanks,
> JCC
> 
> 
> 
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