MPISTATUSIGNORE

MPI_STATUS_IGNORE is a predefined constant in the MPI (Message Passing Interface) standard. It indicates that the status argument of an MPI function is not required or that no status information should be returned. It is commonly used when a program does not need details about the received message, such as its source, tag, or condition of delivery.

In C and C++, MPI_STATUS_IGNORE is passed in place of a pointer to an MPI_Status for the status parameter of certain routines. For example, a receive operation can be written as MPI_Recv(buffer, count, datatype, source, tag, comm, MPI_STATUS_IGNORE), signaling that the status is not needed. For routines that might return multiple statuses, the corresponding constant MPI_STATUSES_IGNORE can be used to indicate that no statuses are required for any of the requests, such as in MPI_Waitall or MPI_Testall.

MPI_STATUS_IGNORE is defined in mpi.h and is implementation-defined in its exact representation. It should not be inspected or manipulated; it simply instructs the MPI implementation to omit filling a status object. When status information is needed, a real MPI_Status object (or an array of statuses in multi-request calls) should be provided instead.

In Fortran bindings, MPI_STATUS_IGNORE and MPI_STATUSES_IGNORE fulfill the same role, allowing programs to omit status information when it is unnecessary. See also MPI_STATUSES_IGNORE and related routines like MPI_Wait, MPI_Recv, and MPI_Test to understand when using these ignore constants is appropriate.