RE: [Vxl-maintainers] LINPACK vs LAPACK

[<Ian...@st...>]

Tom,

Other maintainers may offer a more authoritative answer, but here is a quick one.

VXL uses both linpack and lapack.
  C:\workspace\Lvxl\v3p\netlib>grep -i lapack * | wc
    268    2282   16064
  C:\workspace\Lvxl\v3p\netlib>grep -i linpack * | wc
     98     611    5560

It appears, in particular, that the SVD code does currently use the linpack routine. I can't find
any notes to suggest a reason for preferring linpack over lapack for this use, so it could just be
historical. It would be straight forward to modify vnl_svd.* to use the lapack version instead. 

As to whether it would offer a significant speed improvement, it isn't clear from the LAPACK
documentation that this is the case on normal uniprocessor workstations. It does appear however,
that LAPACK's SVD code is more accurate. I guess someone should do some tests to confirm that the
lapack version really is superior (or at least no worse) when used within vnl.

Ian.

> -----Original Message-----
> From: Tom Wright [mailto:tom...@mi...]
> Sent: Friday, February 21, 2003 11:48 AM
> To: vxl...@li...
> Subject: [Vxl-maintainers] LINPACK vs LAPACK
> 
> 
> Dear Sir/Madam,
> 
> I am interested in using the VXL libraries for a project that I am 
> currently working on, but after looking at the documentation have the 
> following question: why are the underlying numerical routines 
> implemented using the LINPACK library rather than LAPACK library? I 
> would have thought that this would provide a significant speed 
> improvement over your current implementation.
> 
> Thanks very much in advance,
> 
> Tom Wright
> 
> --
> Dr Thomas Wright
> Mirada Solutions Ltd
> Oxford Centre for Innovation
> Mill Street, Oxford, OX2 0JX, UK
> Tel: 44 (0) 1 865 811125
> Fax: 44 (0) 1 865 724 890
> e-mail: Tom...@mi...
> web: www.mirada-solutions.com
> 
> 
> 
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