[petsc-users] Convergence rate for spatially varying Helmholtz system

[Matthew Knepley]

On Fri, Oct 1, 2021 at 2:10 AM Ramakrishnan Thirumalaisamy <
rthirumalaisam1857 at sdsu.edu> wrote:

> We fixed the issue. The linear operator in the matrix-free solver was set
> up correctly, whereas the linear operator in the preconditioner was not set
> up correctly (it was lagging in time). After setting the linear operators
> correctly, we see that the diagonal system is solved in 1 iteration. Thank
> you.
>

Cool.

  Thanks,

     Matt


> On Thu, Sep 30, 2021 at 5:49 PM Matthew Knepley <knepley at gmail.com> wrote:
>
>> On Thu, Sep 30, 2021 at 6:58 PM Amneet Bhalla <mail2amneet at gmail.com>
>> wrote:
>>
>>>
>>>
>>>>
>>>>    For a diagonal system with this modest range of values Jacobi should
>>>> converge in a single iteration.
>>>>
>>>
>>> This is what I wanted to confirm (and my expectation also). There could
>>> be a bug in the way we are setting up the linear operators in the
>>> preconditioner and the matrix-free solver. We need to do some debugging.
>>>
>>> (with regard to the diagonal).
>>>
>>> We have printed the matrix and viewed it in Matlab. It is a diagonal
>>> matrix.
>>>
>>
>> Can you send us the matrix? This definitely should converge in 1 iterate
>> now, so something I do not understand is going on.
>> I will take any format you've got :)
>>
>>   Thanks,
>>
>>      Matt
>>
>> --
>> What most experimenters take for granted before they begin their
>> experiments is infinitely more interesting than any results to which their
>> experiments lead.
>> -- Norbert Wiener
>>
>> https://www.cse.buffalo.edu/~knepley/
>> <http://www.cse.buffalo.edu/~knepley/>
>>
>

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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