[petsc-users] matrix-free snes with frozen preconditioner

[Matthew Knepley]

On Tue, Sep 26, 2017 at 8:59 AM, Praveen C <cpraveen at gmail.com> wrote:

> Thank you. I had to do this
>
>    ierr = SNESSetLagJacobian(snes,-2); CHKERRQ(ierr);
>    ierr = SNESSetLagPreconditioner(snes,-2); CHKERRQ(ierr);
>
> Now I see that my FormJacobian function is called only once. Is this
> correct way to use it ?
>

Yes

   Matt


> Best
> praveen
>
> On Tue, Sep 26, 2017 at 6:00 PM, Matthew Knepley <knepley at gmail.com>
> wrote:
>
>> On Tue, Sep 26, 2017 at 8:28 AM, Praveen C <cpraveen at gmail.com> wrote:
>>
>>> Dear all
>>>
>>> I am solving a nonlinear problem using matrix-free approach in snes and
>>> I give a preconditioner matrix via SNESSetJacobian. My preconditioner is
>>> based on a first order scheme which is linear and hence preconditioner
>>> matrix will not change. How do I tell snes not to recompute it ?
>>>
>>
>> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/
>> SNES/SNESSetLagPreconditioner.html
>>
>>    Matt
>>
>>
>>> Thanks
>>> praveen
>>>
>>
>>
>>
>> --
>> 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.caam.rice.edu/~mk51/>
>>
>
>


-- 
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.caam.rice.edu/~mk51/>
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