[petsc-users] Questions abt ex22f

[Jed Brown]

On Sun, Apr 22, 2012 at 16:21, TAY wee-beng <zonexo at gmail.com> wrote:

>
> On 22/4/2012 10:02 PM, Matthew Knepley wrote:
>
> On Sun, Apr 22, 2012 at 3:55 PM, TAY wee-beng <zonexo at gmail.com> wrote:
>
>>  Hi,
>>
>> I changed the vs2008 and linux source code to
>> VecView(x,PETSC_VIEWER_STDOUT_WORLD,ierr) but the results for both outputs
>> are 0 and 0.0416667 (except for one value which is 0.0833333) respectively.
>>
>
>  It looks to me like there is a bug in KSPSetUp(). The DMKSPGetContext()
> is returning a null struct,
> so the RHS is never formed, and the Mat is formed by the default call
> to DMComputeJacobian. What
> is intended here with KSPDM?
>
> Hi，
>
> So is there a way to fix the bug? What can be done to get it working? Is
> this the only fortran example which solve the laplacian equation using
> multigrid ?
>

I'm working on it now, will report back when it's fixed. I normally
recommend src/snes/examples/tutorials/ex5f.F, even for linear problems.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120422/0f3ec1ea/attachment.htm>