- PETSc object (Mat, Vec, IS, SNES etc...)
The object be caste with a (PetscObject). NULL can be used to indicate the barrier should be across MPI_COMM_WORLD
Notes
This routine calls MPI_Barrier with the communicator of the PETSc Object obj
Fortran Usage
You may pass PETSC_NULL_VEC or any other PETSc null object, such as PETSC_NULL_MAT, to indicate the barrier should be
across MPI_COMM_WORLD. You can also pass in any PETSc object, Vec, Mat, etc