[petsc-users] portability question for reduce operations

[Jed Brown]

Ed Bueler <elbueler at alaska.edu> writes:
> option 1. full use of MPIU_ types and ops:
>
> PetscReal     x, xloc;
> PetscInt        n, nloc;
> MPI_Allreduce(&xloc,&x,1,MPIU_REAL,MPIU_SUM,comm);
> MPI_Allreduce(&nloc,&n,1,MPIU_INT,MPIU_SUM,comm);

Use MPI_SUM for integer types.  MPIU_SUM is for real/scalar types.
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