Pierre's diagnostic is right, but the suggested option is wrong: it should be -eps_target Also, I would suggest using a larger value, such as -eps_target 0. 1, otherwise the tolerance 1e-14 might not be attained. Jose > El 7 mar 2024, a las
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Pierre's diagnostic is right, but the suggested option is wrong: it should be -eps_target
Also, I would suggest using a larger value, such as -eps_target 0.1, otherwise the tolerance 1e-14 might not be attained.

Jose


> El 7 mar 2024, a las 8:01, Pierre Jolivet <[email protected]> escribió:
> 
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> It seems your A is rank-deficient.
> If you slightly regularize the GEVP, e.g., -st_target 1.0E-6, you’ll get errors closer to 0.
> 
> Thanks,
> Pierre
> 
>> On 6 Mar 2024, at 8:57 PM, Eric Chamberland via petsc-users <[email protected]> wrote:
>> 
>> This Message Is From an External Sender
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>> Hi,
>> 
>> we have a simple generalized Hermitian problem  (Kirchhoff plate 
>> vibration) for which we are comparing SLEPc results with Matlab results.
>> 
>> SLEPc computes eigenvalues correctly, as Matlab does.
>> 
>> However, the output eigenvectors are not fully converged and we are 
>> trying to understand where we have missed a convergence parameter or 
>> anything else about eigenvectors.
>> 
>> SLEPc warns us at the end of EPSSolve with this message:
>> 
>> ---
>>   Problem: some of the first 10 relative errors are higher than the 
>> tolerance
>> ---
>> 
>> And in fact, when we import the resulting vectors into Matlab, 
>> "A*x-B*Lambda*x" isn't close to 0.
>> 
>> Here are attached the EPS view output as the A and B matrices used.
>> 
>> Any help or insights will be appreciated! :)
>> 
>> Thanks,
>> Eric
>> 
>> <epsview.txt><matrice0_gen.m><matrice1_gen.m>

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