[Insight-users] matrix logarithm

[Zoltan Seress]

Hi Tom,

I have no time to wait, so the second option is not really an option, but
your code is interesting, I hope it will be useful to me. Actually the
logarithms I want to calculate belong to different affine transformation
matrices, so they are probably not symmetric.
So I will look into your implementation. Thanks!

On Mon, Jun 28, 2010 at 10:56 PM, Tom Vercauteren
<tom.vercauteren at m4x.org>wrote:

> Hi Zoltan,
>
> As far as I know, getting the (generic) matrix logarithm in c++ (as
> opposed to python or matlab) is a pain...
>
> Last time I needed it, I wasn't able to find it. Hence, I made my own
> (vnl based) from a previous version of people at Asclepios lab. You
> will find this implementation in an Insight Journal submission of mine
> (look in vnl_sd_matrix_tools.h):
> http://hdl.handle.net/10380/3060
>
> I am definitely not a linear algebra expert and the code is nothing to
> be proud of. Writing good linear algebra is quite challenging. If you
> wait long enough, it could well be that a decent logm will appear in
> eigen:
>
> http://bytebucket.org/eigen/eigen/issue/38/feature-request-more-matrix-functions-eg-matrix
>
> That being said, if you know that your matrices are diagonalisable
> (e.g. symmetric matrices), the problem becomes of course much simpler.
>
> Anyhow, if the logm implementation in vnl_sd_matrix_tools suits your
> need or if you enhance it, be it just by adding more code coverage,
> let me know.
>
> Hope this helps,
> Tom
>
> On Mon, Jun 28, 2010 at 14:00, Zoltan Seress <seress.zoltan at gmail.com>
> wrote:
> > Hi all,
> > Is there a way to get the logarithm (principal) of a matrix with ITK? I
> > haven't found any, but it doesn't mean that there isn't.
> > Thanks!
> >
> > --
> > Zoli
> >
> > _____________________________________
> > Powered by www.kitware.com
> >
> > Visit other Kitware open-source projects at
> > http://www.kitware.com/opensource/opensource.html
> >
> > Kitware offers ITK Training Courses, for more information visit:
> > http://www.kitware.com/products/protraining.html
> >
> > Please keep messages on-topic and check the ITK FAQ at:
> > http://www.itk.org/Wiki/ITK_FAQ
> >
> > Follow this link to subscribe/unsubscribe:
> > http://www.itk.org/mailman/listinfo/insight-users
> >
> >
>



-- 
Zoli
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.itk.org/pipermail/insight-users/attachments/20100629/cc7f5ecb/attachment.htm>