17.2.179. MPI_Graphdims_get

MPI_Graphdims_get - Retrieves graph topology information associated with a communicator.

17.2.179.1. Syntax

17.2.179.1.1. C Syntax

#include <mpi.h>

int MPI_Graphdims_get(MPI_Comm comm, int *nnodes, int *nedges)

17.2.179.1.2. Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'

MPI_GRAPHDIMS_GET(COMM, NNODES, NEDGES, IERROR)
    INTEGER COMM, NNODES, NEDGES, IERROR

17.2.179.1.3. 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

17.2.179.2. Input Parameter

  • comm : Communicator for group with graph structure (handle).

17.2.179.3. Output Parameters

  • nnodes : Number of nodes in graph (integer).

  • nedges : Number of edges in graph (integer).

  • IERROR : Fortran only: Error status (integer).

17.2.179.4. 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.

17.2.179.5. Errors

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.

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