DragonFly On-Line Manual Pages
MPI_Graph_neighbors_count(3) MPI MPI_Graph_neighbors_count(3)
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)
comm - communicator with graph topology (handle)
rank - rank of process in group of comm (integer)
- number of neighbors of specified process (integer)
THREAD AND INTERRUPT SAFETY
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
NOTES FOR FORTRAN
All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK ) have
an additional argument ierr at the end of the argument list. ierr 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
the call statement.
All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in
All MPI routines (except MPI_Wtime and MPI_Wtick ) 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
communicators), MPI_File_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 not 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 MPI_ANY_SOURCE .