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Re: A plea for gsvd


From: David Bateman
Subject: Re: A plea for gsvd
Date: Sat, 22 Apr 2006 18:33:07 +0200
User-agent: Mozilla Thunderbird 1.0.6-7.5.20060mdk (X11/20050322)

Pascal Dupuis wrote:

>On Wed, Apr 12, 2006 at 10:47:39PM +0200, David Bateman wrote:
>  
>
>>Given code as a basis I'm of course willing to help out, and give
>>suggestions. Firstly, I think as John says, if we are going to modify
>>the SVD classes it must be done against 2.9. However, I'm not sure if it
>>is better to derive a new GSVD class from SVD or where it is better to
>>treat both svd and gsvd in a single class.
>>
>>    
>>
>
>I suggest a two-steps process:
>1) let make GSVD code work, without messing with SVD
>2) let start thinking about merging or derivating the classes when the
>GSVD is fully operationnal.
>
>The revised code, intended for 2.9, is attached. pat1 and pat2 are the
>Makefile patches.
>
>Best regards
>
>Pascal Dupuis
>
>  
>
Pascal,

There were a couple of very simple bugs in your code that I fixed (size
of arg to dggsvd and number of F77 args incorrect), fixing that the code
now appears to work correctly and not seg-fault. Can you check. Also the
help of the gsvd function needs to be updated as it references svd and
in particular suggests using "svd(hilb(3))" as an example. Could you
update this.

As for the next step, I'm not sure that its better to just include this
class as is or adapt the current SVD class to include gsvd as well.
Frankly, the new class is small and so I'd tend to think that it is
better to keep the code seperate. Also whether this goes into the core
or octave-forge is up to John. Probably, it should go into octave-forge
for now and then transition to octave itself if John so wishes. I've
added a makefile that might form the basis of its inclusion in octave-forge.

A final thing is that dggsvd.f and zggsvd.f should probably be included
in this code and conditionally built if lapack is included in libcruft.

Regards
David



Attachment: gsvd.tar.bz2
Description: BZip2 compressed data


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