NAME

       MPI_Graph_get  - Retrieves graph topology information associated with a communicator.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Graph_get(MPI_Comm comm, int maxindex, int maxedges,
            int index[], int edges[])

Fortran Syntax

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_GRAPH_GET(COMM, MAXINDEX, MAXEDGES, INDEX, EDGES, IERROR)
            INTEGER   COMM, MAXINDEX, MAXEDGES, INDEX(*)
            INTEGER   EDGES(*), IERROR

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Graph_get(comm, maxindex, maxedges, index, edges, ierror)
            TYPE(MPI_Comm), INTENT(IN) :: comm
            INTEGER, INTENT(IN) :: maxindex, maxedges
            INTEGER, INTENT(OUT) :: index(maxindex), edges(maxedges)
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

       #include <mpi.h>
       void Graphcomm::Get_topo(int maxindex, int maxedges,
            int index[], int edges[]) const

INPUT PARAMETERS

       comm      Communicator with graph structure (handle).

       maxindex  Length of vector index in the calling program (integer).

       maxedges  Length of vector edges in the calling program (integer).

OUTPUT PARAMETERS

       index     Array of integers containing the graph structure (for details see the definition
                 of MPI_Graph_create).

       edges     Array of integers containing the graph structure.

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       Functions MPI_Graphdims_get and MPI_Graph_get retrieve the graph-topology information that
       was associated with a communicator by MPI_Graph_create.

       The  information  provided by MPI_Graphdims_get can be used to dimension the vectors index
       and edges correctly for a call to MPI_Graph_get.

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_create
       MPI_Graphdims_get