[petsc-users] Recommended examples for using KSP and multigrid with DM

[TAY wee-beng]

Hi,

I'm using DMDA. The LHS of the poisson eqn is fixed, only the RHS changes.

I thought I can't find ex29.c in the current ver of PETSc, so I thought 
it's no longer valid. Do I always have to get the jacobian as in ex29 to 
solve the Poisson eqn?

What about a good ex. using KSPBCGS to solve my momentum eqn with DMDA?

Thank you.

Yours sincerely,

TAY wee-beng

On 4/11/2015 6:43 AM, Barry Smith wrote:
>    Are you using DMDA or DMPLEX or some other DM? Does the Poisson equation change (variable coefficient) or is it a constant coefficient with the same values for all solves? ex29.c could still possibly serve as a model for the Poisson subproblem, why do you say it is no longer valid?
>
>    Barry
>
>
>> On Apr 8, 2015, at 10:18 PM, TAY wee-beng <zonexo at gmail.com> wrote:
>>
>> Hi,
>>
>> I was following example ex29 in the past to write the code to solve my Poisson eqn using DM. Now it seems that ex29 is no longer valid. Which example should I follow now?
>>
>> Also, I am using KSPBCGS to solve my momentum eqn in the past. Do I need to change much if I'm now using DM? If so, what is a good example?
>>
>> -- 
>> Thank you
>>
>> Yours sincerely,
>>
>> TAY wee-beng
>>