MPI_Graph_neighbors_count - Returns the number of neighbors of a node associated
with a graph topology
int MPI_Graph_neighbors_count(MPI_Comm comm, int rank, int *nneighbors)
- - communicator with graph topology (handle)
- - rank of process in group of comm (integer)
- - number of neighbors of specified process (integer)
This routine is both thread- and interrupt-safe. This means that this routine
may safely be used by multiple threads and from within a signal handler.
All MPI routines in Fortran (except for MPI_WTIME
have an additional argument ierr
at the end of the argument list.
is an integer and has the same meaning as the return value of the
routine in C. In Fortran, MPI routines are subroutines, and are invoked with
All MPI objects (e.g., MPI_Datatype
) are of type
All MPI routines (except MPI_Wtime
) return an error
value; C routines as the value of the function and Fortran routines in the
last argument. Before the value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job. The error handler
may be changed with MPI_Comm_set_errhandler
(for files), and MPI_Win_set_errhandler
(for RMA windows). The MPI-1 routine MPI_Errhandler_set
may be used but
its use is deprecated. The predefined error handler MPI_ERRORS_RETURN
may be used to cause error values to be returned. Note that MPI does
guarentee that an MPI program can continue past an error; however,
MPI implementations will attempt to continue whenever possible.
- - No error; MPI routine completed successfully.
- - Invalid topology. Either there is no topology associated with this
communicator, or it is not the correct type (e.g., MPI_CART when
expecting MPI_GRAPH ).
- - Invalid communicator. A common error is to use a null communicator in a
call (not even allowed in MPI_Comm_rank ).
- - Invalid argument. Some argument is invalid and is not identified by a
specific error class (e.g., MPI_ERR_RANK ).
- - Invalid source or destination rank. Ranks must be between zero and the
size of the communicator minus one; ranks in a receive ( MPI_Recv ,
MPI_Irecv , MPI_Sendrecv , etc.) may also be