×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

How to Find Similar Eigenvectors

How to Find Similar Eigenvectors

How to Find Similar Eigenvectors

(OP)
If i run a FE model with slight difference, say i changed the Thickness of couple of components, i will get two sets of Eigenvectors. Is there a way, one can find out whether some of these eigenvectors are similar. As the eigenvectors are normalized and linear, only substracting two eigenvector columns will not be enough. What can one do to find out if the two eigenvector columns are similar.
I am using NASTRAN and will use a DMAP code.  

RE: How to Find Similar Eigenvectors

usual way is a least square fit, look at R^2.

 

Cheers

Greg Locock

SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.

RE: How to Find Similar Eigenvectors

There are different normalisation options in most codes, this may help to show the differences better than the default which is usually scaled to max 1.0 displacement.

If you have a decent post-processor, I always animate mode shapes on the screen and spin them around a bit - it will help to reveal any significant differences in shape.

RE: How to Find Similar Eigenvectors

if for some reason you want a quantitative measure you could find the angle between the two vectors in n-space.
 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources