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Thread Subject:
Convergence of the first eigenvalue of a system

Subject: Convergence of the first eigenvalue of a system

From: Al Sam

Date: 25 Nov, 2013 19:25:12

Message: 1 of 2

Hi all

I had a code in Matlab, and I used it to obtain the eigenvalues of a cantilever beam with variable number of divisions to see the convergence of the eigenvalues to the analytical values. In an older version (2004 I guess) it was OK and I could see convergence. Recently I ran it on the new 2013b and what I get is noticeable oscilations in the first eigenvalue when I increase the number of beam divisions. I think my code is OK, because I can run it on the old version, but I am not sure what is wrong that the new matlab that cannot solve this problem correcly. By increased I mean 200 to 300 elements, which results in a 200*200 or 300*300 matrix. I can put my code here for those who are intrested. Is there something wrong with the newer eigenvalue solvers of Matlab? I run Matlab 2013b on linux redhat.

Thanks in advance

Subject: Convergence of the first eigenvalue of a system

From: Sargondjani

Date: 26 Nov, 2013 17:17:16

Message: 2 of 2

"Al Sam" wrote in message <l7086o$kf9$1@newscl01ah.mathworks.com>...
> Hi all
>
> I had a code in Matlab, and I used it to obtain the eigenvalues of a cantilever beam with variable number of divisions to see the convergence of the eigenvalues to the analytical values. In an older version (2004 I guess) it was OK and I could see convergence. Recently I ran it on the new 2013b and what I get is noticeable oscilations in the first eigenvalue when I increase the number of beam divisions. I think my code is OK, because I can run it on the old version, but I am not sure what is wrong that the new matlab that cannot solve this problem correcly. By increased I mean 200 to 300 elements, which results in a 200*200 or 300*300 matrix. I can put my code here for those who are intrested. Is there something wrong with the newer eigenvalue solvers of Matlab? I run Matlab 2013b on linux redhat.
>
> Thanks in advance

well i guess nobody can help you without having a clue what you are doing... which matlab procedures you use, etc.

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