oracular (3) MPI_Graphdims_get.openmpi.3.gz

NAME

       MPI_Graphdims_get  - Retrieves graph topology information associated with a communicator.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Graphdims_get(MPI_Comm comm, int *nnodes, int *nedges)

Fortran Syntax

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_GRAPHDIMS_GET(COMM, NNODES, NEDGES, IERROR)
            INTEGER   COMM, NNODES, NEDGES, IERROR

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Graphdims_get(comm, nnodes, nedges, ierror)
            TYPE(MPI_Comm), INTENT(IN) :: comm
            INTEGER, INTENT(OUT) :: nnodes, nedges
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

       #include <mpi.h>
       void Graphcomm::Get dims(int nnodes[], int nedges[]) const

INPUT PARAMETER

       comm      Communicator for group with graph structure (handle).

OUTPUT PARAMETERS

       nnodes    Number of nodes in graph (integer).

       nedges    Number of edges in graph (integer).

       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_Graph_get