.. _mpi_dist_graph_neighbors:


MPI_Dist_graph_neighbors
========================

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:ref:`MPI_Dist_graph_neighbors` |mdash| Returns the neighbors of the calling
process in a distributed graph topology.

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.. include:: ./bindings/mpi_dist_graph_neighbors.rst

INPUT PARAMETERS
----------------
* ``comm``: Communicator with distributed graph topology (handle).
* ``maxindegree``: Size of *sources* and *sourceweights* arrays (non-negative integer).
* ``maxoutdegree``: Size of *destinations* and *destweights* arrays (non-negative integer).

OUTPUT PARAMETERS
-----------------
* ``sources``: Processes for which the calling process is a destination (array of non-negative integers).
* ``sourceweights``: Weights of the edges into the calling process (array of non-negative integers).
* ``destinations``: Processes for which the calling process is a source (array of non-negative integers).
* ``destweights``: Weights of the edges out of the calling process (array of non-negative integers).
* ``ierror``: Fortran only: Error status (integer).

DESCRIPTION
-----------

:ref:`MPI_Dist_graph_neighbors` returns the source and destination ranks in a
distributed graph topology for the calling process. This call will
return up to *maxindegree* source ranks in the *sources* array and up to
*maxoutdegree* destination ranks in the *destinations* array. If weights
were specified at the time of the communicator's creation then the
associated weights are returned in the *sourceweights* and *destweights*
arrays. If the communicator was created with
:ref:`MPI_Dist_graph_create_adjacent` then the order of the values in *sources*
and *destinations* is identical to the input that was used by the
process with the same rank in comm_old in the creation call.


ERRORS
------

.. include:: ./ERRORS.rst

.. seealso::
   * :ref:`MPI_Dist_graph_neighbors_count`