[Insight-users] speed of svd

[Antti Korvenoja]

Hi!

Matlab uses ATLAS (http://math-atlas . sourceforge . net/) for platform
optimized BLAS. It might matter whether LAPACK uses platform optimized BLAS
or not.

-Antti Korvenoja

Quoting "Miller, James V (Research)" <millerjv at crd . ge . com>:

> Aren't most the Lapack routines in vnl already.  Is it just a matter of
> making the vnl_svd use the Lapack routine instead of the Linpack
> routine?
> 
> 
> 
> -----Original Message-----
> From: William A. Hoffman [mailto:billlist at nycap . rr . com]
> Sent: Thursday, November 20, 2003 11:23 AM
> To: John Biddiscombe; Bing Jian; Insight-Users at itk . org
> Subject: RE: [Insight-users] speed of svd
> 
> 
> There is some talk about moving to Lapack in vxl.  However,
> I expect this will be 6 months or so from now before it makes
> it into ITK.
> 
> -Bill
> 
> 
> At 06:05 AM 11/20/2003, John Biddiscombe wrote:
> >I think you'll find that vxl/vnl code uses linpack rather than Lapack
> >(for svd at least) whereas Matlab probably uses lapack.
> >
> >JB
> >
> >> -----Original Message-----
> >> From: insight-users-admin at itk . org 
> >> [mailto:insight-users-admin at itk . org] On Behalf Of Bing Jian
> >> Sent: 20 November 2003 03:49
> >> To: Insight-Users at itk . org
> >> Subject: [Insight-users] speed of svd
> >> 
> >> 
> >> 
> >> Hi, everyone,
> >> 
> >>     I assumed that C/C++ code would be faster than Matlab.
> >> But to my surprise, I found that svd routine in matlab is 
> >> much faster than the one in vxl. I tried it on a 660*660 
> >> matrix, it took matlab <5 seconds. While in using vnl_svd, it 
> >> took about more than 20 seconds.
> >>    Does someone has an idea about this?
> >> 
> >>    Thanks in advance!
> >> 
> >> -- 
> >> Best wishes,
> >> Bing Jian
> >> bjian at cise . ufl . edu
> >> 
> >> 
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> >> Insight-users at itk . org 
> >> http://www . itk . org/mailman/listinfo/i> nsight-users
> >> 
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-- 
Antti Korvenoja
Biomedicum Helsinki, Radiology
P.O. Box 700, 00029 HUS
Finland

tel: +358-9-47171786    :    mobile: +358-40-7498469