oracular (3) MPI_Graph_get.openmpi.3.gz

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