[petsc-users] any reasons to distinguish MPIU_SUM from MPI_SUM?

[Fande Kong]

Hi all,

I was wondering why, in Petsc,  MPI_Reduce with PetscInt needs MPI_SUM
meanwhile MPI_Reduce with PetscReal needs MPIU_SUM? Do we have any special
reasons to distinguish them?

Thanks,

Fande Kong,