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Letian_W_
Beginner
111 Views

How to set the adaqute parameters for feast eigen solver

I'm using feast general Eigen solver to solve the Eigen value equations. However, I found it is difficult to follow a general rules to set the emin, emax and m0. It seems I need to know in advance about the range of Eigenvalues for the m0 mode, if I set a large number to emax which exceeds the eigenvalues of the m0 mode, it will report error message 3. On the other hand, if I set emax too small, the solver will give incorrect predictions of the eigenvalues.

I'm solving a vibration problem and I want to do the following 2 things:

1. Find the lowest m number of eigenvalues, I cannot know in advance and hope the code tell me what is the emax

2. Find all the Eigenvalues between emin and emax, I do not know how many modes between the range and would like the code tells me that.

And ultimately

3. Calculate the first m eigenvalues between emin and emax: if there is more than m modes between emin and emax, I'm only interested in the first m modes. Or, if there is only less than m modes' Eigenvalue falls in the range, I only care those less than m modes.

What is the best way to set up the emin/emax and m0, m? Thanks.

 

LEtian

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2 Replies
111 Views

Hi,

Current version of MKL Extended Eigensolver support only case when user provide interval and number of eigenvalue inside interval that a bit different to what you want. However we investigate possibility to expand current algorithm to find lowest n/ biggest n eigenvalue - could we continue discuss it with you in private thread?

Thanks,

Alex

Letian_W_
Beginner
111 Views

Alex,

 

Thank you for the reply. Yes, I’m interested in private discussion about this.

 

In the vibration field, we often require the lowest n eigenvalues without knowing the eigenvalues range,  or to calculate the eigenvalue range without knowing how many eigenvalues in that range.  Most commercial finite element package (such as ANSYS/NASTRAN) has that feature, it will much help if FEAST has that feature.

 

Letian

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