Returns the number of neighbors of a node associated with a graph topology
int MPI_Graph_neighbors_count ( comm, rank, nneighbors )
|comm ||communicator with graph topology (handle)
|rank ||rank of process in group of comm (integer)
- number of neighbors of specified process (integer)
Notes for Fortran
All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK)
havean additional argument ierr at the end of the argument list.
ierris an integer and has the same meaning as the return value of the
routinein C. In Fortran, MPI routines are subroutines, and are invoked with
All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type
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
lastargument. Before the value is returned, the current MPI error handler
iscalled. By default, this error handler aborts the MPI job. The error
handlermay be changed with MPI_Errhandler_set; the predefined error
handlerMPI_ERRORS_RETURN may be used to cause error values to be returned.
Note that MPI does not guarentee that an MPI program can continue
- 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.