NAME

       MPI_Graph_neighbors_count  - Returns the number of neighbors of a node associated with a graph topology.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Graph_neighbors_count(MPI_Comm comm, int rank,
            int *nneighbors)

Fortran Syntax

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_GRAPH_NEIGHBORS_COUNT(COMM, RANK, NNEIGHBORS, IERROR)
            INTEGER   COMM, RANK, NNEIGHBORS, IERROR

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Graph_neighbors_count(comm, rank, nneighbors, ierror)
            TYPE(MPI_Comm), INTENT(IN) :: comm
            INTEGER, INTENT(IN) :: rank
            INTEGER, INTENT(OUT) :: nneighbors
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

       #include <mpi.h>
       int Graphcomm::Get_neighbors_count(int rank) const

INPUT PARAMETERS

       comm      Communicator with graph topology (handle).

       rank      Rank of process in group of comm (integer).

OUTPUT PARAMETERS

       nneighbors
                 Number of neighbors of specified process (integer).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_Graph_neighbors_count  and  MPI_Graph_neighbors  provide  adjacency  information for a general, graph
       topology. MPI_Graph_neighbors_count returns the number of neighbors for the process signified by rank.

ERRORS

       Almost all MPI routines return an error value; C routines as  the  value  of  the  function  and  Fortran
       routines in the last argument. C++ functions do not return errors. If the default error handler is set to
       MPI::ERRORS_THROW_EXCEPTIONS,  then  on  error  the  C++  exception  mechanism  will  be used to throw an
       MPI::Exception object.

       Before the error value is returned, the current MPI error handler  is  called.  By  default,  this  error
       handler  aborts  the  MPI  job,  except  for  I/O  function errors. The error handler may be changed with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values
       to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

SEE ALSO

       MPI_Graph_neighbors

4.1.6                                             Sep 30, 2023                      MPI_Graph_neighbors_count(3)