[petsc-users] Question on output vector in vtk file

[Matthew Knepley]

On Mon, Dec 11, 2023 at 4:32 AM Gong Yujie <yc17470 at connect.um.edu.mo>
wrote:

> Dear PETSc developers,
>
> I have a DMPlex DM with 1 field 1dof. I'd like to output a vector with
> block size equals to 3. It seems that there is no response using command
> line option or using some code about PetscViewer.
>

I am not sure how we can do this. If you only have 1 dof per cell (I
assume), how can we have a blocksize of 3?

  Thanks,

     Matt


> The DM is generated with (note that I'm not using PetscFE for
> discretization, just for allocate dof.)
>
> *PetscCall(DMPlexCreateExodusFromFile(PETSC_COMM_WORLD,"tube.exo",interpolate,&dm));*
>
> *PetscCall(PetscFECreateLagrange(PETSC_COMM_SELF,dim,1,PETSC_TRUE,1,PETSC_DETERMINE,&fe));*
> *PetscCall(PetscObjectSetName((PetscObject)fe,"potential_field"));*
> *PetscCall(DMSetField(dm,0,NULL,(PetscObject)fe));*
> *PetscCall(DMPlexDistribute(dm,0,&sf,&dmParallel));*
>
> The Vector is created using
> *PetscCall(DMCreateGlobalVector(dm,&phi_1));*
> *PetscCall(VecSetLocalToGlobalMapping(phi_1,Itog));*
> *PetscCall(VecGetLocalSize(phi_1,&vec_local_size_test));*
> *PetscCall(VecCreateMPI(PETSC_COMM_WORLD, vec_local_size_test*3,
> PETSC_DETERMINE, &u_grad_psi));*
> *PetscCall(VecSetBlockSize(u_grad_psi, 3));*
> *PetscCall(VecSetLocalToGlobalMapping(u_grad_psi,Itog));*
>
> The output command line option is just --vec_view vtk:test.vtk. The PETSc
> version I'm using is 3.19.5.
>
> Could you please give me some advice?
>
> Best Regards,
> Yujie
>


-- 
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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