It is crucial. MPI also doesn't provide sums for __float128 precision. But MPI does always provide sums for 32 and 64 bit integers so no need for MPIU_SUM for PETSC_INT
> On Aug 17, 2015, at 5:49 PM, Satish Balay <[email protected]> wrote: > > I think some MPI impls didn't provide some of the ops on MPI_COMPLEX > datatype. > > So petsc provides these ops for PetscReal i.e MPIU_SUM, MPIU_MAX, MPIU_MIN > > Satish > > On Mon, 17 Aug 2015, Fande Kong wrote: > >> 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, >> >
