[petsc-users] questions

[Barry Smith]

  I added info to the manual page for DMDASetLocalFunction().

On Nov 11, 2011, at 12:13 PM, Matthew Knepley wrote:

> On Fri, Nov 11, 2011 at 6:06 PM, xiaohl <xiaohl at ices.utexas.edu> wrote:
> 
> Hi
> 
> I am going to use user defined context for this function call
> DMDASetLocalFunction(da,(DMDALocalFunction1) FormFunctionLocal);
> 
> But How can I pass the "ctx" to the function FormFunctionLocal;
> 
> PetscErrorCode FormFunctionLocal(DMDALocalInfo *info, PetscScalar ***u,
>                                 PetscScalar ***f, void * ctx){
> }
> 
> I look at the example
> /petsc-3.2-p2/src/snes/examples/tutorials/ex19.c.html
> 
> I think you intialize the "user" context  by
> DMMGCreate(comm,nlevels,&user,&dmmg);
> for DMMG
> 
> Do you have the similar routine for DMDA?
> 
> If you use SNES, then you can pass it as the last argument to
> 
>   http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-dev/docs/manualpages/SNES/SNESSetFunction.html
> 
> If you use SNESetDM() which sets this automatically, then it will use the one given to
> 
>   http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-dev/docs/manualpages/DM/DMSetApplicationContext.html
> 
> Barry: Where should this be documented?
> 
>     Matt
> 
> Hailong
> 
> On Wed, 2 Nov 2011 15:53:27 -0500, Barry Smith <bsmith at mcs.anl.gov> wrote:
> On Nov 2, 2011, at 3:42 PM, Matthew Knepley wrote:
> 
> On Wed, Nov 2, 2011 at 8:38 PM, xiaohl <xiaohl at ices.utexas.edu> wrote:
> Hi
> 
> I am going to implement cell center difference method for
> u = - K grad p
> div u = f
> where p is the pressure , u is the velocity, f is the source term.
> 
> my goal is to assemble the matrix and test the performance of different linear solvers in parallel.
> 
> my question is how can I read the input file for K where K is n*n tensor.
> 
> MatLoad()
> 
>   Hm, I think you should use a DMDA with n*n size dof and then use
> VecLoad() to load the entries of K.
> 
>   Barry
> 
> 
> second one is that do you have any similar examples?
> 
> Nothing with the mixed-discretization of the Laplacian.
> 
>   Matt
> 
> Hailong
> 
> 
> 
> --
> 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
> 
> 
> 
> 
> -- 
> 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