The Math Forum

Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Math Forum » Discussions » Software » comp.soft-sys.matlab

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: How accurate are eigenvalues/vectors returned by eig and eigs?
Replies: 3   Last Post: Jan 24, 2013 4:53 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Bruno Luong

Posts: 9,822
Registered: 7/26/08
Re: How accurate are eigenvalues/vectors returned by eig and eigs?
Posted: Jan 18, 2013 3:33 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

"Nick" wrote in message <kdbtrd$kfo$>...
> Does EIG or EIGS provide any guarantees as to the accuracy of the eigenvalues / eigenvectors returned?


>This is, how accurate is the numerical estimates of the eigenvalues/eigenvectors (I am especially concerned about the eigenvalues) to the "true" eigenvalues/vectors. I know that it will be quite accurate but I imagine it's also a function of how well conditioned the matrix is.

Conditioning of eigen values calculation is NOT conditioning of the matrix. To make the long story short, it's some what related to the conditioning of V, the output of EIG. This is an intrinsic characteristic of eigen-value problem. On top of that, there is some error related to the algorithm itself. Direct method, such as EIG tends to be good. Iterative methods such as EIGS are notorious to be unstable, the first (corresponds to the largest) eigen vector estimated is usually OK, but things get worse for other vectors.


Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© The Math Forum at NCTM 1994-2018. All Rights Reserved.