We had the discussion on the lunch table about how to compare two communicators in a portable manner. Schemes with Fortran voodoo and memcmp in cases of structure packing and all sorts of other nonsense. Just discovered this function in the MPI standard: int MPI_Comm_compare(MPI_Comm comm1, MPI_Comm comm2, int *result) D'oh! -- Pavan -- Pavan Balaji http://www.mcs.anl.gov/~balaji