[petsc-users] Fortran Interface NULL object / Casting

[Barry Smith]

   You would use PETSC_NULL_DMLABEL but Matt needs to customize the PETSc Fortran stub for DMAddField() for you to handle accepting the NULL from PETSc.

   Barry





> On Dec 8, 2022, at 1:05 PM, Nicholas Arnold-Medabalimi <narnoldm at umich.edu> wrote:
> 
> Hi Petsc Users
> 
> I am trying to use DMAddField in a Fortran code. I had some questions on casting/passing NULL. I follow how to pass NULL for standard types (INT, CHAR, etc). 
> 
> Is there a method/best practice for passing NULL for Petsc type arguments? (In this case DMAddLabel I'd want to pass NULL to a DMLabel Parameter not an intrinsic type)
> 
> For the 2nd question, In some cases in C we would cast a more specific object to Petsc Object 
> DMAddField(dm, NULL, (PetscObject)fvm); (where fvm is a PetscFVM type)
> Is there a method or practice to do the same in Fortran.
> 
> Thanks
> Nicholas
> 
> -- 
> Nicholas Arnold-Medabalimi
> 
> Ph.D. Candidate
> Computational Aeroscience Lab
> University of Michigan

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