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.
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.
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?
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.