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Hi, ah, ok that's it, we are using these 3 options: -eps_error_absolute -eps_error_relative -eps_error_backward The first two gives the warning but the last one gives no warning but the values. . . Thanks a lot! :) Eric On 2024-03-07 10: 36, Jose
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<meta charset="UTF-8"></head><body><pre style="font-family: sans-serif; font-size: 100%; white-space: pre-wrap; word-wrap: break-word">Hi,
ah, ok that's it, we are using these 3 options:
-eps_error_absolute
-eps_error_relative
-eps_error_backward
The first two gives the warning but the last one gives no warning but
the values...
Thanks a lot! :)
Eric
On 2024-03-07 10:36, Jose E. Roman wrote:
> You are calling EPSErrorView() somehow. This function checks the residual errors. If you requested EPS_ERROR_RELATIVE then the error for the zero eigenvalues will be large (division by 0).
> Are you calling EPSErrorView() three times? Probably the 3rd message is a call with EPS_ERROR_ABSOLUTE, in which case all errors are below the tolerance.
>
> Jose
>
>
>> El 7 mar 2024, a las 16:29, Eric Chamberland <Eric.Chamberland@giref.ulaval.ca> escribió:
>>
>> Hi,
>> wow, it was only that, it's now working perfectly!
>> Curiously, I still have 2 times the message about relative errors followed by a new one with converged values, see:
>> options_eps_gen Linear eigensolve converged (13 eigenpairs) due to CONVERGED_TOL; iterations 2
>> Problem: some of the first 10 relative errors are higher than the tolerance
>>
>> Problem: some of the first 10 relative errors are higher than the tolerance
>>
>> All requested eigenvalues computed up to the required tolerance:
>> 0.00000, 0.00000, 0.00000, 199.28609, 415.65289, 570.21994, 1294.72406, 1295.67360,
>> 3769.78800, 3771.15894
>>
>>
>> So is it intended to write these 2 warnings?
>> Anyway thanks a lot! :)
>> Eric
>>
>> On 2024-03-07 02:24, Jose E. Roman wrote:
>>> 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 <pierre@joliv.et> escribió:
>>>>
>>>> This Message Is From an External Sender
>>>> This message came from outside your organization.
>>>> 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 <petsc-users@mcs.anl.gov> wrote:
>>>>>
>>>>> This Message Is From an External Sender
>>>>> This message came from outside your organization.
>>>>> 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>
>>>>>
>> --
>> Eric Chamberland, ing., M. Ing
>> Professionnel de recherche
>> GIREF/Université Laval
>> (418) 656-2131 poste 41 22 42
--
Eric Chamberland, ing., M. Ing
Professionnel de recherche
GIREF/Université Laval
(418) 656-2131 poste 41 22 42
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