[petsc-users] Solve for all repeated eigenvalues

[Hong]

Greg:
Find out what default solver, convergence tolerance are used. For
duplicate/clustered eigenvalues, you need strong eigensolver.
Hong

> (by the way this is a standard Hermitian eigenvalue problem)
>
> On Thu, Jun 28, 2018 at 1:53 PM, Greg Meyer <gregory.meyer at gmail.com>
> wrote:
>
>> Hi all,
>>
>> I'm using SLEPc to solve for some eigenvalues. If I ask for the
>> eigenvalues with the leftmost real part (using SMALLEST_REAL), and there
>> are repeated eigenvalues, it appears that the solver does not always find
>> all of the repeated values before jumping up to the next unique eigenvalue.
>> For example if the lowest eigenvalues of my matrix are [-12, -10, -10, -10,
>> -8], and I request 4 eigenvalues, I may get [-12, -10, -10, -8]. I'm using
>> the default solver. Is there any way, or any solver, that ensures that no
>> eigenvalues are skipped?
>>
>> Thanks in advance,
>> Greg
>>
>
>
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