comp.lang.idl-pvwave archive: archive » singular value decompostion

Home » Public Forums » archive » singular value decompostion

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: singular value decompostion [message #16160 is a reply to message #16035]

Fri, 02 July 1999 00:00

H T Onishi
Messages: 7
Registered: April 1999

Junior Member

> Thanks, that clarifies some points. You were correct, I copied down a .46
> rather than a -.46.
>
> I will run through your exercise to make sure I understand correctly.
>
> Do you have any experience with Principal component analysis and how that
can
> be done with SVD?
>
> Thanks again,
>
> Dave
>

I am not an expert in the SVD algorithm. The note by Fogel should be heeded
and you may want to search the appropriate newsgroup for more info. I
believe that the SVD algorithm implemented in IDL was taken from Numerical
Recipes and there seems to be a lot of controversy over those routines. You
may want to read http://math.jpl.nasa.gov/nr/nr-alt.html for more info. I
know that I had to "tweak" an early version of the SVD routine from
Numerical Recipes to get it to work properly -- problems with underflow.

Regarding Principal Component Analysis, I believe that SVD is the key
algorithm used to extract the PC's. I know that it has been used with some
success to remove background clutter from imagery that contains moving
targets. Again I am not an expert here (in fact not even a novice) but from
what I understand a set of images of the same scene -- possibly
multi-spectral -- is combined into a large matrix. Each image is turned
into a vector and the set of vectors is combined into a large matrix. These
vectors span a vector space and the PCs corresponding to the largest
singular values represent clutter vectors that can then be subtracted from
the original image. I think the PCs are in the V matrix, but there is a 50%
chance that I'm wrong about that. That's about all I know. I'm sure there
are many more applications. I suggest you do a search with AltaVista to see
what you can find! Or you can be more conventional and do a literature
search, which might be more fruitful.

Howard

Report message to a moderator

[Message index]

		singular value decompostion By: Dave Bazell on Thu, 01 July 1999 00:00
		Re: singular value decompostion By: H T Onishi on Fri, 02 July 1999 00:00
		Re: singular value decompostion By: H T Onishi on Fri, 02 July 1999 00:00
		Re: singular value decompostion By: Dave Bazell on Thu, 01 July 1999 00:00
		Re: singular value decompostion By: fogel on Thu, 01 July 1999 00:00

Previous Topic:	Table Widget sizing
Next Topic:	Extra space around widget windows....

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Fri Nov 28 21:37:29 PST 2025

Total time taken to generate the page: 0.64347 seconds