The standard says that the null handles are invalid for input unless explicitly permitted. There’s no exemption for a datatype argument where the associated count is zero. Bill William Gropp Director, Parallel Computing Institute Thomas M. Siebel Chair in Computer Science Chief Scientist, NCSA University of Illinois Urbana-Champaign On Jan 12, 2016, at 9:26 PM, Jeff Hammond <[email protected]> wrote:
Is it allowed to communicate messages with (buffer=NULL,count=0,type=MPI_DATATYPE_NULL)?
George thinks MPI_DATATYPE_NULL cannot be used even when count=0, which I think is ridiculous, particularly when one makes the analogy to buffer=NULL.
See http://www.open-mpi.org/community/lists/users/2016/01/28255.php for the thread in question.
There is example code in MPI that uses this behavior. George and I agree that example text is non-normative, but I cannot imagine how this example came to exist without the Forum believing it to be valid.
Jeff
-- Jeff Hammond [email protected] http://jeffhammond.github.io/ _______________________________________________ mpi-forum mailing list [email protected] http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-forum